Quantity takeoff in construction: how to do one from PDF drawings
A quantity takeoff is the list of quantities measured from the drawings that an estimate will price: counts, lengths, areas, volumes and weights, each in its unit, with the sheet it came from and the rule used to measure it. To do one from PDF drawings, register the sheets and their revisions, calibrate every view on a written dimension and check it on the other axis, then measure item by item in the unit the bill or price schedule uses. Deduct openings only as the measurement rules say, and write every line on a takeoff sheet someone else can check. The rules are not universal: NRM2 governs UK building bills, a US unit-price contract carries its own measurement clauses, a French contract its own documents. Waste is an allowance you choose, kept outside the measured quantity. The worked example goes from a 1:100 plan to 112.14 m² of blockwork.
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- Jules Toussaint
The general method for building and civil quantities measured from 2D drawings. Measurement standards are paraphrased from their publishers' texts; the contract you price says which one applies.
Who wrote this, and why. Mirage Metrics builds AI agents that measure quantities from construction drawings. At OCBM, a Moroccan general contractor, three agents are in production and 100% of quantities are traceable to the drawing they were measured on; the estimators review the takeoff line by line. At John Cockerill, piping takeoff takes 80 to 90% less time. The method below is the one those agents follow and the one a reviewer checks them against. The service itself is on the takeoff and estimating page.
What a takeoff measures, and the four kinds of quantity
A takeoff answers how much; the estimate that follows answers how much it costs. In UK traditional procurement the quantity surveyor's measurement becomes a bill of quantities that every bidder prices, under RICS's NRM2 (see the NRM2 bill of quantities guide). On a US lump-sum bid each bidder's estimator measures the quantities the price rests on, and the takeoff feeds an estimate organized by CSI MasterFormat division. In French public works, the avant-métré measured from the drawings is distinct from the métré of the work done that payment rests on. Whatever the market, every line comes down to one of five kinds of quantity.
| Kind | Unit (US) | What you need from the drawings | Typical items | Where it goes wrong |
|---|---|---|---|---|
| Count | nr (each) | The symbol, its legend and every sheet it appears on | Doors, fixtures, piles, valves | A symbol hidden under another; one item counted on the plan and again on an enlarged view |
| Length | m (LF) | One dimension along the element | Skirting, kerbs, pipe, cable tray | Walls measured on a face instead of the centre line; vertical drops forgotten |
| Area | m² (SF, SY) | Two dimensions: the plan, plus a section or elevation for heights | Walls, floors, ceilings, roofing, formwork | A height read off a typical note instead of the section; openings deducted against the rules |
| Volume | m³ (CY) | Three dimensions; for earthworks, cross sections | Concrete, excavation, fill | A typical slab thickness applied to thickenings; bulking added to a measured volume |
| Weight | t (US ton of 2,000 lb) | A length or a count, and a unit mass from a schedule | Reinforcement, structural steel | A unit mass taken from the wrong section table |
Source: Units: NRM 2, 3.2.1 (metric units, tonnes to two decimals); WSDOT M 41-10, 1-09.1 ("Ton": 2,000 pounds).
Some items are neither: an item or a lump sum (a temporary works design, a test) is listed, not measured. A material takeoff for piping goes one level further and lists every fitting and bolt set by specification; that method has its own piping takeoff guide, and electrical counts and runs have the electrical takeoff guide.
Scale: calibrate every view, then check it on the other axis
Start with a register before measuring anything: each sheet's number, title, revision, the views it holds and the scale each view states. A sheet often carries a plan at 1:100, an enlargement at 1:50 and details at 1:20, and a calibration is valid only for the view it was made on.
Vector or scanned
A PDF exported from CAD is vector: dimension text can be selected, and a takeoff tool snaps to line ends. A scan is pixels: nothing snaps, and the image may be stretched differently across and down the sheet. Try selecting the text of a dimension; if it highlights, that part of the sheet is vector. A scanned background under vector markups looks vector and measures like a scan.
Calibrate on a written dimension
Bluebeam's own guidance is to use a preset scale only when the scale is known and no scaling happened when the PDF was created, and otherwise to calibrate on a known length: pick its two ends, type the length. It also accepts a separate Y scale, which is what a scan stretched unevenly needs (Bluebeam). Calibrate on the longest written dimension of the view, then measure a second written dimension on the other axis. Compare the two against a tolerance you set; the takeoff sheet has a column for it and recommends none.
- The written dimension wins. A drawing represents; the dimension states. One dimension that disagrees with its scaled length is a drawing error to write up; every dimension off by the same factor means the calibration is wrong.
- Reduced prints change the scale. A3 is half of A1 in both directions, so a 1:50 plan printed on A3 reads 1:100. A half-size US set does the same: 1/4" = 1'-0" is 1:48 and becomes 1/8" = 1'-0", 1:96. An engineering scale of 1" = 20' is 1:240.
- Not to scale means not measured. A view marked NTS, or a single-line schematic, carries no lengths: take the written dimensions, or log an assumption and a question.
Measurement rules: NRM2, US practice and French contracts side by side
The quantity depends on a rule before it depends on the drawing: whether a small opening comes off a wall, whether waste is added, how a curved wall is measured. Those rules come from the method the contract names. The three below are published in full and free to read, and they disagree on almost every row.
| Question | NRM2, UK building work | WSDOT M 41-10, US public works | French public works contracts |
|---|---|---|---|
| What is measured | Work net as fixed in position, unless stated otherwise (3.2.1) | Areas from the neat dimensions in the Plans or as altered by the Engineer; structures on the neat lines (1-09.1) | What the contract documents say: unit prices pay the quantities executed, a lump sum is due whatever the quantities (R2112-6) |
| Waste, laps, joints | Nothing extra is measured: the net quantity is deemed to cover laps, joints and waste, and each item's price includes waste (3.2.1, 3.2.2) | Not measured: material wasted or disposed of contrary to the Contract (1-09.1) | Not set by the general conditions; the technical specification or the price schedule says |
| Small openings and voids | A minimum per work section: masonry under 0.50 m² kept (14); finishes up to 1 m² (28); formwork up to 5 m² (11); concrete voids under 0.05 m³ (11). Voids at the boundary always deducted (3.2.1) | Square-foot and square-yard items: an exception larger than 9 sq ft is subtracted (1-09.1) | No general rule; each regulatory floor area carries its own deductions (R111-22), and none binds a works contract |
| Walls and curved work | On the centre line of the material (3.2.1); masonry walls on the centre line whatever the construction (14) | Linear foot: along the element unless the Plans require otherwise (1-09.1) | Set by the contract documents |
| Rounding | Dimensions to the nearest 10 mm; quantities to whole units, under one given as one; tonnes to two decimals (3.2.1) | To the proper significant figure or fraction of units for each item (1-09.1) | Not set by the general conditions |
| Earthworks | Bulk before excavating, or the net void to be filled; no allowance for bulking or working space (5, note 3) | Average end area, or terrain models; photogrammetric data allowed (1-09.1) | Measured on site and recorded jointly: measurements, gauging, weighing, counts (CCAG 11.2) |
| When quantities move | A provisional quantity is remeasured; a 20% or larger variance opens the rate to review (3.2.7) | Work outside the lines shown or set by the Engineer is not measured (1-09.1) | A lump sum does not move with quantities or with errors in its breakdown (CCAG 10.3.1); a unit-price quantity up by more than a third or down by more than a quarter can earn compensation (16.2) |
Source: NRM 2, 2nd edition, section numbers in brackets, work sections as numbers. WSDOT Standard Specifications M 41-10 (2027), 1-09.1. France: Code de la commande publique R2112-6, CCAG Travaux 2021, arts 10.3.1, 11.2, 16.2, Code de l'urbanisme R111-22.
WSDOT is one state's specification, chosen because it is published whole; other state DOTs and federal agencies write their own measurement and payment sections, and the one in your contract governs. On US building work priced as a lump sum, the bidder's takeoff carries the quantities and its conventions are the estimator's to state at the top of the sheet. The American Society of Professional Estimators publishes Standard Estimating Practice (12th edition, 2025), built on CSI MasterFormat (ASPE).
UK civil engineering bills follow a different standard from NRM2: CESMM4 Revised, published by the Institution of Civil Engineers in June 2019, with work classes A to Z and usable under NEC, FIDIC and ICC contracts (Designing Buildings). Read the class that covers your work before measuring it.
Deductions and waste: two decisions kept apart
Deduct on its own line
Measure the whole element, then deduct each opening on a negative line of its own, never by shortening a dimension. A checker then sees what came off, how big it was and which rule allowed it. Under NRM2, voids under the work section's minimum stay in, and an opening at the edge of the measured area always comes off, whatever its size: a door that cuts the bottom of a wall is deducted even where a small vent in the middle of the same wall is not (NRM 2, 3.2.1 and work section 14). The opening you deduct usually brings items of its own, such as a lintel, reveals and a sill, measured separately.
Waste is a choice, not a number to look up
The measured quantity is what will be built. Offcuts, laps, breakage and over-ordering are an allowance on top of it, for buying, not for the bill: NRM2 measures work net and puts waste in the rate (3.2.1, 3.2.2), and WSDOT does not measure wasted material (1-09.1). No published figure fits every material, crew and room shape, so this page gives none. Set the allowance per material from what your own jobs delivered against what they measured, or from the manufacturer's coverage per unit, and keep it in a column of its own: in the takeoff sheet below it sits in the summary, empty, and never touches the measured quantity.
The takeoff sheet: timesing, dimensions, squaring
Traditional dimension paper has four columns: timesing (how many identical items), the dimensions, the squared result, and the description. A spreadsheet keeps the same logic on one line per measurement: timesing, length, width, height or depth, and a quantity that multiplies what is entered. A count takes timesing only, a length one dimension, an area two, a volume three. Four identical windows are one line timesed by four, not four lines.
Each line also carries what makes it checkable: an item code, the sheet and its revision, the unit, add or deduct, an assumption where the drawing was silent, and a second measure by another method with its status. Round once, at the end, in the summary, as the contract's method says; rounding every line compounds.
Four sheets with working formulas: a scale check per view against your tolerance, the takeoff lines with timesing, dimensions, deductions, sheet and revision, a check measure and its status, and a summary by item code and unit with NRM2 rounding and a waste allowance column you fill. Every dimension and quantity starts empty.
Worked example: a blockwork wall from a 1:100 plan
Illustrative example, invented figures: a single-storey building measured under NRM2
Sheet A-101 revision C, plan at 1:100: a building 12.30 by 8.30 m outside, 300 mm blockwork walls, 3.00 m from slab to wall head on section A-A, one door D1 of 1.00 by 2.10 m, four windows of 1.20 by 1.20 m, two vents of 0.60 by 0.60 m.
Scale. Calibrated on the 12.30 m overall dimension, the 8.30 m one measures 8.27 m: 0.36% short. Every length this wall needs is written on the drawing, so the written values are used and the scaled ones only confirm the calibration.
Centre line. NRM2 measures walls on the centre line (work section 14). Take half a wall off each end of each side: 12.30 less 0.30 is 12.00 m, 8.30 less 0.30 is 8.00 m, so the girth is 2 × (12.00 + 8.00) = 40.00 m. Measuring the outside, 41.20 m, would count each corner twice: 4 × 0.30 = 1.20 m too much.
Gross, then deductions. 40.00 × 3.00 = 120.00 m². D1 is 2.10 m² and sits on the wall's boundary; the four windows are 4 × 1.44 = 5.76 m², each over 0.50 m². Both come off: 7.86 m². Each vent is 0.36 m², under the masonry minimum, so the two stay in the quantity.
| Line | Description | Timesing | Length | Height | m² | Note |
|---|---|---|---|---|---|---|
| 1 | Wall, 300 mm blockwork, centre line | 1 | 40.00 | 3.00 | 120.00 | Height from section A-A |
| 2 | Deduct D1 | 1 | 1.00 | 2.10 | −2.10 | At the wall's boundary |
| 3 | Deduct W1 to W4 | 4 | 1.20 | 1.20 | −5.76 | Each over 0.50 m² |
| V1, V2, 0.60 × 0.60 | 2 | none | Not deducted: under 0.50 m², NRM2 14 | |||
| Net | 112.14 | Billed as 112 m² (3.2.1) |
Net and check. 120.00 − 7.86 = 112.14 m², billed as 112 m² (3.2.1). The independent check uses the mean perimeter: inside, 2 × (11.70 + 7.70) = 38.80 m; the mean of 41.20 and 38.80 is 40.00 m, the same girth. A contract that deducted every opening would give 111.42 m²: the 0.72 m² between the two answers is the rule, not the drawing.
How to check a takeoff before it is priced
A takeoff is checked by someone who did not do it, against the drawings, with a different method where one exists. Before the quantities go to pricing:
- Every sheet in the register is referenced by at least one line, or marked as having nothing to measure.
- Every view used has a scale check line, within the tolerance you set.
- The largest lines have a second measure by another method: a mean perimeter, an area by subtraction, a count against the door or fixture schedule.
- Units match the bill or price schedule line by line: m² against m², not m² against m.
- Each deduction follows the stated rule and sits on its own line; none is hidden in a dimension.
- Rounding is applied once, in the summary, as the contract's method says.
- Every open assumption has become a written question before the tender's deadline for questions.
- The revision on each line is the one being priced.
Then compare a few totals with your own past projects of the same type, per square metre of floor: a wall area or a concrete volume far from what similar buildings gave is a line to reopen, not proof of an error.
When the drawings are revised
A new revision changes quantities that its clouds do not always mark. Compare the sheets, not the clouds: overlay the two revisions, list what moved, and re-measure only the lines whose sheet changed, which is why every line carries its sheet and revision. Keep the old line with its quantity set to zero and a note, rather than overwriting it, so the change is visible: what changed, by how much, and on which sheet. The drawing revision comparison guide covers the comparison itself; whether a change is design development or a client change is a contract question, not a measurement one.
What takeoff software can do, and what stays with the estimator
Software is good at the measuring and at keeping the trail; the rules and the judgement stay with a person. Mirage's agents read PDF and DWG plan sets and extract counts, lengths, areas and volumes. At OCBM they are adapted to the contractor's own drawings and conventions, every quantity carries its source drawing, and the estimators keep control of the final output (OCBM case study).
| Task | Software | The estimator |
|---|---|---|
| Set a scale and measure lengths, areas and counts on screen | On-screen takeoff tools, once a scale is set; Bluebeam calibrates on a known length and takes a separate Y scale | Chooses the dimension to calibrate on and checks it on the other axis |
| Find symbols, trace walls and rooms | AI takeoff tools aim to; test them on your own sheets, vector and scanned | Confirms the legend and the symbol that means two things |
| Apply deduction and rounding rules | Applies the rule it is given, on every line | Decides which method the contract names, and the exceptions |
| Read heights, thicknesses and scope from sections, details and specifications | Agents read them where they are written | Settles drawings that contradict each other or the specification |
| Compare two revisions of a sheet | Lists the quantities that changed | Decides whether a change is design development or a client change |
| Link each quantity to its sheet and revision | Stamps it on every line: 100% of quantities at OCBM | Signs off the takeoff |
The article on AI quantity takeoff describes how automated takeoff reads a plan set.
When this method is not the right one
A 2D drawing takeoff is the wrong starting point in five cases:
- A coordinated model exists. Quantities from a BIM model come from its objects, not from a scale. The measurement rules still apply, but the check becomes whether the model is complete and modelled to those rules.
- The client gives you the quantities. With an NRM2 bill or a French unit-price schedule, you price quantities someone else measured. Check the lines your price depends on: a provisional quantity is remeasured (NRM 2, 3.2.7), and a French lump sum does not move when its quantities were wrong (CCAG Travaux, 10.3.1).
- You are measuring work already built. Payment under a unit-price contract rests on quantities measured on site under the contract's clauses: WSDOT's Engineer measures acceptably completed items (1-09.1), a French contract records measurements jointly (CCAG 11.2). Drawings only set the lines.
- The trade has its own conventions. Cable runs and home runs, piping isometrics and spools: see the electrical and piping guides linked above.
- The drawings are diagrams. A single-line schematic gives connections, not lengths; a quantity taken from it is an assumption to state, not a measurement.
Questions readers ask
A quantity takeoff is the list of quantities measured from the drawings that an estimate will price: counts of items, lengths, areas, volumes and weights, each in its unit, with the sheet and revision it came from and the rule used to measure it. It answers how much; the estimate then answers how much it costs. In UK practice the measurement often becomes a bill of quantities under NRM2 that every bidder prices; in US practice the estimator usually measures for their own bid.
The takeoff measures, the estimate prices. A takeoff says 112.14 m² of 300 mm blockwork measured from sheet A-101 revision C; the estimate adds the rate, which includes labour, materials, plant and waste, then preliminaries, overheads and profit. Keeping them apart lets a reviewer check a quantity against a drawing without reading a price, and reprice a job without remeasuring it.
Only as the measurement rules of the contract say. NRM2 sets a minimum per work section: in masonry, voids under 0.50 m² are not deducted; in floor, wall and ceiling finishes, voids up to 1 m² are not; openings at the boundary of the measured area are always deducted. A WSDOT unit-price contract subtracts an exception larger than 9 square feet from square-foot items. French contracts have no general rule: the specification decides. Record each deduction as its own negative line.
No. The measured quantity is what will be built. Waste, offcuts, laps and breakage are an allowance on top of it, for buying: NRM2 measures work net and puts waste in the rate, and WSDOT does not measure wasted material. The allowance is a decision taken per material, from your own delivered against measured quantities or the manufacturer's coverage, and kept in its own column.
Software measures: once a scale is set, on-screen tools measure lengths, areas and counts, and AI agents read plan sets and extract quantities. What stays with a person is deciding which measurement rules apply, settling drawings that contradict each other, and signing off the takeoff. At OCBM, Mirage's agents are in production and every quantity carries the drawing it was measured on, with the estimators reviewing line by line.
Sources and scope
Checked on . All sources read on 29 October 2026. NRM2 and WSDOT are quoted from the publishers' PDFs; CESMM4 Revised is named from a secondary source and no rule of it is stated.
- RICS, NRM 2: Detailed measurement for building works, 2nd edition (PDF): 3.2.1 net as fixed, net quantity deemed to cover laps, joints and waste, centre line, nearest 10 mm, whole units, tonnes to two decimals, voids at boundaries; 3.2.2 what each item includes; 3.2.7 provisional quantities and the 20% variance; work section 5 note 3 (excavation bulk); 11 (concrete voids under 0.05 m³, formwork voids up to 5 m²); 14 (walls on the centre line, voids under 0.50 m²); 28 (finishes, voids up to 1 m²)
- Washington State DOT, Standard Specifications for Road, Bridge, and Municipal Construction M 41-10 (2027), Division 1 (PDF): 1-09.1 Measurement of Quantities: neat dimensions, exceptions over 9 square feet, linear foot along the element, average end area and terrain models, structures on the neat lines, ton of 2,000 pounds, significant figures, no measurement of wasted material or work outside the lines
- American Society of Professional Estimators, 12th Edition Standard Estimating Practice (web page): 2025 edition in four volumes, built on CSI MasterFormat
- Designing Buildings Wiki, CESMM4 (secondary source): CESMM4 Revised published by ICE in June 2019, classes A to Z, usable with NEC, FIDIC and ICC contracts
- Bluebeam Technical Support, Set the page scale on your drawing: preset scale only when no scaling occurred during PDF creation, calibration on a known length, a separate Y scale, scale applied to one page or a range
- Code de la commande publique, article R2112-6 (France): unit prices applied to quantities actually delivered or executed, lump sums whatever the quantities
- Arrêté du 30 mars 2021, CCAG Travaux (France), JORF of 1 April 2021: 10.3.1 lump sum not changed by quantity differences or errors in its breakdown; 11.2 contradictory records of measurements, gauging, weighing and counts; 16.2 unit-price quantities up by more than a third or down by more than a quarter
- Code de l'urbanisme, article R111-22 (France): surface de plancher and its eight deductions
- Mirage Metrics, OCBM case study: three agents in production, 100% of quantities traceable to a source drawing, estimators reviewing line by line
- Mirage Metrics, John Cockerill case study: 80 to 90% less time spent on piping takeoff
This guide explains a measurement method for educational purposes. The worked example is invented. The measurement rules that bind a takeoff are those of the contract being priced.
Related on this site
- NRM2 bill of quantities: the UK bill a building takeoff becomes
- Electrical takeoff from 2D drawings: counts, runs and the two-level review
- Piping takeoff from isometrics: from ISOs to an MTO and a spool BOM
- Comparing drawing revisions: what a new revision changes in the quantities
- Construction estimate template: where the quantities are priced
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