Haul truck fleet sizing calculator
How many trucks does a shift need to move its tonnes? Enter the target, the truck payload, the cycle time at the face and the availability and utilisation your fleet actually achieves. The calculator returns the trucks required, the productive hours behind the figure and the spare capacity the rounding leaves.
You sized the fleet on paper. Mirage measures it every shift.
Raw GPS turned into trips, loading, queuing, idle time and haul truck cycle times, compared with the dispatch plan per shift. Send us a shift of data and we send back a plan, no commitment.
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How to use it
- Enter the tonnes the shift must deliver to the crusher or the dump, and the shift length in hours.
- Enter the rated payload of the truck class and, if the material is light or the loader under-fills, the fill factor.
- Break the cycle into its legs: spot and queue at the loader, loading (passes × pass time), haul loaded, dump, return empty. Use measured times from the fleet management system when you have them.
- Enter the mechanical availability and the utilisation of available time your fleet records, not nameplate figures.
- Read the trucks required and the capacity the rounding leaves. Change one factor at a time to see what moves the count.
The formula and each factor
cycle time = spot + load + haul + dump + return
productive hours = shift hours × availability × utilisation
trips per truck = productive hours × 60 / cycle time
tonnes per truck = trips × payload × fill factor
trucks required = ceiling(target / tonnes per truck)
- Payload
- The rated capacity of the truck class in tonnes. The density of the material and the body size can keep the real load below it: that is what the fill factor corrects.
- Cycle time
- The minutes between two loads for one truck. Haul and return depend on distance, grade and rolling resistance; loading on the loader's passes; spot and queue on how well the fleet is matched to the loader.
- Availability
- Mechanical availability: the share of scheduled hours the truck can work. Downtime for planned maintenance and breakdowns takes the rest.
- Utilisation
- The share of available hours the truck is actually hauling. Shift change, blasting clearances, refuelling, meals and waiting at the loader are the usual losses.
- Ceiling
- Trucks come whole. Rounding 5.4 up to 6 trucks leaves spare capacity; the calculator shows how much, and what cycle would let the fleet drop one truck.
Reference: SAIMM, The determination of haulage-truck requirements for an open-pit operation
A worked example
A quarry must move 12,000 t per 12-hour shift with 90 t trucks. Cycle: 0.5 min spot, 3 min loading, 9 min haul, 1 min dump, 6.5 min return, so 20 minutes. Availability 85%, utilisation 80%: 12 × 0.85 × 0.80 = 8.16 productive hours, so 24.48 trips and 2,203 t per truck and shift. 12,000 / 2,203 = 5.45, so 6 trucks, with 13,219 t of capacity and 10% in hand. At 100% of both factors the same target would take 4 trucks: the two extra trucks are the price of availability and utilisation.
What the estimate leaves out
- It sizes trucks against a target, not against the loader: a fleet larger than the loader can serve queues at the face. Check the match factor (truck cycle ÷ loading time per truck) separately.
- It uses one average cycle. Several faces or dumps at different distances need one calculation per circuit, or a weighted cycle.
- Payload is in tonnes; if you plan in loose cubic metres, convert with the loose density of the material.
FAQ
How do you calculate the number of haul trucks needed?
Divide the tonnes the shift must move by what one truck delivers in that shift: its trips (productive hours × 60 / cycle time) times its payload. Productive hours are the shift hours multiplied by availability and utilisation. Round the result up to whole trucks.
What is the difference between availability and utilisation?
Availability is mechanical: the share of scheduled time the truck is not down for maintenance or breakdown. Utilisation is operational: the share of available time the truck is actually hauling, after shift change, blasting, refuelling and waiting. Multiplied together they give the productive share of the shift.
What is a typical haul truck cycle time?
There is no typical value: it depends on haul distance, grade, rolling resistance, loader size and the traffic on the ramp. Measure it from the fleet management system or with a stopwatch at the face over a full shift, and use the average with its spread, not a single good cycle.
What is the match factor?
The ratio of loader capacity to truck capacity over time: the number of trucks × loading time per truck ÷ truck cycle time. Near 1, loader and trucks are balanced; above 1, trucks queue at the loader; below 1, the loader waits. This calculator sizes the fleet against the production target; check the match factor against the loader next.
Can this be used for quarries and construction earthworks?
Yes: the formula is the same for any load-haul-dump cycle, whether the trucks are rigid haulers in a pit, articulated trucks on an earthworks site or road trucks at a quarry. What changes is the cycle time and the realistic availability and utilisation.
The factors in this formula are read off records, not guessed.
Mirage deploys AI agents that reconcile fuel, haulage and equipment records across sites, so availability, utilisation and tonnes per cycle come from what the fleet actually did, for your planners to use.
See AI for mining operations