Truck fleet size calculator

It works out how many trucks you need to haul a quantity of freight over a period, with allowance for maintenance and contingencies, and what it costs per day, per ton and per ton-mile. It compares up to 4 truck types and looks for the cheapest mixed fleet. Use it to plan harvest hauling, construction, raw material supply or shipping, and to check carrier quotes.

The example hauls 13,200 tons of crushed limestone a month over 22 days: 600 tons a day, 20 miles away. The end-dump semitrailer carries 25 tons per trip (weight governs), completes the cycle in 1.92 h and fits 5 trips into a 10-hour day. That is 24 trips a day, 5 trucks running and 7 in the fleet with 90% availability and a 10% reserve, at $6,148 a day or $10.25 per ton.

They carry 15 tons instead of 25, so they need 40 trips and 10 trucks instead of 24 trips and 7 trucks. Each costs a little less per mile and per day, but not enough: $12.93 per ton against $10.25. In this example no mix of types beats the end dumps alone; the calculator only suggests a mixed fleet when it saves more than 2%.

Payload is the legal gross weight for the axle configuration (federal 80,000 lb and the Bridge Formula, plus state rules) minus the truck’s tare weight, from your scale tickets or spec sheet. Body volume in cubic yards is on the body maker’s plate. Cost per mile and per day come from your own books or the trucking cost calculator; list values are only typical.

It is how much of the rated (struck) volume the load actually takes. Struck loads sit near 100%; heaped loads can exceed it, depending on the material, its angle of repose and the tarp. In the example, crushed limestone at 87.5 lb/ft³ would fill 24 yd³ with about 28 tons, more than the 25-ton payload, so weight governs, not volume.

Because each truck makes a whole number of trips a day. In the example, at 20 miles an end dump makes 5 trips; at twice the distance it makes 3 and the fleet goes from 7 to 10 trucks. Saving a few minutes of queue or scale time sometimes changes nothing and sometimes takes a whole truck off, when it gives back one trip a day.

It assumes an empty return, steady demand and the same loading, unloading and queue times for every type. It does not check axle weights, driver hours of service (49 CFR Part 395), time-of-day restrictions or the capacity of loading points, which can create queues. The mixed fleet is a good arrangement under the model, not necessarily the optimum; validate with real cycle data before contracts or investments.