What is a fleet size calculator?
A fleet size calculator works out how many vehicles and drivers a delivery or service operation needs for the work it does each day. It starts from the stops you make, how long each one takes and how far apart they are, and fits them into the shifts your drivers work.
This calculator finds how many stops one route can hold, turns your daily stops into routes per day, sizes the fleet for your peak day, adds a spare and maintenance reserve, and works out how many drivers you need once days off and absence are counted. Its second tab compares the result with the fleet you run today and puts a monthly cost on any surplus vehicles.
Why getting fleet size right matters
- Every extra vehicle carries fixed cost. Lease or depreciation, insurance, registration and parking are paid whether the vehicle works or not.
- Too few vehicles cost money too. Missed delivery windows, overtime and last-minute rentals appear on peak days and when vehicles are in the workshop.
- Drivers and vehicles are sized differently. A vehicle can run six days a week, but a driver cannot, so the driver count is higher than the route count.
- Growth plans need a number. Knowing how fleet size moves with daily stops tells you when the next vehicle and the next hire are due.
What data do you need to size a fleet?
| Input | Where to find it | Tip |
|---|---|---|
| Stops per day | Order system, dispatch records, proof-of-delivery data | Use an average working day, and set the busiest regular day as the peak uplift. |
| Service time per stop | Geofence arrival and departure times, or a timed sample | Include parking and paperwork, not only the handover. |
| Drive time between stops | Trip reports, or distance between stops and average speed | Use real urban speeds, which are often far below the speed limit. |
| Depot travel per route | Trip reports for the first and last leg | Count both the trip out and the trip back. |
| Shift, breaks and days off | Rosters, HR policy, labor contracts | Check working-time limits that apply to your drivers before you plan longer shifts. |
| Spare reserve | Workshop records | Base it on how many vehicles are usually off the road on a given day. |
How do you calculate how many vehicles you need?
Stops per route
If you enter distance and speed, drive time between stops = distance ÷ speed × 60. Stops per route is then capped by the maximum stops per route and by payload ÷ load per stop, if you enter them.
Routes, vehicles and drivers
Current fleet against required
Fleet size worked example
A parcel operation makes 120 stops a day. Each stop takes 12 minutes, the drive between stops averages 10 minutes, and the trip from the depot and back adds 60 minutes. Drivers work a 9-hour shift with 60 minutes of breaks, one shift per vehicle, six days a week.
- Time for stops is 9 × 60 − 60 − 60 = 420 minutes. One route fits (420 + 10) ÷ (12 + 10) = 19.5, rounded down to 19 stops, under the limit of 25.
- An average day needs 120 ÷ 19 = 6.3, rounded up to 7 routes of about 17 stops. Each takes about 427 of the 480 working minutes, or 89%.
- With a 20% peak uplift, the busiest day has 144 stops, so 144 ÷ 19 = 7.6, or 8 routes. Eight vehicles in service plus a 10% reserve is 8.8, rounded up to 9 vehicles.
- Each route runs 6 days and each driver works 5, with 8% for leave and absence: 8 × 6 ÷ 5 × 1.08 = 10.4, rounded up to 11 drivers.
- The operation runs 11 vehicles and 12 drivers today. That is 2 vehicles over the 9 needed. At 950 a month per vehicle, the surplus costs 1,900 a month, or 22,800 a year. The extra driver at 1,200 a month brings the total to 3,100 a month.
How to read the results
- Stops per route shows what limits a route. If shift time is the limit, cutting service time or drive time adds stops. If the maximum stops or the payload is the limit, a larger vehicle or a second wave may help more.
- Routes on a peak day set the vehicles in service. If the peak is rare, rentals or an extra shift may cost less than owning the vehicles.
- Route time used close to 100% leaves no slack for traffic, failed deliveries or a late start. Many operations plan with some headroom.
- The sensitivity table shows when the next vehicle and the next driver are needed as stops grow or fall.
Common fleet sizing mistakes
- Leaving out depot travel. The first and last legs can take an hour or more, and they are paid time on every route.
- Counting only handover time. Parking, finding the customer and paperwork often take longer than the handover itself.
- Sizing to the average day. A fleet that fits the average day falls short on the busiest regular day.
- One driver per vehicle. Days off, leave and sickness mean a six-day route needs more than one driver.
- No spare vehicles. Without a reserve, every service visit or breakdown removes a route.
Assumptions and limits
Results are estimates based on the values entered. The calculator assumes stops can be shared evenly across routes, with the same average service time and drive time on every route, and one vehicle type. It does not plan actual routes, delivery windows, territories or traffic by time of day. Drivers are staffed for the peak day; if your peak is rare, overtime or temporary drivers may cover it. Check working-time and rest rules that apply to your drivers, and test any change against several weeks of dispatch data before acting on it.