Acres per Hour Calculator
This acres per hour calculator works out how much ground you actually cover in an hour of mowing, spraying, cultivating, drilling or topping, based on your implement width, ground speed and field efficiency. Enter the working width of the implement in metres, your typical speed in kilometres per hour, and an efficiency figure that allows for turning at the headlands, overlapping passes and refilling, and the calculator returns your real work rate in both acres and hectares per hour. Add the size of the paddock you are about to start and it also tells you how long the job will take, which is handy for quoting contract work, planning a spray window before the wind gets up, or deciding whether you can finish before dark. The theoretical rate at 100 percent efficiency is shown alongside so you can see how much time the turns and stoppages cost you. Contractors, lifestyle block owners and farmers all use the same maths: width times speed gives ground covered, and efficiency scales it back to reality. If you think in feet and miles per hour, convert them first, then read your answer in whichever unit your paddocks are measured in.
Field efficiency allows for headland turns, overlap and refilling; 70 to 90 percent is typical. Estimate only: actual rates vary with paddock shape, obstacles and conditions.
How it works
Working width multiplied by ground speed gives the strip of ground you cover: a width in metres times a speed in kilometres per hour equals thousands of square metres per hour, and dividing by 10 converts that to hectares per hour. Multiplying by field efficiency scales the theoretical rate down to what you achieve once turning, overlap and refilling are counted, and multiplying hectares by 2.4710538 converts to acres. The time for the paddock is simply its area divided by your effective work rate in the same unit.
Worked example
You are topping with a 3 metre mower at 8 km/h and expect 80 percent field efficiency. The theoretical rate is 3 x 8 / 10 = 2.4 hectares per hour, and at 80 percent efficiency the effective rate is 1.92 hectares per hour, which is 1.92 x 2.4710538, or about 4.74 acres per hour. A 20 acre paddock therefore takes 20 / 4.74, which is about 4 hours 13 minutes. At 100 percent efficiency the same outfit would manage about 5.93 acres per hour, so the turns and stoppages are costing you roughly one acre every hour.
Fuel, and why it belongs on this page
Fuel is burnt by the hour but paddocks are measured by the hectare, so the two only meet through your work rate. Fuel a hectare is the hourly burn divided by the hectares covered in that hour, which means a wider or faster outfit uses less fuel a hectare at exactly the same burn rate, and a drop in field efficiency raises the fuel cost of the job without the tractor doing anything differently. Those two figures decide contract rates and machinery choices far more than the litres an hour on their own ever do, which is why the running cost sits here beside the work rate rather than on a page of its own. On the same 3 metre mower at 8 km/h and 80 percent efficiency, burning 14 litres an hour at $1.85 a litre, the job costs 7.3 litres a hectare, or $13.49 a hectare, and the 20 acre paddock takes 59 litres and $109.18 of diesel. If the petrol equivalent is being burnt off road in a pump or a generator rather than in a tractor on a road, the excise duty on it may be refundable.
Related calculators
- Off-Road Fuel Excise Refund: claiming duty back on off-road petrol.
- Acreage Calculator: land area in acres and hectares.
- Acres to Hectares Converter: quick unit conversion.
- Fuel Consumption Calculator: fuel used for the job.
- Speed Calculator: speed, distance and time.
- Hours Calculator: add up working hours.