Implement Field Capacity Calculator
Calculate how many acres or hectares a rotavator, cultivator or plough covers per hour from its width and operating speed.
Enter your details
Enter the working width of your implement and the speed you drive at, and see how many acres or hectares per hour it really covers after turning and overlaps – and how long your field will take.
About the Implement Field Capacity Calculator
Field capacity is the rate at which a machine covers ground. It matters when you hire a tractor by the hour, plan how many days sowing will take, or compare a wider implement with a faster one.
There are two figures:
- Theoretical capacity – width × speed, as if the tractor never turned, stopped or overlapped.
- Effective capacity – what you actually get once headland turns, overlaps, filling seed boxes and short breaks are included. It is the theoretical figure multiplied by field efficiency.
Small and irregular fields have more turns per acre, so their efficiency is lower. Long rectangular fields give the best efficiency.
Typical values
| Implement | Speed (km/h) | Field efficiency |
|---|---|---|
| Rotavator | 2–4 | 70–85% |
| Cultivator (9–11 tyne) | 4–6 | 70–85% |
| Disc harrow | 4–6 | 75–85% |
| M.B. / disc plough | 3–5 | 70–80% |
| Seed drill | 4–6 | 60–75% |
How to use the Implement Field Capacity Calculator
- 1 Enter the working width of the implement.
- 2 Enter your usual driving speed in the field.
- 3 Keep field efficiency at 80%, or lower it for small fields.
- 4 Enter your field area and press Calculate.
The formula we use
Theoretical capacity (ha/h) = Width (m) × Speed (km/h) ÷ 10
Effective capacity = Theoretical capacity × Field efficiency
Acres per hour = Hectares per hour × 2.471Worked example
A 1.8 m rotavator at 3 km/h with 80% field efficiency on a 5-acre field.
- Theoretical = 1.8 × 3 ÷ 10 = 0.54 ha/h.
- Effective = 0.54 × 0.8 = 0.432 ha/h = 1.07 acres per hour.
- 5 acres takes about 4.7 hours (about 56 minutes per acre).
Things to keep in mind
- Measure speed simply: time how long the tractor takes to cover 50 m. Speed (km/h) = 180 ÷ seconds.
- Hourly hire. When you hire by the hour, effective capacity tells you what an acre will really cost.
- Don't overspeed. Rotavating or sowing too fast gives poor tilth or uneven seed depth.
Frequently asked questions
How many acres can a rotavator cover in an hour?
A 1.8 m (6 ft) rotavator usually covers about 0.8–1.2 acres per hour, depending on speed, soil and field shape.
What is field efficiency?
It is the share of time the implement is actually working at full width. Turning at the ends, overlaps and stops reduce it, usually to 70–85%.
How do I find my tractor's speed in the field?
Mark 50 m and time the tractor in its working gear. Speed in km/h is 180 divided by the seconds taken.
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