# How many acres per hour?

Computes the acres per hour (effective field capacity) of a tractor, mower, sprayer or planter from its working width, ground speed and field efficiency, with hectares per hour and the hours a field takes.

- Page: https://www.acalculator.org/construction/acres-per-hour-calculator
- JSON spec: https://www.acalculator.org/construction/acres-per-hour-calculator.json
- Version: 41ecc3e89012

## Default answer

Example with the default inputs (Working width 20 ft, Ground speed 5 mph, Field efficiency 80%): You can cover about 9.7 acres per hour.

## Inputs

| Key | Label | Description |
| --- | --- | --- |
| w | Working width | The width the implement covers in one pass, without overlap (a 60-inch mower deck is 5 ft). |
| v | Ground speed | The working speed in the field. |
| e | Field efficiency | The share of time spent working at full width, after turns, overlap, filling and stops. |
| field | Field size | The area to cover, to work out the hours. Leave empty to skip. |

## Outputs

| Key | Label | Description |
| --- | --- | --- |
| acres | Field capacity (acres per hour) | Speed × width × field efficiency ÷ 43,560 sq ft. |
| hectares | Field capacity (hectares per hour) | The same capacity in hectares per hour. |
| theoretical | Theoretical capacity (acres per hour) | Speed × width ÷ 43,560 sq ft, at 100% field efficiency. |
| hours | Hours for the field | The field size ÷ the field capacity. |

## Method

Acres per hour = speed × width × field efficiency ÷ 43,560 sq ft; in US units, mph × ft × efficiency ÷ 8.25. Hours = field size ÷ acres per hour.

## Assumptions

- The width is the effective width, without overlap; the speed is the working speed in the field.
- Field efficiency covers time lost to turns, overlap, filling, emptying and small repairs; Iowa State’s example uses 83%.
- 1 acre = 43,560 sq ft and 1 mile = 5,280 ft, so mph × ft ÷ 8.25 gives acres per hour.

## Worked examples

1. w = 9.144, v = 2.2352, e = 83% gives acres = 15.090909, theoretical = 18.181818. Source: Iowa State University Extension, Ag Decision Maker A3-24, Estimating the Field Capacity of Farm Machines (field capacity in acres per hour = speed in mph × width in feet × field efficiency ÷ 8.25, where 8.25 = 43,560 ÷ 5,280; a 30-foot implement at 5.0 mph and 83% field efficiency covers about 15 acres per hour), https://www.extension.iastate.edu/AGDM/crops/html/a3-24.html (retrieved 2026-10-03).
2. w = 6.096, v = 2.68224, e = 80%, field = 647,497.027584 gives acres = 11.636364, hours = 13.75. Source: Iowa State University Extension, Ag Decision Maker A3-24, Estimating the Field Capacity of Farm Machines (field capacity in acres per hour = speed in mph × width in feet × field efficiency ÷ 8.25, where 8.25 = 43,560 ÷ 5,280; a 30-foot implement at 5.0 mph and 83% field efficiency covers about 15 acres per hour), https://www.extension.iastate.edu/AGDM/crops/html/a3-24.html (retrieved 2026-10-03).
3. w = 6, v = 2.777778, e = 75% gives hectares = 4.5, acres = 11.119742. Source: Iowa State University Extension, Ag Decision Maker A3-24, Estimating the Field Capacity of Farm Machines (field capacity in acres per hour = speed in mph × width in feet × field efficiency ÷ 8.25, where 8.25 = 43,560 ÷ 5,280; a 30-foot implement at 5.0 mph and 83% field efficiency covers about 15 acres per hour), https://www.extension.iastate.edu/AGDM/crops/html/a3-24.html (retrieved 2026-10-03).

## FAQ

### How do I calculate acres per hour?

Multiply the speed in miles per hour by the working width in feet and the field efficiency, then divide by 8.25. A 30-foot implement at 5 mph and 83% covers 30 × 5 × 0.83 ÷ 8.25 = 15.1 acres per hour.

### Where does 8.25 come from?

An acre is 43,560 sq ft and a mile is 5,280 ft. A 1-foot strip one mile long is 5,280 sq ft, and 43,560 ÷ 5,280 = 8.25. So mph × feet ÷ 8.25 is acres per hour.

### What is field efficiency?

The share of time the machine works at its full width. Turning at the ends, overlapping passes, filling seed or spray tanks, emptying and small repairs all take time. Iowa State’s example uses 83%; your own records give the best number.

### What width should I use?

The effective width that is new ground on each pass, without overlap. A 60-inch mower deck that overlaps the last pass by 4 inches covers 56 inches, not 60.

### How long will my field take?

Type the field size. The hours are the field size ÷ the acres per hour: 160 acres at 11.64 acres per hour take 13.75 hours.

### Can I use metric units?

Yes. Pick metres and km/h, and the result heads with hectares per hour. A 6 m sprayer at 10 km/h and 75% covers 4.5 ha per hour.

## Sources

- Iowa State University Extension, Ag Decision Maker A3-24, Estimating the Field Capacity of Farm Machines (Hanna; Rosentrater, updated February 2026): field capacity = speed × width × field efficiency ÷ 8.25, with 8.25 = 43,560 ÷ 5,280; a 30-foot implement at 5.0 mph and 83% field efficiency covers about 15 acres per hour. https://www.extension.iastate.edu/AGDM/crops/html/a3-24.html (retrieved 2026-10-03)