Calculate field coverage rate for any tractor, mower, sprayer, or implement — or find how long a job will take.
*Effective width assumes 5 mph average ground speed with 80% efficiency. Adjust as needed.
The standard formula used by ASABE (American Society of Agricultural and Biological Engineers) is:
APH = (Width × Speed × Efficiency) ÷ 8.25
Where width is in feet, speed is in mph, and 8.25 is a constant that converts the product into acres per hour (derived from 43,560 sq ft per acre ÷ 5,280 ft per mile). The efficiency factor — typically 75–85% for most field work — accounts for time lost to turning at headlands, overlapping passes, stopping to refill or adjust, and terrain variability.
Here are typical APH rates for common farm operations at standard field efficiencies:
Field efficiency is the percentage of theoretical capacity you actually achieve in real-world conditions. Even on a perfect flat field with no obstacles, you lose time turning at the ends of each pass (headland turns). On irregular-shaped fields, you lose more. Typical values:
Knowing your acres per hour is essential for scheduling field work within tight weather windows. If a planting window is 5 days and you need to cover 200 acres, you need at least 5 APH with a single machine running 8-hour days — or you need a second machine. APH also helps you price custom work, estimate fuel costs, and compare the productivity of different equipment configurations.
Most farm planning uses an 8-hour productive day, though experienced operators often plan for 10–12 hours during critical seasons. Simply multiply your APH by the number of productive hours you expect to run to get acres per day. Remember to subtract time for refueling, meals, and maintenance — roughly 1 hour per 10-hour day is a safe buffer.
APH = (Implement width in feet × Ground speed in mph × Field efficiency) ÷ 8.25. This is the ASABE standard formula used by extension services and precision ag software worldwide.
It depends on the mower width and speed. A 15-foot finishing mower at 6 mph with 80% efficiency covers about 8.7 acres per hour. A 5-foot mower at 4 mph covers roughly 1.9 acres per hour. Use the calculator above to get the exact number for your setup.
Use your actual working speed, not your top gear speed. Most tillage, planting, and haying work is done at 4–6 mph. Sprayers can run 10–15 mph. If you're unsure, use the GPS speed display on your tractor or time yourself over a measured distance.
Divide total acres by your APH to get hours. For example, 80 acres ÷ 5 APH = 16 hours, which is two 8-hour days. Use Mode 2 above to do this automatically.
Yes — overlap is built into the field efficiency factor. A 5% overlap on a 20-foot implement means you're only gaining 19 feet of new coverage per pass. For precision work like spraying, GPS boom control can reduce overlap to near zero and meaningfully boost your real-world APH.