How to use the lawn mowing time calculator
- Enter the lawn area in square feet. An acre is 43,560 square feet.
- Enter the cutting width of the mower in inches and your average speed in miles per hour.
- Set the overlap between passes and any extra time for turns and trimming. Both start at zero and you can change them.
- Read the mowing time, the effective cutting width and the area you cover per hour.
Formula
Effective width (ft) = cutting width in inches / 12 x (1 - overlap %)
Area per hour = effective width in ft x speed in mph x 5,280
Time = area / area per hour x 60 minutes x (1 + extra time %)
One mile is 5,280 feet, so a speed in miles per hour becomes feet per hour. The result is an estimate based on a steady speed.
10,000 square feet with a 21 inch deck at 3 mph
A 21 inch deck is 1.75 feet wide. At 3 mph the mower moves 15,840 feet an hour, so it covers 1.75 x 15,840 = 27,720 square feet per hour. The lawn takes 10,000 / 27,720 x 60 = 21.6 minutes.
With 10% overlap the effective width falls to 18.9 inches and the coverage to 24,948 square feet per hour, so the same lawn takes 24.1 minutes. With 20% extra time for turns and trimming and no overlap, the original 21.6 minutes becomes 26 minutes.
Overlap and turns
Overlap is how much each pass re-cuts the last one. Zero overlap assumes perfectly straight, perfectly spaced passes, which is rare in practice. Entering 10 means each pass adds a strip 90% as wide as the deck. Extra time covers corners, obstacles and trimming. Both are your estimates, which is why they are inputs.
Walking pace is a poor guide to mower speed, so use a speed you have measured, for example by timing a known distance. The pace calculator turns a distance and time into a speed.
Planning lawn jobs
Once you know how long a mow takes, you can plan a weekly routine or price a mowing job. To size a seeding or feeding job for the same lawn, see the grass seed calculator, the lawn fertilizer calculator and the sod calculator.
If you water on a schedule, the sprinkler run time calculator turns a target depth into minutes per zone.
Assumptions and limits
- Speed is steady across the whole lawn.
- The area is the mowable grass, with beds and buildings already taken out.
- Overlap and extra time are your estimates and start at zero.
- Slopes, wet grass, bagging and stopping are not modeled.
Frequently asked questions
How long does it take to mow 10,000 square feet?
With a 21 inch deck at 3 mph and no overlap, about 21.6 minutes. Overlap, turns and slopes add time.
How do I calculate mowing time?
Divide the lawn area by the area you cover per hour, which is the effective cutting width in feet times your speed in feet per hour. Multiply by 60 for minutes.
What speed should I enter?
Use your own average speed while cutting. Timing a known distance, such as 100 feet, gives a reliable figure for your mower.
Does a wider deck always save time?
It saves time in open ground because each pass covers more. Tight spaces and many obstacles reduce the gain, so use the extra time box to reflect that.