Lawn Mowing Time Calculator

This calculator estimates how long it takes to mow a lawn. Enter the lawn area, the cutting width of the mower deck, your mowing speed, how much each pass overlaps the last, and a field efficiency for turns and stops; you get the mowing time and the area covered per hour.

Formula

Effective width (ft) = deck width (in) ÷ 12 × (1 − overlap ÷ 100). Area per hour (ft²/h) = effective width × speed (mph) × 5,280 × efficiency ÷ 100. Mowing time (minutes) = lawn area ÷ area per hour × 60. One acre is 43,560 ft².

• a: lawn area in square feet
• deck: cutting width in inches
• v: mowing speed in miles per hour (walking behind a mower is often 2-3 mph)
• ov: overlap of each pass on the previous one, in percent
• eff: share of the time actually spent cutting, after turns, emptying the bag and stops

Worked Example

A 10,000 ft² lawn, a 42 in deck, 3.5 mph, 10% overlap and 80% efficiency.

1. Effective width = 42 ÷ 12 × 0.90 = 3.15 ft
2. Area per hour = 3.15 × 3.5 × 5,280 × 0.80 = 46,570 ft²/h (1.07 acres/h)
3. Time = 10,000 ÷ 46,569.6 × 60 = 12.88 minutes, shown as 12:53

How to use the result

Use the time to plan a mowing day or to compare decks: going from a 21 in push mower to a 42 in rider halves the passes at the same speed. Raise the efficiency for open, rectangular lawns and lower it for lawns with many trees, beds and tight turns.

Limits and common mistakes

• The estimate covers cutting only. Trimming, edging and blowing clippings take extra time.
• Tall or wet grass forces a slower speed; change the speed rather than the efficiency.
• Speed is ground speed, not the mower’s top speed in transport.

Frequently Asked Questions

How long does it take to mow an acre?

With a 42 in deck at 3.5 mph, 10% overlap and 80% efficiency, about 56 minutes (43,560 ÷ 46,570 × 60 = 56.1).

What efficiency should I use?

About 70-85% for a typical home lawn; open rectangles reach 90%, lawns with many obstacles may be 60%.

Why does overlap matter?

Each pass overlaps the last to avoid stripes of uncut grass, so the mower advances less than its full width.

Can I enter the area in acres?

Multiply acres by 43,560 to get square feet first.

in a | Lawn area | ft² | 10000 | 0
in deck | Mower deck width | in | 42 | 1 | 200
in v | Mowing speed | mph | 3.5 | 0.1 | 20
in ov | Overlap between passes | % | 10 | 0 | 90
in eff | Field efficiency (turns, stops) | % | 80 | 1 | 100
out mins | Mowing time | h:mm:ss | a / (deck / 12 * (1 - ov / 100) * v * 5280 * eff / 100) * 60 | time
out rate | Area mowed per hour | ft²/h | deck / 12 * (1 - ov / 100) * v * 5280 * eff / 100 | 0
out ac | Area mowed per hour | acres/h | rate / 43560 | 2