Mowing Time Calculator

How it works

A mower cuts a strip as wide as its deck, less the overlap with the previous pass, and moves forward at its ground speed. Width times distance per hour is the area it could cut in an hour if it never stopped: the theoretical field capacity used in farm machinery management. At 1 mph a mower travels 5,280 ft in an hour.

No mower cuts all the time. Turns at the ends of each pass, trimming around trees and beds, and emptying the bag take time. Field efficiency is the share of the theoretical rate actually achieved. Iowa State University's Estimating the Field Capacity of Farm Machines (PM 696) lists median field efficiencies of 78–83% for rotary mower-conditioners; the 80% default here is in that range, but a small lawn with many obstacles can be well below it.

Mowing time is the lawn area divided by the effective rate.

Formula

width per pass (ft)  = (deck width − overlap) (in) ÷ 12
theoretical (sq ft/hr) = width (ft) × speed (mph) × 5,280
effective (sq ft/hr)   = theoretical × field efficiency
time (hours)          = area (sq ft) ÷ effective rate
acres per hour        = width (ft) × speed (mph) × efficiency ÷ 8.25

Example

A 42 in deck with the overlap left inside the efficiency figure cuts a 42 in (3.5 ft) strip. At 4 mph that is 3.5 × 4 × 5,280 = 73,920 sq ft an hour with no turns. At 80% efficiency, which covers overlap as well as turns and stops, it mows 59,136 sq ft (1.358 acres) an hour.

A 10,000 sq ft lawn takes 10,000 ÷ 59,136 = 0.169 hours, about 10.1 minutes.

Assumptions and limitations

• Field efficiency covers overlap between passes, turns, trimming round obstacles, emptying the bag and other stops, as Iowa State PM 696 (revised February 2026) defines it; that is why the overlap defaults to 0. An overlap entered alongside such a figure is counted twice; the overlap input is for an efficiency that covers only turns and stops. The 80% default is illustrative: PM 696 lists 78–83% for farm-scale rotary mower-conditioners, and home lawns with beds and trees are often lower.
• Ground speed is the average cutting speed, not the mower's top speed. The default and the walking range in the help text are typical figures, not manufacturer data.
• The time counts mowing only: not trimming and edging by hand, blowing clippings off paths, or getting the mower out and putting it away.
• The lawn is mowed in one direction in parallel passes; striping patterns, double cutting or slopes that force slower speeds take longer.

Frequently asked questions