Mowing Time Estimator

We take your property area and divide it by an effective acres-per-hour rate, then add a trim/cleanup uplift for the work that is not straight mowing.

effectiveAcPerHr = width(in) × speed(mph) × (1 − overlap) ÷ K
mowMinutes       = area(acres) ÷ effectiveAcPerHr × 60
trimMinutes      = mowMinutes × trim
totalMinutes     = mowMinutes × (1 + trim)        ← headline

The divisor K is a fixed, openly-published constant. The 99 constant comes from the unit math itself: a deck w inches wide at s mph covers (w / 12) × (s × 5280) ft²/hr, and an acre is 43,560 ft², which reduces to w × s / 99. The 124 constant is just 99 ÷ 0.80 — Exmark's recommended 80% field-efficiency factor folded in, because the honest number "is more representative of actual mowing conditions as it allows for turns and overlapping." In realistic mode the overlap and the 0.80 factor both apply, so the realistic figure is deliberately slower than the theoretical one.

The constants assume inches and mph. If you enter a metric deck width or a property area in square feet or m², we convert to inches and acres first and leave the constant untouched — we never rescale 99 or 124 to "match" a unit.

Throughput mode reports the effective acres/hour and an acres/day capacity (effectiveAcPerHr × workday hours); trim is a note there, not folded into raw capacity.

The trim/cleanup % is our own conservative default (≈15%), not a cited industry constant — treat it as an operator estimate and adjust it to your property. This tool outputs time only; for a dollar figure use the Lawn Care Pricing calculator, and to sequence a full day use the Route Day Planner.

Formula: effective ac/hr = width(in) × speed(mph) × (1 − overlap) ÷ K · K = 99 (theoretical) or 124 (~80% realistic)

See Sources below ↓