What size robot mower do I need? Lawn size and slope calculator

• Max lawn size: the model's stated value must be at least what you need (a stated range counts at its low end). Leave it at 0 to skip this check.
• Max slope: the model's stated value must be at least what you need (a stated range counts at its low end). Leave it at 0 to skip this check.
• No boundary wire: when ticked, only models the maker says have it match.
• Multiple zones: when ticked, only models the maker says have it match.

A model that does not state a value we check never counts as a match. Specs come from the makers' pages; each model page links to them. Data checked up to November 9, 2026. Matches are sorted cheapest first.

Measure the lawn, not the lot

A robot mower only needs to cover the grass. Take your lot size and subtract the house, the driveway, patios and flower beds; the lawn is often half the lot or less. Free map tools can measure an area if you trace the lawn's edges. An acre is 43,560 square feet, so a quarter acre is about 10,900 square feet.

The size a maker states is the most the mower can handle in a week under good conditions. Long, narrow strips, many obstacles and fast spring growth all slow it down, so pick a mower rated for comfortably more than your lawn.

Measure the slope

Slope here is in percent: the rise divided by the run, times 100. Lay a straight board on the steepest part of the lawn, level it, and measure how far the low end is above the ground. A 1 foot rise over 4 feet is 25%. Percent is not the same as degrees: 100% is 45°. Rated slopes are measured on dry grass, so wet or uneven hills leave less margin. Our guide to robot mowers on slopes goes further.

Wire or no wire

Older designs follow a boundary wire buried or pegged around the edge of the lawn. Newer mowers use satellite positioning, cameras or laser scanners instead, and you draw the boundary in an app. Tick "No boundary wire" to see only those. Read robot mowers without a boundary wire for how each kind finds its way.

Several lawns

If you have a front and a back lawn with a path or driveway between them, tick "Several separate lawns" to see mowers whose makers say they can mow more than one zone.