Stepping Stone Calculator

Stones = round up (path length ÷ centre-to-centre spacing) + 1. Each spacing interval needs a stone, and the +1 places the final stone at the very end of the path. For a 5m path at 0.6m spacing that is ceil(5 ÷ 0.6) + 1 = 9 + 1 = 10 stones, before any spares.

The sand figure covers a 20-30mm sharp-sand bed directly beneath each stone footprint only. Dig the bedding hole a little wider than the stone (20-30mm all round) for levelling room, so buy a touch more than the headline figure. On clay soil use a 30mm bed and a thin sub-base of grit to aid drainage.

A 400mm round or 450mm square stone comfortably fits an adult foot; 600 × 400mm rectangles suit a fast walking path or a wider tread. Natural riven sandstone or limestone costs more than reconstituted concrete but weathers in better. Whatever the shape, set the top flush with the lawn so a mower can pass over it.

Space stepping stones 500-600mm centre to centre, matching an average adult stride. Walk the route first and have someone mark each footfall — that gives the most natural spacing. Use a shorter ~450mm gap for children or older walkers, wider for tall, long-striding adults.

Place the stone, cut around it with a half-moon edger, remove turf to the stone depth plus the sand-bed depth, add and firm the sharp sand, then bed the stone level with or slightly below the grass so the mower clears it.