AsphaltCalc

Stone calculator

Stepping Stone Calculator

Stepping stone spacing is set by human stride, not aesthetics. Enter your path length to get the count that walks comfortably.

Flagstone and cobblestone patio being set on a compacted crushed stone base with a fire pit ring, as measured by a stone patio calculator
Most of the material on a patio job is invisible once it is finished: the base and bedding layers routinely outweigh the visible stone three to one.

Your project

ft
inches

Centre-to-centre spacing. Average adult stride is 24-26 inches.

inches
$

Stepping stones needed

16

stones

Centre-to-centre spacing
24"
Gap between stones
6"
Total stone area
36 sq ft
Setting bed (2" screenings)
0.22 cu yd
Estimated stone cost
$288

Set each stone so its surface sits flush with or 1/4 inch below the surrounding grade. Proud stones are trip hazards and lawnmower killers.

The shareable link reopens this calculator with your exact inputs.

Spacing is a stride problem

Comfortable walking spacing is 24 inches centre to centre for an average adult — that puts the next stone exactly where the foot lands. Anything over 26 inches forces a stretch, anything under 20 makes people shuffle.

Measure your own stride on a lawn to confirm: walk normally, mark two consecutive heel strikes and measure between them. Then set the stones so a step lands mid-stone, not on the edge.

Setting stones so they stay level

Excavate to the stone thickness plus 2 inches, bed on screenings or coarse sand, and tamp each stone down with a rubber mallet until it does not rock. Stones set straight into topsoil sink unevenly within a season.

In lawns, set stones flush with grade so a mower passes over. In beds and gravel, set them 1/4-1/2 inch proud so surrounding material does not wash over the surface.

Stone patio calculator diagram of a cross-section showing compacted subgrade, crushed stone base, bedding sand and flagstone with each layer depth
A patio is three ordered layers. Base depth drives almost all of the tonnage, bedding sand is a thin constant, and only the top layer is the stone you actually see.

Stones needed by path length

At 24 inch centres.

Path lengthStonesStone area at 18" square
10 ft613.5 sq ft
20 ft1124.8 sq ft
30 ft1636 sq ft
50 ft2658.5 sq ft
75 ft3885.5 sq ft

Frequently asked questions

+How far apart should stepping stones be?

24 inches centre to centre for a comfortable adult stride, giving roughly a 6 inch gap between 18 inch stones.

+How many stepping stones do I need?

Path length in inches ÷ spacing, plus one. A 30 ft path at 24 inch centres takes 16 stones.

+What goes under stepping stones?

Two inches of compacted screenings or coarse sand. Setting them directly on soil lets them rock and sink.

+How thick should stepping stones be?

Two inches minimum for natural stone set in soil or grass, 1.5 inches if they sit on a compacted base. Thinner stones crack under a heel strike.