Set the spacing to your stride
A stepping stone path only works if your feet land on the stones without shuffling or stretching. Centenary Landscaping Supplies, a Brisbane landscape yard, uses a simple method in its how-to guide:
- From the start of the path, walk about ten comfortable steps along the route.
- Measure the distance and divide it by ten. That is your average step, centre to centre.
- Subtract the stone size to get the gap. A 600 mm step with 400 mm stones leaves 200 mm between them.
Centenary recommends gaps of 100–200 mm, enough for pebbles or a low groundcover between the stones. Its table for a 5 m path with 400 mm stones:
| Step | Gap | Stones (path ÷ step) | Whole stones that fit |
|---|---|---|---|
| 500 mm | 100 mm | 10 | 10 |
| 600 mm | 200 mm | 8.33 | 8 |
| 700 mm | 300 mm | 7.14 | 7 |
The guide divides the path length by the step. The calculator counts whole stones that fit between the ends of the path. The two agree once you round down and spread the spare length. If several people use the path, pace it with the shortest regular stride. A slightly short step is comfortable for everyone, and a long one is not.
How the count works
pebbles (m³) = ( path length × path width − stone area ) × depth
The first stone starts at the beginning of the path and each step adds one, until the next stone would run past the end. On a 5 m path with 400 mm stones and a 600 mm step, that is ⌊4.6 ÷ 0.6⌋ + 1 = 8 stones, with 400 mm left over. Shift the whole line 200 mm along so the spare is shared between the two ends.
Stone size. Centenary calls 400 mm the best size for a stepping stone, because it fits an adult foot and looks in scale with pebbles between. Round stones of the same size give a little less to stand on: a 400 mm round stone has about 78 % of the area of a 400 mm square one.
Laying them so they stay put
Centenary advises against laying stepping stones on bare earth or sand, because they move and discolour. It recommends a wet mortar bed instead:
- Plan the drainage. Grade the ground away from the house, and on a steep slope consider terracing rather than laying stones on the incline.
- Set a string line along the path about 1 mm above the finished height of the stones.
- Dig out enough for about 20 mm of mortar plus the stone. For a 40 mm paver, that means the string sits about 60 mm above the dug ground.
- Mix mortar at 5 parts sand to 1 part cement, or use premixed mortar. One bag beds about 3–4 stones of 400 × 400 mm.
- Bed each stone on the wet mortar, press or tap it down to the string line, and check it is level both ways.
- Finish with weed mat between the stones and a top layer of decorative pebbles.
For a path people walk every day, or one that carries a wheelbarrow, a continuous paved path is easier. The paver calculator covers the base, bedding sand and joints. A concrete path should be at least 75 mm thick.
Stepping stone questions
How far apart should stepping stones be?
Space them to your own step: walk ten comfortable steps, measure and divide by ten. That is the centre-to-centre spacing. With 400 mm stones, a 600 mm step leaves 200 mm gaps. Centenary Landscaping recommends gaps of 100–200 mm.
How many stepping stones do I need for a 5 metre path?
With 400 mm stones: 10 at a 500 mm step, 8 at a 600 mm step and 7 at a 700 mm step. Measure your own step first, because it decides the count.
What size should stepping stones be?
About 400 mm across suits most paths. It fits an adult foot comfortably and looks in proportion with pebbles between the stones. Use larger stones, or two side by side, for a wider path.
What do you lay stepping stones on?
A bed of wet mortar about 20 mm deep, mixed at 5 parts sand to 1 part cement, over levelled ground. One bag of premixed mortar beds about three or four 400 mm stones. Stones laid on bare earth or loose sand tend to rock and sink.
Sources and method
- Centenary Landscaping Supplies, How to: Stepping stones (2021). Covers the ten-step method, the 400 mm stone, 100–200 mm gaps, the 5 m path table, the mortar bed and mix, and mortar bags per stone. The calculator counts one bag for every three 400 mm stones, about 0.48 m² of stone per bag.
- Decorative pebble density (1.55 t/m³) and top-layer depths as on the GardenMaths gravel calculator.
Written by DueRiva · Last reviewed 24 September 2026 · Report an error