Stones needed at 24 in center-to-center spacing
stones = roundup(path length in inches / 24) + 1, for one straight run. Figure branching paths as separate runs. Non-even lengths round up, then the gaps tighten slightly across the run.
| Path length | Spaces at 24 in | Stones needed |
|---|---|---|
| 6 ft | 3 | 4 |
| 8 ft | 4 | 5 |
| 10 ft | 5 | 6 |
| 12 ft | 6 | 7 |
| 15 ft | 8 | 9 |
| 20 ft | 10 | 11 |
| 25 ft | 13 | 14 |
| 30 ft | 15 | 16 |
| 40 ft | 20 | 21 |
| 50 ft | 25 | 26 |
Concrete per cast stone, 2 in thick
Volume = footprint x 2 in. Bags per stone use the QUIKRETE Concrete Mix No. 1101 yields of 0.30 / 0.45 / 0.60 cu ft for 40 / 60 / 80 lb bags. Multiply by your stone count, add waste, then round up to whole bags once per bag size (not per stone).
| Stone (2 in thick) | Volume (cu ft) | 80 lb bags | 40 lb bags |
|---|---|---|---|
| 12 in round | 0.13 | 0.22 | 0.44 |
| 12 in square | 0.17 | 0.28 | 0.56 |
| 16 in round | 0.23 | 0.39 | 0.78 |
| 16 in square | 0.30 | 0.49 | 0.99 |
| 18 in round | 0.29 | 0.49 | 0.98 |
| 18 in square | 0.38 | 0.63 | 1.25 |
| 24 in square | 0.67 | 1.11 | 2.22 |
Stone size vs gap at 24 in centers
Gap = 24 minus stone width. Keep edge gaps near 3–6 in where possible. When the gap grows much past 10 in, tighten the centers instead of stretching the walker.
| Stone width | Gap at 24 in centers | What it feels like |
|---|---|---|
| 12 in | 12 in | A hop for most people – consider 18–20 in centers (6–8 in gap) instead |
| 16 in | 8 in | Comfortable stride path; the default in this calculator |
| 18 in | 6 in | Comfortable, at the top of the 3–6 in edge-gap guidance |
| 24 in | 0 in | Stones butt together and the path becomes a continuous walk |
Stepping stone formats stocked at the big boxes
Representative SKUs checked August 2026, and availability and price vary by store. All are plain drycast or wetcast concrete in gray or pewter. A dash means the spec isn’t published in the listing.
| Size and shape | Example product | Thickness | Store |
|---|---|---|---|
| 12 in round | Pavestone Pewter Round Concrete Step Stone, model 71319 | 1.75 in | Home Depot |
| 12 in square | Pavestone Pewter Square Concrete Step Stone, model 71200 | 1.5 in | Home Depot |
| 16 in round | Mutual Materials Round Exposed Aggregate Concrete Stone | – | Home Depot |
| 16 in square | Pavestone Pewter Square Concrete Step Stone, model 72600 | 1.77 in | Home Depot |
| 18 in square | Yorkstone Square Gray Concrete Patio Stone, item 104970999 | 2 in | Lowes |
| 24 in square | Square Gray Concrete Patio Stone, item 104772999 | 2 in | Lowes |
| Cast your own, 2 ft x 2 ft pattern | QUIKRETE Walk Maker reusable form – one 80 lb bag per placement | 2 in | Home Depot / Lowes |
How the count works
Stones = path length divided by center-to-center spacing, rounded up, plus one for the starting stone. Spacing is measured center to center because your foot lands in the middle of each stone. The gap you see between the edges is just what’s left over once the stone itself is accounted for.
A 20 ft path is 240 in. At 24 in centers that’s 240 / 24 = 10 spaces, plus the start stone, so 11 stones. When the division doesn’t come out even, round up first. The last stone then lands at or just past your end point, and you tighten the gaps a little across the run to absorb the difference.
Where 24 in comes from (and what it isn’t)
No building code or ANSI standard governs stepping stone spacing in a garden path. The 24 in center-to-center figure is a trade convention. Paver manufacturers such as Western Interlock publish it as the spacing that suits most people, since a relaxed adult walking step usually runs about 2–2.5 ft. Treat it as a starting point rather than a rule, and walk a dry layout before anything gets dug in.
Two adjustments are worth knowing. Shorter walkers and children tend to be more comfortable at 18–20 in centers, and long-legged walkers may prefer 26 in. Who walks the path most? Set the spacing for them.
The edge gap also matters on its own, separately from the centers. With small stones, 24 in centers leave a 12 in stretch of bare ground, and that starts to feel like a hop. Manufacturer guidance is to keep 3–6 in between edges where you can, which is why 16–18 in stones are the sweet spot for a true stride path.
Stone sizes you can buy off the shelf
The big boxes stock rounds and squares at 12, 16, 18 and 24 in, in plain gray or pewter drycast concrete. Thickness is typically 1.5–2 in, depending on the line.
Real examples include the Pavestone 12 in round, 12 in square and 16 in square step stones, plus the Mutual Materials 16 in round exposed-aggregate stone, all at Home Depot. Lowes carries the 18 in and 24 in square gray patio stones. Model numbers and thicknesses are in the formats table above.
Singles run a few dollars each at US big-box stores as of August 2026, so a path is usually cheaper bought as stones than cast, once bags, molds and your time are priced in.
A 24 in square is really a patio slab doing stepping stone duty. At 24 in centers its gap is zero. The stones butt edge to edge and the path becomes a continuous walk, which may be just what a wheelbarrow route needs.
Casting your own
Volume per stone is footprint times thickness. A 16 in square cast 2 in thick is 1.78 sq ft x 0.167 ft = 0.30 cu ft.
That works out to exactly one 40 lb bag of concrete mix, or half of an 80 lb bag. The bag yields this calculator uses come from the QUIKRETE Concrete Mix No. 1101 data sheet (the same figures as the table note above), and that sheet lists stepping stones as an intended use.
The same sheet also sets the floor on thickness, since the mix is designed for placements 2 in and up, so do not cast a stone thinner than 2 in.
The QUIKRETE Walk Maker is the packaged version of this math. It’s a reusable 2 ft x 2 ft x 2 in multi-cavity form that takes one 80 lb bag per placement, per the Walk Maker data sheet. Single-stone molds sold online usually run 12–18 in across and about 2 in deep. The same footprint-times-thickness arithmetic applies to any of them.
Base prep for a lawn path
A stepping stone in a lawn doesn’t need the full paver-patio base stack. The common approach is to cut around a dry-laid stone with a spade, lift the sod, excavate to stone thickness plus 1–2 in, and screed in 1–2 in of coarse sand or paver base sand to level and drain.
Set the top flush with grade, or just above the soil but below mower-blade height, so the mower passes over it. Stones settle a little in the first season. A sand bed makes lifting and releveling a five-minute job instead of a dig.
Setting stones directly on firm, well-drained cut grade also works, and it’s how many garden paths get built. Expect a bit more seasonal movement and rock that way. Save compacted gravel for wet sites, clay, or paths that carry wheelbarrow and cart traffic. If you’re unsure what your ground needs, check with your local supplier about the bedding sand they recommend.
Common questions
How many stepping stones do I need?
For a typical 20 ft path, 11 stones. The sum is 240 in divided by 24 in center spacing, giving 10 spaces, plus one for the start stone. The general rule is path length divided by center-to-center spacing, rounded up, plus one. The table on this page covers the common lengths.
How far apart should stepping stones be?
Most adults are comfortable at 24 in center to center. It’s a trade convention matched to a relaxed walking step of about 2 ft, published by paver manufacturers such as Western Interlock, and no code or ANSI standard governs it. Note that’s center spacing, not the gap (a 16 in stone on 24 in centers leaves an 8 in gap). Use 18–20 in centers for shorter walkers and keep edge gaps near 3–6 in where stone size allows.
How much concrete do I need for one stepping stone?
0.30 cu ft for a 16 in square stone cast 2 in thick, which is one 40 lb bag on the nose, or two stones per 80 lb bag at its 0.60 cu ft yield. A 12 in round at 2 in takes 0.13 cu ft, so one 80 lb bag casts four. The yields come from the QUIKRETE Concrete Mix No. 1101 data sheet.
How many bags of concrete do I need for a stepping stone path?
For a 20 ft path of eleven 16 in square stones cast 2 in thick, figure 6 bags of 80 lb mix. The sum is 11 x 0.296 cu ft x 1.05 waste = 3.42 cu ft, divided by 0.60 cu ft per bag = 5.7, rounded up to 6. Use the per-stone volume table on this page for other sizes and bag weights.
Can I lay stepping stones directly on dirt?
Yes, on firm, well-drained soil. Cut the outline, dig out sod and soil to sit the stone flush, tamp, and set it. A 1–2 in sand bed adds roughly one 50 lb bag per one to three 16–18 in stones. One bag covers six 12 in stones on a 1 in bed, while a 24 in stone on 2 in eats more than a bag each. Most install guides specify the bed since it makes leveling and adjustment easier.
What size stepping stone is best?
16–18 in across. It’s the smallest size with some margin for a full adult footfall, and at 24 in centers it leaves a 6–8 in gap (at or just past the 3–6 in edge-gap guidance). 12 in stones work but demand precise foot placement at stride spacing. 24 in squares butt together at 24 in centers and read as a solid walk.