Concrete Path Calculator
Works out the concrete for a footpath or sidewalk. A path is a long thin slab, which changes the practicalities more than the arithmetic — the volume is small but the pour is spread out.
Includes the waste allowance — this is the figure to order.
Share sends a link that reopens these numbers. Copy details pastes the full breakdown as a list.
The formula
volume = length × width × thickness × (1 + waste)
A slab is a rectangular prism, so the volume is the three dimensions multiplied together. The only judgement in it is the waste allowance — concrete cannot be topped up once it starts curing, so under-ordering is far more expensive than over-ordering.
What to watch out for
A path is the awkward shape in concrete work:
- Small volume, long distance. 10 m of 900 mm path at 100 mm is only 0.9 m³, but it is 10 m of formwork and 10 m of finishing.
- Movement joints matter more. A long narrow slab cracks across itself. Put a joint every 1.5–2 m, or roughly every 2× the width.
- Barrow access decides the method. Ready-mix that cannot reach the far end has to be barrowed anyway — at which point bags mixed near the work can be less effort, not more.
- Crossfall, not camber. A slight slope to one side, around 1:60, sheds water without needing a crown.
Frequently Asked Questions
How wide should a concrete path be?
600 mm for a single-file utility path, 900 mm for a comfortable garden path, 1.2 m if two people walk side by side or you need wheelchair access.
How thick should a garden path be?
100 mm (4 in) over compacted hardcore. Increase to 150 mm only where vehicles cross, such as where a path meets a driveway.
How far apart should joints be in a path?
Roughly twice the width — so every 1.8 m on a 900 mm path. Concrete shrinks as it cures, and a joint decides where it cracks instead of leaving it to chance.
How much concrete for a 10 m path?
A 10 m × 900 mm path at 100 mm needs 0.9 m³ before waste, about 1 m³ ordered — right at the ready-mix minimum, or roughly 72 × 25 kg bags.