How many kerbs do I need per metre?

Standard UK precast concrete kerbs are 915mm (just under 1 metre) long, so you need approximately 1.1 kerbs per metre of run. This applies to HB2 half battered, BN bullnosed, SP splayed and flat top edging types. Allow 10% extra for cuts and wastage.

What is haunching concrete for kerbs?

Haunching is the concrete support placed against the back (and sometimes front) of a kerb to hold it in position. It's typically a triangular profile at 45 degrees, applied to the full depth of the kerb. Use C20 concrete (ST2) for haunching. The volume depends on the kerb height — taller kerbs like BN (305mm) need more than edging (150mm).

What concrete mix is used for kerb bedding?

Kerb bedding uses a semi-dry mortar mix of roughly 6:1 (sand:cement) or C12 concrete at 25mm thickness. The kerbs are tapped into the bed to the correct level using a rubber mallet. Haunching is usually ST2 (C20) concrete. For heavy vehicle crossings, use ST4 (C30) concrete.

What is the difference between HB and BN kerbs?

HB (Half Battered) kerbs have a sloped face and are the most common type for roads and driveways (125×255mm cross-section). BN (Bullnosed) kerbs have a rounded top edge and are taller (150×305mm), used where a higher upstand is needed. Both come in 915mm lengths to BS EN 1340.

Do I need kerbs for a driveway?

Kerb edging or similar edge restraint is essential for block paving, resin-bound and gravel driveways to prevent the surface spreading. For tarmac, kerbs define the edge and provide a neat finish. Flat top edging is often sufficient for garden paths, while HB2 kerbs are standard for vehicle crossovers.

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Kerb Edging Calculator — Units, Haunching & Bedding

Calculate kerb units per metre by type, haunching concrete and bedding mortar for kerb installation.

Total Kerb Run

Total length of kerbing required

Kerb Type

BS EN 1340 standard sizes

Kerb Price

Price per kerb unit

Concrete Price

Ready-mix or site-mixed price

How We Calculate This

This calculator determines kerb quantities, haunching concrete and bedding mortar for kerb and edging installation.

Kerb count

Kerb Units = (Total Length / Kerb Length) x (1 + Wastage%)
Standard kerbs are 915mm long. Rounded up to whole units.

Haunching concrete

Haunching Volume = Length x Haunch Width x Kerb Depth x 0.5 x 2 sides
Triangular profile at 45° on both sides of the kerb. Bedding mortar at 25mm depth x 300mm width.

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Last updated: March 2026

All calculations are estimates. Verify with your supplier.