Concrete Kerb and Gutter Calculator - UK Kerb Calculator

Standard Concrete Kerb Sizes in the UK

Concrete kerb stones in the UK come in a handful of standard sizes set out by British Standards. The most common is the half-battered kerb (HB2), measuring 125mm wide × 255mm high × 915mm long. Each one weighs around 68kg, so you will want a mate and a kerb lifter.

Bullnose kerbs are the other popular choice, typically 150mm × 305mm × 915mm. These have a rounded top edge and work well where pedestrians step on and off, like dropped kerb crossings.

Pin kerbs are much smaller, usually 50mm × 150mm × 915mm, and weigh only about 15kg each. They are used for garden edging, driveway borders, and anywhere you need a neat, low-profile concrete kerb edging without heavy machinery.

For a typical 20-metre driveway border using HB2 concrete kerbs, you need 22 kerb stones (20m ÷ 0.915m each). Our concrete kerb calculator works out the exact number based on your measurements.

Concrete Kerb Mix Ratios

Getting the right kerb concrete mix matters for durability. For most domestic kerbing jobs, a 1:2:3 mix (one part cement, two parts sharp sand, three parts 20mm gravel) gives you roughly C25 strength. That is strong enough for driveways, paths, and garden concrete kerbing.

If you are buying ready-mix, ask for C25/30 or GEN3 designation with a 50-75mm slump. A stiffer mix holds its shape better in formwork, which is what you want when casting kerbs in place.

For bedding precast concrete kerb stones, use a slightly wetter mix at 1:3 (cement to sharp sand) for the haunching. Haunching is the concrete you pack around the base and back of each kerb stone to hold it in position. Each metre of standard kerbing needs about 0.02m³ of haunching concrete.

One 25kg bag of cement mixed with sand and gravel produces roughly 0.01m³ of concrete. For 10 metres of in-situ kerb at a 125mm × 255mm cross-section, you need about 0.32m³, which works out to around 31 bags of 25kg concrete. Use our slab calculator if you are also pouring a base alongside the kerbs.

How to Calculate Concrete for Kerb Edging

Calculating concrete for kerb edging is straightforward. Measure the total length in metres, then multiply by the cross-sectional area of the kerb profile. For example, a 50mm × 150mm pin kerb has a cross-section of 0.0075m². Multiply that by 25 metres and you get 0.19m³ of concrete.

Always add 10% for waste. Concrete kerbing involves tight formwork, and some mix will stick to your tools, boards, and the ground around the trench. That 0.19m³ becomes 0.21m³ in practice.

For larger profiles like HB2 kerbs (125mm × 255mm), the cross-section is 0.032m². A 30-metre run needs 0.96m³ plus 10% waste, so you would order 1.06m³ of ready-mix. At around £100-£140 per m³ delivered, that is £106-£148 for materials alone.

Our concrete kerb calculator does this maths instantly. Enter your kerb length and profile dimensions, and it shows total volume in cubic metres, bags needed, and estimated cost. No need for a spreadsheet or a calculator app.

Types of Concrete Kerbs for Different Projects

Half-battered kerbs (HB1 and HB2) are the standard choice for UK roads and driveways. The angled face helps with drainage, directing rainwater into the gutter channel. HB2 is the larger option and suits roads with heavier traffic.

Bullnose concrete kerbs have a smooth, rounded top. You see them at dropped kerb crossings, pedestrian areas, and residential streets where a softer edge looks better. They are also used in car parks where vehicles might clip the kerb.

Concrete pin kerbs are the go-to for garden concrete kerbing and light domestic work. At 50mm × 150mm, they sit low to the ground and create a clean boundary between lawn and patio or between gravel and flower beds. A 20-metre garden border using pin kerbs needs about 0.15m³ of concrete.

Flush kerbs sit level with the road surface and are common in shared-surface housing estates. Channel kerbs act as shallow gutters, directing surface water to drain points. For any of these concrete kerb profiles, enter the dimensions into our footing calculator if you need to work out the foundation concrete separately.