How Much Material Do I Need for My Surface?

Typical Coverage Rates for Pebbles and Resin

As a rule of thumb, a 25 kg bag of washed pebbles is designed to cover approximately 1 m² at a typical outdoor installation depth. The amount of resin needed will depend on factors such as the aggregate type, granule size, and intended thickness of the finished layer. For standard surfaces, plan on pairing each 25 kg pebble bag with the recommended resin volume from your chosen system.

• For coloured or natural pebbles, resin is usually added at a ratio of around 3% of resin to stones by weight.
• Always use the specific guidance provided for your chosen resin kit, as requirements may vary by product.

Measuring Your Surface and Calculating Needs

Start by carefully measuring your project area. Multiply the length by the width (in metres) to calculate square metres to be covered. Then, use the product guidance to determine how many 25 kg pebble bags and the corresponding resin amount are required. For example, a 12 m² driveway would typically need 12 bags of pebbles and the resin specified for that total weight.

If you are planning a resin-bound surface for a driveway, patio, or path, consider the intended thickness—usually around 15–20 mm for outdoor loads. Thicker layers or challenging sub-bases may require extra material. A complete kit like the Flowstone Permeable Floor Kit includes all calculations for area-based ordering, helping avoid miscalculation.

When Accuracy Matters Most

Getting your material estimate right is particularly important for larger or load-bearing areas such as driveways, where underestimating can delay the project and affect the final result. It’s also key when using coloured pebbles, as binder ratios and coverage may differ slightly from standard aggregates. Always consult the specific product instructions and round up when in doubt.