Self binding gravel calculator
Work out how much self binding gravel a path, courtyard or driveway needs, in tonnes, cubic metres or bulk bags.
Self binding gravel calculator
Work out how much self binding gravel a path, courtyard or driveway needs, in tonnes, cubic metres or bulk bags.
Enter your dimensions to see how much gravel you need.
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Results are estimates for planning. Bulk density varies by supplier, moisture and how much the material is compacted, so confirm quantities with your supplier before ordering.
Self binding gravel calculator
What self binding gravel is
A blend of small angular stones and fine clay or dust that compacts down to a firm, semi permeable surface. It looks like a loose gravel but behaves like a soft bound path, which is why it is a common choice for National Trust and country garden paths in the UK. Once rolled it holds shape underfoot and drains without puddling.
Depth and compaction
Self binding gravel is normally laid 40 to 50 millimetres deep when compacted, over a compacted MOT type 1 sub base for paths and 100 to 150 millimetres of sub base for driveways. Loose depth before rolling is about 25 percent more than finished depth, so a 40 millimetre finished path is laid to 50 millimetres before compaction.
Bulk bags and loose loads
A standard 850 kilogram bulk bag of self binding gravel covers about 10 to 12 square metres at 40 millimetres finished depth. Larger jobs come loose by the tonne, delivered by tipper. The calculator returns the tonnage against your chosen compacted depth, plus the ten percent overage that covers compaction loss and edges.
Building a self binding gravel surface
This calculator uses the same area times depth logic as the rest of the site, but self binding gravel behaves differently once it is down from the loose decorative stone most of the other gravel pages cover. The fines mixed through it are what let the surface set into a firm, walkable crust rather than staying loose underfoot, so the quantity you calculate here is only half the job; how it is compacted and allowed to set matters as much as how much you order, and skipping that part of the install is the most common reason a self binding surface stays loose and dusty instead of setting hard.
Self binding gravel sits in the same general family as crusher run and Class 5 base material, in that all three rely on a graded mix of stone sizes down to fine dust to lock together rather than relying on a binder added separately. If you are weighing it against a compacted crushed stone base instead of a self binding surface, this explainer on crusher run covers how that related material achieves the same locking effect, and the Class 5 gravel calculator is worth a look if your project is really a load bearing base course rather than a finished walking or driving surface, since the two materials are sized and sold slightly differently even though they work on the same principle. What sets self binding gravel apart is that it is usually sold specifically as a finished surface material, graded and blended with that end use in mind rather than as a generic base aggregate.
Compaction technique matters more here than for a decorative gravel bed. Self binding gravel is typically laid and compacted in shallow lifts rather than one deep pour, and the mix needs to be close to its working moisture content when it is compacted, since a surface that is compacted too dry will not bind and one that is too wet will push and rut under the roller or plate instead of locking. This guide to compacted versus loose aggregate covers the broader principle of why the material you order is not the same volume as what ends up on the ground once it has been through this process, and the same logic applies whether the lift is a few centimetres or a full base course deep.
Whether you are building a driveway or a path and courtyard surface changes how much margin is worth building into the order. A driveway self binding surface generally needs a more robust depth and a proper sub base beneath it to handle vehicle weight, which the gravel driveway calculator is built around, while a garden path or courtyard can often get away with a shallower depth over compacted subgrade, closer to what the patio gravel calculator assumes for foot traffic only areas. Matching the depth to the actual load the surface will carry, rather than defaulting to a single figure for every use, is what keeps the finished surface from rutting under whatever eventually drives or walks on it. A gentle camber or fall across the width of the finished surface also helps shed surface water before it has a chance to soften the top layer in a wet spell.
Self binding gravel generally costs more per tonne than a plain decorative or crushed stone because of the extra processing in the mix, so it is worth running your total through the gravel cost calculator before committing, and comparing it against a standard crushed stone base from the crushed stone calculator if budget is tight and a self binding finish is not essential to the project. Keeping a small amount of the same batch aside after installation also makes any future patch repairs blend in better, since the color and fines content of self binding gravel can vary noticeably between deliveries, and a patch laid with a mismatched batch tends to stand out visibly even once it has bound and settled in.
Frequently asked questions
How deep should self binding gravel be laid?
40 to 50 millimetres compacted for a path, or 50 millimetres compacted for a driveway top layer over a properly compacted sub base. Below 40 millimetres the surface breaks up under foot traffic; deeper than 60 millimetres does not add durability once compacted.
Does self binding gravel need a sub base?
Yes, for anything driven on or walked heavily. MOT type 1 sub base at 100 to 150 millimetres compacted for a driveway, or 75 to 100 millimetres for a path. Without a sub base the surface deforms under load and puddles where the ground below is soft.
How much does a bulk bag of self binding gravel cover?
About 10 to 12 square metres at 40 millimetres compacted depth for a standard 850 kilogram bag. Coverage falls to about 8 square metres at 50 millimetres compacted, because roughly a quarter of the loose depth is lost to compaction.
What is the difference between self binding gravel and normal gravel?
Self binding gravel has fine clay dust mixed through it that binds the stones together when rolled and watered. Normal 20mm gravel is washed clean of fines, so it stays loose forever. The two look similar in the bag but behave very differently once laid.
Can self binding gravel be used on a driveway?
Yes, with a proper sub base. Many rural and heritage properties use it precisely because it looks softer and quieter than tarmac while still coping with light vehicle traffic. Heavy commercial traffic wears it faster than tarmac.
How often does self binding gravel need topping up?
A well laid path needs a light rake and topping every three to five years, or sooner in a driveway. Water helps the fines re bind after a top up. Weeds occasionally break through and are best removed by hand rather than herbicide.
Do I need edging for self binding gravel?
Yes. Without a firm edge the gravel spreads sideways under load, thinning the surface at the middle. Timber, steel or brick edging works; the edging is also what lets you get the surface to a level finish during laying.
What is the compaction loss with self binding gravel?
Roughly 20 to 25 percent of the loose depth. So to end up at 40 millimetres finished, lay to 50 millimetres before rolling, and buy the tonnage for the compacted depth plus the ten percent overage this page already includes.