Paver Bedding Sand Calculator
Written by Thierno Sadou Diallo, formula verified per our methodology • Last checked on 9/9/2026
The sand volume for a bedding layer is calculated with surface area × thickness. For a 20 m² patio with a 4 cm bedding layer, about 0.8 m³ of sand is needed, roughly 1.28 tonnes.
Explanation
The bedding sand layer is the thin sand layer that individually laid pavers or slabs rest directly on (without pouring concrete), used to level the surface and settle each unit before joint filling. Its typical thickness varies by intended use: 3 to 5 cm once compacted for a strictly pedestrian patio or path, increased to at least 6 cm under pavers meant to carry vehicle traffic, which bear noticeably heavier loads. This sand bed never replaces a gravel sub-base on unstable or poorly drained ground: the two layers actually complement each other on a well-built job, the sub-base (15 to 25 cm of compacted gravel) providing drainage and overall ground stability, while the sand bed (3 to 6 cm) only handles fine leveling directly under the pavers. Washed, sized river sand (0/4 mm) is the reference material for this technique, with a density generally between 1.4 and 1.7 tonnes per m³ when dry and uncompacted — this calculator uses 1.6 t/m³, the most commonly cited value, keeping in mind that wet or bagged, settled sand can weigh noticeably more for the same volume. If the paved area is part of a larger wood deck project, our deck joist count calculator helps estimate the supporting framework underneath.
Example: a 20 m² patio, 4 cm bedding layer
Inputs
Surface to pave: 20 m². Bedding sand thickness: 4 cm.
Calculation
Volume = 20 × 0.04 = 0.8 m³. Mass = 0.8 × 1.6 = 1.28 tonnes.
Result
About 0.8 m³ of sand, roughly 1.28 tonnes, is needed for this bedding layer.
Frequently asked questions
Can fine gravel replace sand for the bedding layer?
Some professionals do use a sand-gravel mix (often called 0/6.3 or 0/8) for better drainage under pavers, but washed, sized river sand (0/4) remains the most commonly recommended reference material, since it levels more easily with a screed board and better settles pavers into their joints.
Does the sand need to be compacted before laying pavers?
The sand bed is usually leveled with a metal screed board without intensive prior compaction (unlike the gravel sub-base, which must be compacted with a plate compactor): the pavers themselves, once laid and vibrated into place, slightly settle the sand and provide the assembly's final stability.
Why does sand density vary so much between sources?
Because moisture content and compaction level strongly affect sand's apparent density: dry, uncompacted sand weighs about 1.4 to 1.6 tonnes per m³, while the same sand when wet or settled in a bag can reach 1.7 to 2.0 tonnes per m³. This calculator uses the median value commonly cited for dry bulk sand.