Bitumen Calculator
Built for road and waterproofing crews: enter the surface area, application rate or thickness, and bitumen density, and it returns the quantity in litres, tonnes and standard drums. A wastage factor is included, because spray losses on prime and tack coats are real and rarely budgeted.
Bitumen required
| Volume | |
| Mass | |
| Material cost | — |
Rounding: drum count rounds up; cost is computed from the unrounded mass. Density default 1.02 kg/L, paving-grade at ambient.
One material, three units of sale
Bitumen changes its unit of account depending on who is buying. A waterproofing crew thinks in litres and drums; a road authority tenders in tonnes; a data sheet specifies film thickness in millimetres. All three describe the same black binder, linked by the near-unity density of about 1.02 kg per litre — and most ordering mistakes in this trade are simply conversions done in a hurry between those three languages.
The geometry side is mercifully simple: film thickness times area, because coating a surface is just spreading a very flat prism across it. The subtlety is that porous substrates cheat the geometry — bare concrete drinks a first coat of primer well beyond the calculated film — which is why waste here covers absorption, kettle residue and lap joints rather than the spillage that dominates other materials on this site.
How to use the bitumen calculator
- Pick the unit system. Bitumen work is quoted metric almost everywhere — square metres and millimetres — but the imperial mode accepts square feet and inches and converts internally.
- Enter the coated area. The full surface receiving bitumen: roof deck, foundation wall, tanking pit. Include upstands and returns, which are easy to drop from a plan-view takeoff.
- Set the applied thickness. Hot-applied membranes run about 2–3 mm per coat; brush-applied damp-proofing is thinner, mastic filling far thicker. Use the specified dry film thickness where a spec exists.
- Confirm the density. Paving and industrial grades sit near 1.02 kg per litre at ambient temperature; your supplier's data sheet value can replace the default.
- Add waste. Absorption into porous substrates, kettle residue and edge overlap all consume material beyond the geometry — 5% is a workable floor.
- Read litres, tonnes and drums together. Small jobs buy 200 L drums, bulk work is invoiced by the tonne — the tool reports the same quantity in every unit the trade uses.
Key formulas
- Volume: V (m³) = area (m²) × thickness (mm) ÷ 1,000, × (1 + waste%)
- Litres: L = V × 1,000 — equivalently, L/m² = thickness in mm
- Mass: tonnes = L × density (kg/L) ÷ 1,000
- Drums: ⌈ L ÷ 200 ⌉
Worked example
A 200 m² basement raft receiving a 3 mm hot-applied membrane with 5% waste: V = 200 × 0.003 = 0.600 m³ = 600 L; with waste 630.00 L. Mass = 630 × 1.02 ÷ 1,000 = 0.64 tonnes; drums = 630 ÷ 200 → 4 drums. Switch the tool to metric, enter the same values, and each figure reproduces.
Typical application rates
| Application | Typical film | ≈ L/m² |
|---|---|---|
| Prime coat (spray) | — | 0.2–0.4 (specified rate) |
| Damp-proof coating (brush) | ≈1 mm | ≈1 per coat |
| Hot-applied membrane | 2–3 mm | 2–3 |
| Mastic / joint filling | varies | by joint volume |
Indicative trade practice; a project specification or product data sheet overrides this table wherever one exists.
Things to keep in mind
- Prime porous substrates first. A thin primer coat seals the suction so the membrane coat builds to its designed thickness instead of vanishing into the concrete.
- Respect application temperature. Hot grades handle at 150–180°C — undersized kettles and long carries cool the material below workable viscosity.
- Laps are part of the area. Multi-pass and multi-coat systems overlap; the waste allowance is where those laps live in the arithmetic.
- Drums are heavy and awkward. A full drum tops 200 kg — plan the crane or the drum dolly before delivery day, not after.
- Protect finished membranes. Backfill and foot traffic tear fresh bitumen; protection board is cheaper than re-tanking a buried wall.
Frequently asked questions
How many litres of bitumen per square metre?
Multiply thickness in millimetres by one: a 1 mm film takes 1 litre per square metre, a 3 mm membrane 3 L/m², before waste. That tidy relationship exists because a litre is exactly a millimetre spread over a square metre. Spray applications like tack coats are specified directly in rates instead — typically 0.2–0.4 L/m² — because their films are too thin to measure as thickness.
How much does bitumen weigh per litre?
Paving-grade bitumen runs close to 1.02 kg per litre at ambient temperature — marginally denser than water — with specification ranges spanning roughly 1.01 to 1.06 depending on grade and source crude. The tonnage line in this tool multiplies your litres by that density, which is why a full 200 L drum weighs a little over 200 kg plus the steel.
How many square metres does one drum of bitumen cover?
A standard 200 L drum covers about 100 m² at a 2 mm film, or roughly 65 m² at 3 mm, before allowing for waste and substrate absorption. Divide 200 by your thickness in millimetres for the quick version. Porous concrete and masonry drink the first coat noticeably, so real-world first-coat coverage lands below the arithmetic and the second coat above it.
What is the difference between bitumen and asphalt?
Bitumen is the black viscous binder itself — refined from crude oil. Asphalt (in most of the world, "asphalt concrete") is the composite of bitumen mixed with graded stone aggregate, which is what actually paves roads. This calculator sizes the pure binder for membranes, priming and sealing; the asphalt calculator on this site handles the mixed paving material by the ton.
How is bitumen applied for waterproofing?
Three broad families: hot-applied (kettle-melted and mopped or squeegeed, building thickness fast), cold-applied cutbacks and emulsions (brush or spray, thinner films, no kettle), and self-adhesive or torch-on membrane sheets where the bitumen arrives pre-formed. Thickness-based estimating suits the first two; sheet systems are bought by the square metre of roll instead.
Does temperature change how much bitumen I need to order?
Not meaningfully for quantity — thermal expansion shifts volume a few percent between ambient and application temperature, which is why supply contracts specify the measurement temperature, but your order in tonnes is temperature-proof since mass does not expand. Where it does matter is logistics: hot-applied work needs the material at 150–180°C, so drum count also implies kettle cycles.
Last updated: 24 July 2026