Free construction and civil engineering calculators
Concrete, asphalt, earthwork, rebar, masonry and finishing quantities. Metric and imperial, every formula shown, nothing to sign up for.
Popular calculators
- Asphalt Tonnage Calculator Convert a paving area and layer thickness into tonnes of asphalt, using a density you control.
- Concrete Volume Calculator Work out the volume of concrete needed for a rectangular pour, with an allowance for wastage.
- Rebar Weight Calculator Calculate the weight of reinforcement bars from diameter, length and quantity.
- Road Base & Subbase Calculator Calculate compacted volume and delivered tonnage of granular base or subbase, including the bulking allowance between loose and compacted material.
- Excavation Calculator Calculate excavation volume in bank measure and the swelled volume that has to be hauled away.
- Brick & Block Calculator Calculate how many bricks or blocks a wall needs, including walls more than one unit thick, along with the mortar between them.
Browse by category
- Concrete Volume, slabs, footings and bag counts for concrete work, with editable density and wastage.
- Road & Asphalt Asphalt tonnage, granular base, tack coat and prime coat, with density under your control.
- Earthwork Excavation, backfill and trench volumes, including swell and compaction shrinkage.
- Rebar & Steel Bar weights, bar counts and spacing for reinforcement.
- Masonry Brick and block counts with the mortar to lay them.
- Finishing Paint, plaster, render and tiling quantities.
- Surveying & Geometry Areas, slopes, gradients and the conversions between them.
How these calculators work
- Every result shows the formula behind it, so you can check the arithmetic yourself.
- Material densities are inputs you can edit, never constants hidden in the code. Your mix design and your test results beat any published table.
- Wastage allowances are visible and adjustable, not baked silently into the answer.
- Metric and imperial throughout, with tonnes and short tons labelled separately so there is no ambiguity.
- Everything runs in your browser. Nothing is uploaded, and nothing needs an account.
These are quantity and conversion tools for estimating and site work. They do not size structural members and they are not a substitute for a design produced against your local code.
All 20 calculators
- Concrete Volume Calculator Work out the volume of concrete needed for a rectangular pour, with an allowance for wastage.
- Concrete Slab Calculator Size a floor or ground slab: volume, ready-mix load, weight and area, including an edge thickening if there is one.
- Concrete Footing Calculator Calculate concrete for strip footings or a set of identical pad footings.
- Concrete Bags Calculator Convert a concrete volume into the number of pre-mixed bags needed, for small pours where ready-mix is not practical.
- Asphalt Tonnage Calculator Convert a paving area and layer thickness into tonnes of asphalt, using a density you control.
- Road Base & Subbase Calculator Calculate compacted volume and delivered tonnage of granular base or subbase, including the bulking allowance between loose and compacted material.
- Tack Coat Calculator Calculate bitumen emulsion for a tack coat, accounting for dilution and residue content to give the binder actually left on the road.
- Prime Coat Calculator Calculate prime coat quantity for a granular base, including sand blinding if it is used.
- Excavation Calculator Calculate excavation volume in bank measure and the swelled volume that has to be hauled away.
- Backfill Calculator Calculate backfill volume around a structure and the material you need to import, using whichever compaction convention your source figure came from.
- Trench Volume Calculator Calculate trench excavation, pipe bedding and backfill for a pipe run in one pass.
- Rebar Weight Calculator Calculate the weight of reinforcement bars from diameter, length and quantity.
- Rebar Spacing Calculator Work out how many bars fit across a span at a given maximum spacing, and the total bar length for a one-way or two-way mat.
- Brick & Block Calculator Calculate how many bricks or blocks a wall needs, including walls more than one unit thick, along with the mortar between them.
- Mortar Calculator Convert a mortar volume into cement, sand and water quantities for a given mix ratio.
- Plaster Calculator Calculate plaster or render volume for a wall, and the cement and sand it needs.
- Paint Calculator Work out how much paint a wall or room needs, allowing for coats, openings and the coverage rate on the tin.
- Tile Calculator Calculate how many tiles a floor or wall needs, including grout joints and a cutting allowance.
- Area Calculator Calculate the area of a rectangle, triangle, circle or trapezoid, with results in metric and imperial units.
- Slope & Gradient Calculator Convert between percentage grade, ratio, angle and elevation difference for a slope.