Disclaimer and safety notice
Safety notice: Material planning only
What these calculators do
They convert the dimensions you enter into material quantities, purchase units, approximate weights and — from prices you supply — approximate costs. That is the whole of what they do.
What they do not do
- Size structural members such as joists, beams, lintels or reinforcement
- Design foundations or assess ground-bearing capacity
- Assess ground conditions, drainage or water table
- Confirm compliance with building regulations, planning permission or local codes
- Assess party wall, boundary or right-of-light implications
- Replace a site survey, an engineer or a building inspector
Work that always needs professional input
Get qualified advice before starting any of the following. In most cases the work is also notifiable.
- Structural decks — particularly raised decks and any deck fixed to a building. A poorly fixed ledger is one of the most common causes of deck collapse.
- Retaining walls — retained ground exerts far more force than people expect, and drainage behind the wall is as important as the wall itself.
- Load-bearing walls — including forming or altering any opening.
- Foundations and footings — depth and width depend on the soil, on nearby trees and on the load.
- Reinforcement design — grade, position, cover and lap lengths are engineering decisions, not estimating ones.
- Drainage — including anything connecting to a public sewer or altering surface water run-off.
- Electrical and gas work — restricted to competent, registered people in both the UK and the US.
Excavation
Before you dig anywhere, check for buried services.
- United Kingdom: Before digging, check for buried services. Free utility plans are available from the relevant network operators, and a cable avoidance tool (CAT) scan is strongly recommended.
- United States: Call 811 before you dig. Utility locating is free in every US state and is required by law in most of them.
Deep or steep-sided excavations can collapse without warning and have killed people working in trenches barely deeper than waist height. Trench support and safe access are specialist matters — this site gives no guidance on them and you should not infer any.
Handling and delivery
Many of the materials estimated here are heavy. A single 600 × 600 mm paving slab is around 28 kg, and anything over 25 kg is a two-person lift. Bulk bags cannot be moved by hand once they are on the ground, and vehicle payload ratings are exceeded far more easily than people assume.
Costs
Every cost figure comes from prices you entered. This site does not hold, quote, scrape or estimate supplier prices, and no figure it produces is a market price or a quotation.
Accuracy of quantities
Assumptions are published with their sources, ranges and review dates on the material densities page. Real materials vary. Check quantities against your own measurements and your supplier’s actual products before ordering, and tell us if something looks wrong.