What this site is
A free rebar estimating tool for concrete slabs, walls and footings. You enter the dimensions, bar size and spacing; it returns bar counts, total length, lap allowance, total weight and a cost estimate.
It runs entirely in your browser. Nothing you type is uploaded, and there is no account to create.
Who it is for
- Contractors and crews pricing up a pour
- Estimators and quantity surveyors doing a quick cross-check
- Owner-builders and DIYers who want to order the right amount of steel
- Students learning how a bar schedule is put together
How the numbers are worked out
Every result comes from the formulas listed on the calculator page. In short:
- Bar count — the clear span is divided by the on-centre spacing, rounded down, plus one bar at each end.
- Total length — individual bar lengths are added up, then lap allowance is added wherever a run is longer than a stock bar.
- Lap allowance — defaults to 40 × bar diameter, a common rule of thumb. You can override it with your own value.
- Weight — derived from the nominal bar diameter and the density of steel (490 lb/ft³).
- Pieces — the number of stock bars to buy, rounding each run up before totalling.
What it does not do
This is an estimating tool, not a design tool. It does not check your structure, and it is not a substitute for a stamped drawing, a local building code, or an engineer's bar schedule. Lap lengths, cover, hook lengths and anchorage requirements vary by code and by application — always confirm against the specification for your job before you order or place steel.
- No structural analysis, load calculations or code compliance checks
- No bent-bar geometry, hooks, or stirrup and tie take-off
- No waste factor — add your own allowance on top
Why it is free
This site is free to use and carries no advertising. It is paid for by affiliate commissions: if you buy material through one of the links on the calculator page, we may earn a commission from the retailer. That costs you nothing extra and does not change the price you pay. Affiliate links are always labelled as such, and they never influence the calculations.
Who runs it
Rebarcount is an independent, one-person project. Questions, corrections and bug reports are genuinely welcome — see the contact page.
Page last reviewed: 17 September 2026