Rebar Estimator
Estimate reinforcement for nine element types: bar counts, cutting lengths and stirrups, a lap and waste allowance you set, and tonnage by diameter and by element.
Bar masses are the ISO 6935-2 Table 2 values as printed. Mesh and wall bars are counted over the clear length between covers, rounded up, ⌈(L − 2c)/s⌉ + 1, so no space exceeds the spacing entered; stirrups and ties are counted the same way over the member length. Cut lengths are the clear dimension plus any end legs, less 0.5r + d per 90° bend (BS 8666, r from the EN 1992-1-1 mandrel). A closed stirrup is its outside perimeter at the cover line plus two 135° hooks of max(6d_b, 75 mm), per ACI 318-19 Table 25.3.2.
Element and detailing
Element sketch
| Steel mass | — |
|---|---|
| Concrete volume | — |
| Ratio | — |
—
Bar bending schedule: this element
| Mark | Position | Shape | Ø | Dimensions (mm) | No. of bars | Cutting length (m) | Total length (m) | Net mass (kg) |
|---|
A, B, C: bar dimensions to the outside of the bar; h: straight extension of each 135° hook; D: helix centreline diameter; p: pitch; n: turns. The cutting length includes the bend deduction and both hooks.
Stock bars to order
| Diameter | Pieces | Cut length (m) | Stock bars | Stock mass (kg) | Offcut |
|---|
Cumulative schedule
| # | Element | Dimensions | Detailing | m³ | kg | kg/m³ | Remove line |
|---|
No lines yet: detail an element, then add it.
Diameter summary for procurement
| Diameter | Mass (kg) | Mass (t) | Share | Stock bars |
|---|
Average ratio by element type
| Element | Lines | Average (kg/m³) | Published range |
|---|
Units: dimensions in metres unless stated, diameters, spacings and cover in millimetres. Bar masses are the ISO 6935-2 Table 2 values as published, and are not rounded before summing. Ratios are shown to the nearest kg/m³.
Questions engineers ask
Is a lap length really 40d, or 50d?
Those two rules of thumb were looked for in ACI 318 and EN 1992 and are in neither, so this tool does not use them. ACI 318-19 Table 25.5.2.1 gives a Class B tension lap of 1.3ℓ_d with a 300 mm minimum; IS 456:2000 cl. 26.2.5.1 gives the greater of ℓ_d and 30φ. The lap allowance here is a percentage you set, and it is your number.
How is the bend deduction worked out?
From the BS 8666 shape-code formulas, which take the dimensions to the outside of the bar and deduct 0.5r + d at each 90° bend, r being the minimum scheduling radius. That radius is half the EN 1992-1-1 Table 8.1N mandrel diameter: 4φ up to 16 mm and 7φ above. The deduction is therefore 2d per bend up to 16 mm and 2.75d above. It applies only where you give an end leg; with an end leg of zero the bar is straight.
How are the bars counted?
Bars in a mesh or a wall face are spread over the clear length between the two covers, with a bar at each end, and the count is rounded up: n = ⌈(L − 2c)/s⌉ + 1, so no space is wider than the spacing entered. Stirrups and ties are counted the same way over the member length; with closer zones at the ends, each zone and the middle are counted separately, and a support spacing or zone length of 0 means uniform spacing. The cover must leave a positive clear dimension, or nothing is computed.
How long is a closed stirrup?
Its outside perimeter at the cover line plus two 135° hooks, each with the straight extension of ACI 318-19 Table 25.3.2: the greater of 6d_b and 75 mm. In a 300 × 600 mm beam with 40 mm cover and a Ø10 stirrup that is 2(0.220 + 0.520) + 2 × 0.075 = 1.630 m, because 6 × 10 = 60 mm is less than 75 mm. Stirrup diameters are offered up to 25 mm, the range of that table.
How reliable is the kilograms-per-cubic-metre ratio?
It is the softest number in the tool and it is labelled as such. There is no code figure for kg/m³. The band comes from a widely reproduced estimating table, cross-checked against The Concrete Centre's CCIP-025, whose rates were back-calculated from real Eurocode 2 designs and run consistently lower for suspended slabs. For bored piles no published figure was found at all, so what is shown is the EN 1992-1-1 9.8.5(3) minimum-percentage floor, labelled a floor.
Does the estimator design the reinforcement?
No. It counts and weighs what you enter: diameters, spacings, end legs, the closer stirrup zones and the lap and waste allowance. Bar sizes and spacings come from a design. The result is a quantity estimate with a bar breakdown per element, not a design check and not a full bar bending schedule: anchorage, laps, starters, chairs and trimming bars are covered only by the allowance.
We do this for a living
Structural design
A structure that is sized, checked, drawn and defended, with the calculation behind every member on file.
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