How is the theoretical unit weight of the rebar calculated?

It is calculated using the standard steel density of 7850 kg/m³, resulting in the formula: Unit Weight (kg/m) = (π·D²/4) · 0.00785.

Can I calculate the weight of the reinforcement steel?

Yes, by entering the optional bar length in meters, the tool will calculate the total weight based on the number of bars and their unit weight.

What standard diameters are supported?

The tool supports standard metric diameters ranging from 6 mm to 40 mm, as well as custom diameters.

What formula is used for the cross-sectional area?

The total area is calculated using A = n·π·D²/4, where n is the number of bars and D is the bar diameter.

Does this tool calculate the perimeter of the bars?

Yes, it calculates the perimeter of a single bar using the formula P = π·D.

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Rebar Area Calculator

Calculate the total cross-sectional area of reinforcing steel: A = n·π·D²/4. Choose a standard metric diameter (6–40 mm) or a custom diameter and the number of bars. Also returns the single-bar area, perimeter, theoretical unit weight (ρ=7850 kg/m³), and total weight.

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2 examples

6 bars Ø16 mm → A = 1206.4 mm²

A₁ = π·16²/4 = 201.06 mm². A = 6 × 201.06 = 1206.37 mm². Perimeter = π·16 = 50.27 mm. Unit weight = 1.578 kg/m.

{"result":"6 bars of Ø16 mm. Single-bar area = π·16²/4 = 201.06 mm². Total area = 1206.37 mm². Perimeter per bar = 50.27 mm. Unit weight = 1.58 kg/m.","metadata":{"input":{"diameterPreset":"16","count":6},"result":{"diameter":16,"count":6,"perBarArea":201.06,"totalArea":1206.37,"perimeter":50.27,"unitWeight":1.58,"unit":"mm²"}}}

4 bars Ø20 mm, 12 m → A = 1256.6 mm², W = 295.8 kg

A₁ = 314.16 mm². A = 4 × 314.16 = 1256.64 mm². Unit weight = 2.466 kg/m. Total weight = 2.466 × 12 × 4 = 118.38 kg.

{"result":"4 bars of Ø20 mm, length 12 m. Single-bar area = π·20²/4 = 314.16 mm². Total area = 1256.64 mm². Perimeter = 62.83 mm. Unit weight = 2.47 kg/m. Total weight = 118.38 kg.","metadata":{"input":{"diameterPreset":"20","count":4,"length":12},"result":{"diameter":20,"count":4,"length":12,"perBarArea":314.16,"totalArea":1256.64,"perimeter":62.83,"unitWeight":2.47,"totalWeight":118.38,"unit":"mm²"}}}

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5 options

SettingsAdjust formats, ranges, numbers, and modes.5

Bar DiameterselectOptionalCustom Diameter (mm)numberOptionalUsed only when 'Bar Diameter' = Custom.Number of BarsnumberRequiredBar Length (m, optional)numberOptionalOptional. If provided, the tool also returns the total steel weight.Decimal PlacesnumberOptional

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Rebar Area Calculator

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Examples

1. Calculating Reinforcement Area for a Concrete Beam

2. Estimating Rebar Weight for a Foundation Slab

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