Steel is an alloy of iron and carbon that's created by heating iron in the presence of oxygen. Iron is a soft, malleable metal, and by adding 1.5 to 2 percent carbon, it can be transformed into steel – a material that's stronger but less malleable. Stainless steel takes it a step further by adding varying amounts of chromium to prevent rust, while cast iron is formed when the carbon content is higher than 2 percent, making it harder to shape but able to be melted and cast into moulds.

A common requirement for the shape of steel is a round bar weight calculator.
This calculation provides a quick quantity estimate for rebar weight calculations for steel weight using the unit weight of steel.


⬇️ Inputs

Bar diameter

Bar length

Number of bars

⬆️ Outputs

Bar unit weight (m/kg)

Total weight

Total weight (1)


To calculate the steel reinforcement bar tonnage, or create a steel bar weight calculator we first need to derive the 'unit weight of steel'. Once we've got this, we can then easily calculate the tonnage of steel reinforcement bar for varying diameter bars.
A common factor is used for this in most countries, we show to derive it for metric units below, using the commonly used density of steel, 7850 kg/m3.
Reinforcement steel bar length and diameter.

Which is commonly approximated to:

From here, it's easy! It's just a case of plugging in your bar diameter, and then multiplying the length and number of bars you have.

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