Rebar tons needed for a building by the number of bars of each diameter

How do we turn a number of bars into weight and tons?

The calculator above works in four simple steps — the same ones engineers and traders use in Iraq:

  1. Weight per metre (kg/m) = diameter in mm × diameter in mm ÷ 162
  2. Weight of one bar (kg) = weight per metre × bar length in metres
  3. Total weight (kg) = bar weight × number of bars
  4. Tons = total weight ÷ 1000

Full example: 100 bars of 16 mm, 12 m long

Enter diameter 16, count 100 and length 12 in the calculator and you will get the same result.

Which weight does the calculator use?

The British standard BS 4449:2005 (followed by B500B rebar) allows the actual mass per metre to differ from the nominal mass by a set percentage: ±6.0% for diameters of 8 mm and below, and ±4.5% for diameters above 8 mm. So rebar that meets the standard has a lowest and a highest allowed weight, as shown in the table below.

The calculator uses the nominal weight — exactly the middle of that range — because it is the figure used in drawings and bills of quantities, and it leans neither high nor low. The actual weight on the delivery note may therefore differ slightly from the calculator's result; that is normal as long as it stays within the allowed range.

Approximate price

The price for each diameter is the average of the latest price per ton we recorded for each factory for that diameter. If a diameter has no recorded price, we use the average of all the latest rebar prices. Dollar and dinar prices are made equal with the latest stored exchange rate before averaging. Prices are approximate; for an exact price compare the factories in the price table or ask for a quote.

Rebar weight per metre and allowed range (BS 4449:2005)

Diameter (mm) Nominal (kg/m) Tolerance Lowest allowed (kg/m) Highest allowed (kg/m) Used by the calculator
8 0.395 ±6% 0.371 0.419 0.395
10 0.617 ±4.5% 0.589 0.645 0.617
12 0.889 ±4.5% 0.849 0.929 0.889
14 1.210 ±4.5% 1.156 1.264 1.210
16 1.580 ±4.5% 1.509 1.651 1.580
18 2.000 ±4.5% 1.910 2.090 2.000
20 2.469 ±4.5% 2.358 2.580 2.469
22 2.988 ±4.5% 2.854 3.122 2.988
25 3.858 ±4.5% 3.684 4.032 3.858
28 4.840 ±4.5% 4.622 5.058 4.840
32 6.321 ±4.5% 6.037 6.605 6.321

Nominal weight = d² ÷ 162. The calculator uses the nominal weight (the middle of the allowed range); the actual weight on the delivery note may be slightly different within this range.