D51 3m rebar — 47.7 kg per bar
A D51 3m bar weighs 47.7 kg. The 15.9 kg/m comes from the 2026.83 mm² cross-section of a 50.8 mm nominal diameter times a density of 7850 kg/m³, so 100 bars are 4770 kg and a tonne holds 20 bars.
D13 is a name, 12.7 mm is the diameter
The 13 in D13 is a label; the diameter that goes into the formula is 12.7 mm, inherited from a half inch. Feed the label into the formula and you get 1.042 kg/m, 5 % heavier than the standard value of 0.995 kg/m. The same choice is why a ribbed bar can be treated as a smooth cylinder at all: the standard sets the nominal diameter so that it reproduces the real mass.
- ⌀ 50.8 mm · 2026.83 mm²15.9 kg/m
- ⌀ 51 mm16.036 kg/m
- Bar size
- D51
- Length
- 3 m
- Nominal diameter
- 50.8 mm
- Cross-section
- 2026.83 mm²
- Weight per metre
- 15.9 kg/m
- Weight per bar
- 47.7 kg
- 100 bars
- 4770 kg
- Bars per tonne
- 20
- Lap splice
- 2.032 m · 32.309 kg
- Order weight
- 5008.5 kg
Nearby cells
Same size, other lengths
Same length, other sizes
Worth knowing
- Weight per metre (kg/m) is π/4 × nominal diameter² × 7850 ÷ 10⁶ — that is the 0.006165 factor.
- What goes into the formula is the nominal diameter, not the label: D13 means 12.7 mm.
- Total weight is weight per metre × length × count, and doubling the diameter quadruples the weight.
- An order adds lap splices, roughly 40 diameters each, and 3 to 5 % for waste.
Common questions
Q. How much does one D51 3m bar weigh?
47.7 kg — 15.9 kg/m times 3 m. Ten bars come to 477 kg and a hundred to 4770 kg.
Q. How many bars make a tonne?
20. That is 1000 divided by 47.7 kg, and 100 bars weigh 4.77 t. Ordered with 5 % waste, those 100 become 5008.5 kg.
Q. Where does 15.9 kg/m come from?
The 2026.83 mm² cross-section of a 50.8 mm nominal diameter, converted to m² and multiplied by a density of 7850 kg/m³. Using the label 51 instead would give 16.036 kg/m, which is wrong.