A 12 mm diameter and a 12 m bar length are unrelated measurements. The Whatson Steel Bar Weight Calculator gives each its own field so a schedule can be checked without confusing the two.
Diameter is always millimetres. Scheduled length follows the selected unit. A row with length 12 and feet selected means a 12 ft cut length, not a standard 12 m stock bar.
Bring a bar schedule to the calculation
Add a row for each combination of diameter and cut length. Give it a useful reference, such as a drawing mark. Quantity is the number of identical bars represented by that row.
The tool models a circular cross section and multiplies area × entered steel density × scheduled length. Its default density is 7,850 kg/m³. It reports scheduled steel first, then a separate weight with allowance.
This is a weight worksheet. It does not create hooks, bends, anchorage or lap lengths from a structural drawing.
Compare feet with metres using one row
With feet selected, enter diameter 12 mm, length 12 and quantity 10. At the default density, the checked scheduled weight is 32.473 kg. Adding 5% allowance gives 34.096 kg.
The total scheduled length is 36.576 m. These are ten 12 ft pieces.
Change the unit to metres while leaving the numerical length at 12, and you have described ten much longer pieces. The scheduled weight becomes about 106.538 kg. The tool does not automatically convert numbers when you change the unit selector.
A useful independent sense check
FF Steel’s nominal mass table lists a 12 mm bar at about 0.888 kg per metre. The circular section calculation at the default density gives about 0.887814 kg/m, which agrees after rounding.
A nominal value is not a substitute for checking delivered material, product markings and the agreed weighing basis.
What belongs in the length field?
Enter the scheduled cut length, including specified bends or laps where appropriate. Adding a lap in the row length and then adding the same physical lap again as an allowance would overstate the estimate.
The cost rate is PKR per kg and applies to weight with allowance. Transport, cutting, bending and fixing may be separate quote items.
For two directions of an already specified mesh, use the Rebar Mesh Quantity Calculator. That tool counts bars from spacing and cover; neither calculator chooses reinforcement for a building.