TryBuildCalc12mm Rebar Weight Calculator(Rebar Weight & Quantity Calculator)
Calculate rebar weight, total length, rods, and wastage.
Calculate 12mm rebar weight, total length, rods required, and wastage for RCC work. Adjust bar diameter, length, quantity, rod length, and wastage to match your reinforcement schedule.
🕒 Last updated: August 11, 2026
Inputs
ℹ️US Imperial bar sizes (#3-#18) use their official nominal diameter, run through the same weight formula as metric bars.
Theoretical Steel
128.00 kg
Total Length: 144.00 m
Weight/m: 0.889 kg/m
Recommended Steel
(Including 5% Wastage)
134.40 kg
Extra Steel (Wastage): 6.40 kg
Rods Required: 13
Total Length: 151.20 m
Building a full cutting schedule across multiple bar marks? Bar Bending Schedule Calculator →
12mm rebar quantity estimate
12mm bars are commonly used in many RCC members, and this page starts with 12mm selected.
The calculator is pre-filled for this reinforcement use case. You can change any input and the result card, visualization, and worked example will update from the active values.
- Bar diameter fixed by default: 12 mm.
- Default setup: 12 bars x 12 m.
- Useful for slab, beam, and footing estimates.
How does the steel reinforcement calculator work?
The calculator uses standard steel weight formulas to compute rebar quantity based on diameter, length, and number of bars.
Step 1 — Calculate Weight per Meter
Where D is the diameter of the steel bar in millimeters.
Step 2 — Calculate Total Length
Step 3 — Calculate Total Weight
Step 4 — Add Wastage
Step 5 — Calculate Number of Rods
Uses the wastage-adjusted final length, not the raw total length, and always rounds up to the next whole rod since a partial rod still requires a full rod to be purchased. Standard rod length is usually 12 meters.
Calculation example for 12mm Rebar Weight Calculator
This example uses the active bar diameter, length, quantity, and wastage from this programmatic calculator page.
- Bar Diameter = 12 mm
- Length = 12 m
- Quantity = 12
- Standard Rod Length = 12 m
- Wastage = 5%
Step 1 - Calculate steel unit weight
Weight per Meter = 0.889 kg/m
Step 2 - Calculate total length and weight
Total Length = 144 m
Total Weight = 128 kg
Step 3 - Add wastage
Adjusted Length = 151.2 m
Adjusted Weight = 134.4 kg
Rods Required = 13
For this page, plan for approximately 134.4 kg of steel and 13 standard rods.
Worked Example: Rebar Calculation
Let’s calculate steel required for the following:
- Diameter = 12 mm
- Length per bar = 10 m
- Number of bars = 5
- Wastage = 5%
Step 1 — Weight per meter
Step 2 — Total Length
Step 3 — Total Weight
Step 4 — With Wastage
Final Weight = 44.4 × 1.05 = 46.62 kg
Step 5 — Rods Required
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Disclaimer: This calculator provides approximate results for planning and estimation purposes only. Actual requirements may vary based on site conditions, materials, workmanship, and local building regulations. Always consult a qualified engineer, architect, or construction professional before making final decisions.