TryBuildCalcSteel Reinforcement for Slab Calculator(Rebar Weight & Quantity Calculator)
Calculate rebar weight, total length, rods, and wastage.
Estimate reinforcement steel quantity for slab planning from total bar length, diameter, and wastage. 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
111.11 kg
Total Length: 180.00 m
Weight/m: 0.617 kg/m
Recommended Steel
(Including 7% Wastage)
118.89 kg
Extra Steel (Wastage): 7.78 kg
Rods Required: 17
Total Length: 192.60 m
Building a full cutting schedule across multiple bar marks? Bar Bending Schedule Calculator →
Slab reinforcement quantity estimate
This page is useful when slab bar lengths are already measured from a bar bending schedule or drawing.
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.
- Default diameter: 10 mm.
- Default setup: 15 bars x 12 m.
- Useful for slab steel ordering.
Calculation example for Steel Reinforcement for Slab Calculator
This example uses the active bar diameter, length, quantity, and wastage from this programmatic calculator page.
- Bar Diameter = 10 mm
- Length = 12 m
- Quantity = 15
- Standard Rod Length = 12 m
- Wastage = 7%
Step 1 - Calculate steel unit weight
Weight per Meter = 0.617 kg/m
Step 2 - Calculate total length and weight
Total Length = 180 m
Total Weight = 111.11 kg
Step 3 - Add wastage
Adjusted Length = 192.6 m
Adjusted Weight = 118.89 kg
Rods Required = 17
For this page, plan for approximately 118.89 kg of steel and 17 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.