Formula
- Use the units shown beside each field.
- Results update automatically whenever you change an input.
- Displayed values use up to four decimal places, or scientific notation for very small or large numbers. Calculations use standard floating-point arithmetic; exact integer and fraction tools identify their own precision rules.
- One planar layer, bars at both clear edges. No laps, bends, chairs, waste or reinforcement design. Density assumed 7850 kg/m³.
Example Calculation
- Slab length: 4 m
- Slab width: 3 m
- Edge cover: 0.05 m
- Maximum spacing: 0.2 m
- Bar diameter: 10 mm
A 4×3 m grid with 50 mm cover and maximum 200 mm spacing uses 16×3.9 m plus 21×2.9 m = 123.3 m.
Frequently asked questions
How do I use this calculator?
Enter slab length, slab width, edge cover, maximum spacing, bar diameter. The result updates automatically. Use Reset to restore the example values.
What method does it use?
bars in each direction=ceil(clear perpendicular dimension/spacing)+1; mass=total length × π(d/1000)²/4 × 7850.. One planar layer, bars at both clear edges. No laps, bends, chairs, waste or reinforcement design. Density assumed 7850 kg/m³.
Why might a rounded result differ?
The calculation keeps full numeric precision internally, then rounds the displayed result. Rounding intermediate steps by hand can produce a slightly different answer.
Are my inputs saved online?
No. This calculator processes your inputs in your browser. A recently used list stores only calculator names on this device, not your entered values.
Check the assumptions and units before using this result. Read about calculation methods.