Concrete Slab Calculator

Estimate exactly how much concrete you need for a slab, pad, or footing — get volume, bag counts, weight, and cost in seconds.

Project Details

Unit System

Pricing Region

Length

Width

Thickness

Quantity

slabs

Waste Factor

0%Exact 5%Precise 10%Recommended 15%Uneven

Results

Enter your dimensions to see results.

Pro Tips

Measure to the nearest inch (or centimeter) — small errors add up over large pours.
Order about 10% extra to cover spillage, uneven subgrade, and over-excavation. Running short mid-pour is costly.
Residential patios and sidewalks are typically 4" thick; driveways carrying vehicles should be 5–6".
For projects over 1 cubic yard, ready-mix delivery is usually cheaper and more consistent than bags.

Calculations are estimates only. Bag yields assume standard pre-mix (80 lb ≈ 0.60 ft³, 60 lb ≈ 0.45 ft³, 50 lb ≈ 0.375 ft³, 40 lb ≈ 0.30 ft³) and wet weight of ~150 lb/ft³. Costs use 2026 national-average baselines (bagged ~$5.50–$7.50 per 80 lb bag, ready-mix ~$135–$175 per cubic yard, installation ~$6–$12 per sq ft) adjusted by the selected pricing region — labor varies more by region than materials. Ready-mix delivery and short-load/minimum-order fees ($60–$320 per truck) are additional, and decorative finishes, higher-PSI mixes, or difficult site access push costs higher. Always confirm with local suppliers.