Concrete Calculator
Calculate concrete volume for your slab in cubic feet, cubic yards, and cubic meters. Get the number of 40lb, 60lb, and 80lb bags of concrete to buy plus a cost estimate. 100% browser-based, no signup.
Always order 5–10% extra for spillage and uneven subgrade. Bag counts assume standard premix yields; specialty blends may vary.
Slab Volume
Enter length, width, and thickness (in inches or feet) and instantly get the volume in cubic feet, cubic yards (÷27), and cubic meters (×0.0283168).
Bag Calculator
Know exactly how many bags of premix concrete to buy. The calculator returns counts for 40lb (yields 0.30 cu ft), 60lb (0.45), and 80lb (0.60) bags, rounded up so you never run short.
Cost Estimate
Enter the price per cubic yard of ready-mix concrete and get an instant cost estimate for your project, ready to compare against bagged premix pricing.
100% Private
All calculations run in your browser. Nothing is uploaded, there is no signup, and there is no daily limit. Use it on site from your phone.
How much concrete do I need for a 10×10 slab that is 4 inches thick?
A 10×10 slab at 4 inches thick is 100 sq ft × 0.333 ft = 33.3 cu ft, which is about 1.23 cubic yards (÷27) or roughly 56 sixty-pound bags of premix concrete. Always order 5–10% extra for spillage and uneven subgrade.
How is the volume calculated?
For a rectangular slab the formula is V = length × width × thickness. The thickness in inches is converted to feet by dividing by 12. Cubic yards are obtained by dividing cubic feet by 27 (since 1 yard³ = 27 ft³). Cubic meters = cu ft × 0.0283168.
How many cubic feet does a bag of concrete yield?
A 40 lb bag yields about 0.30 cu ft, a 60 lb bag about 0.45 cu ft, and an 80 lb bag about 0.60 cu ft of cured concrete. These are industry-standard values for standard premix; specialty blends may differ slightly.
Should I order extra concrete?
Yes — order 5 to 10 percent more than the calculator shows to cover spillage, over-excavation, and an uneven subgrade. Running short means a cold joint and a second delivery fee; a small surplus is cheap insurance.
Is the calculator free to use?
Yes — 100% free, no signup, and no daily limit. It runs entirely in your browser so you can use it on site, on your phone, with or without a signal.
Ready to use the Concrete Calculator?
Free, no signup, no watermark. 100% browser-based. Your data never leaves your device.
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