Concrete Mix Calculator

Calculate the exact amounts of cement, sand, gravel, and water needed for your concrete project. Supports multiple mix ratios.

Frequently Asked Questions

What is the best concrete mix ratio for a driveway?
For driveways, a 1:2:3 mix ratio (1 part cement, 2 parts sand, 3 parts gravel) is recommended. This provides the strength needed to support vehicle traffic. The concrete should have a compressive strength of at least 3,500-4,000 PSI.
How thick should my concrete slab be?
Standard residential concrete slabs are typically 4 inches thick. For driveways that will support vehicles, 5-6 inches is recommended. Patios and walkways can be 4 inches. Heavy equipment areas may require 6-8 inches with rebar reinforcement.
How long does concrete take to cure?
Concrete reaches about 70% of its strength after 7 days and 90% after 28 days. However, it continues curing and strengthening for months. Keep the surface moist during the first 7 days for optimal curing. You can walk on it after 24-48 hours and drive on it after 7 days.
What is the water-cement ratio in concrete?
The water-cement ratio is the weight of water divided by the weight of cement. A ratio of 0.45-0.50 is typical for most residential applications. Lower ratios produce stronger concrete but make it harder to work with. Too much water weakens the final product.
How do I calculate concrete volume?
Multiply length × width × depth (all in the same units). For example, a 10 ft × 10 ft slab at 4 inches deep: 10 × 10 × 0.33 = 33.3 cubic feet. Add 10% extra for waste and spillage.