How to calculate concrete?

To calculate concrete, multiply length × width × thickness to get volume in cubic feet, then divide by 27 to convert to cubic yards. For example, a 10ft × 10ft × 4in (0.33ft) slab needs: 10 × 10 × 0.33 = 33 cubic feet ÷ 27 = 1.22 cubic yards. Our concrete calculator handles all conversions automatically and shows results in yards, bags, and cost.

How to calculate yards of concrete?

Calculating yards of concrete involves finding the volume in cubic feet first, then dividing by 27 (since 1 cubic yard = 27 cubic feet). The formula is: (Length in feet × Width in feet × Thickness in feet) ÷ 27 = Cubic Yards. For a typical 4-inch thick driveway that's 20ft × 30ft: (20 × 30 × 0.33) ÷ 27 = 7.33 cubic yards. Always add 10% for waste, making it 8.06 yards.

How many bags of concrete do I need calculator?

Our concrete bag calculator instantly converts cubic yards to bags. One cubic yard typically requires: 45 bags of 80lb concrete, 60 bags of 60lb concrete, or 90 bags of 40lb concrete. For example, a 2 cubic yard project needs 90 bags of 80lb concrete. The calculator shows all three bag sizes simultaneously, helping you choose based on price and handling preference.

How to calculate concrete for a slab?

To calculate concrete for a slab, measure length and width in feet, and thickness in inches. Convert thickness to feet (divide by 12), then multiply all three dimensions. A 12ft × 16ft patio with 4-inch thickness needs: 12 × 16 × 0.33 = 63.36 cubic feet or 2.35 cubic yards. Our concrete slab calculator simplifies this process - just enter dimensions in any unit and instantly see yards, bags needed, weight, and estimated cost.

How much concrete do I need calculator - for different shapes?

Our concrete calculator handles multiple shapes beyond basic slabs. For cylinders/columns: π × radius² × height. For footings: length × width × depth. For steps: (rise × run × width × number of steps). For curbs: complex cross-sectional area × length. Each shape has its own dedicated calculator with visual preview, ensuring accurate calculations for any project type.

How to calculate concrete yards to bags conversion?

Converting concrete yards to bags depends on bag size. Standard conversions: 1 cubic yard = 45 bags (80lb), 60 bags (60lb), or 90 bags (40lb). For partial yards, multiply accordingly. Example: 0.5 yards needs 23 bags of 80lb concrete. Our calculator automatically shows all three bag sizes with exact counts, including fractional bags.

How to calculate concrete weight and cost?

Concrete typically weighs 150 pounds per cubic foot or 4,050 pounds per cubic yard. To calculate cost, multiply cubic yards by price per yard (usually £120-£160). Our concrete cost calculator shows both weight (important for delivery planning) and cost estimation with customizable pricing. You can adjust the price per yard based on local rates and instantly see total project cost.

What makes this the best concrete calculator?

Our concrete calculator stands out with unique features: calculates 5 different shapes (slab, cylinder, steps, footing, curb), shows instant bag requirements for all sizes, generates professional PDF reports for permits and contractors, includes customizable waste factor (5-15%), supports both imperial and metric units, and provides real-time cost estimation. Unlike basic calculators, we offer a complete solution from planning to purchasing.

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Terms of Service

Last updated: 15 July 2026

1. Acceptance of Terms

By accessing and using Concrete Calculator UK (concretecalculator.uk), you agree to be bound by these Terms of Service. If you do not agree, please do not use the site.

2. Description of Service

We provide free online concrete calculators for estimating volumes, quantities, and approximate costs. Our tools are designed for general guidance and planning purposes.

3. Disclaimer of Accuracy

All calculations are estimates only. Results should not be used as the sole basis for purchasing decisions or construction work. Actual concrete requirements may vary due to:

Ground conditions and sub-base preparation
Wastage, spillage, and over-excavation
Variations in concrete mix specifications
Site-specific factors and tolerances

Always consult a qualified professional for critical construction projects.

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