Concrete Bag Calculator
Find how many bags of complete concrete mix you need. These mixes already contain cement and aggregate; cement-only bags need a different calculation.
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Stored on this device only. Anyone with a shared link can read its estimates. Don’t put addresses or personal details in labels. Concrete, concrete bags, gravel and blockwork share this list. Compatible demand is combined before purchasing rounding. Up to 20 items; long projects may need printing instead of sharing.
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Storage, sharing & privacy
No dimension inputs or project payloads are sent to analytics. This preview has no ads, analytics or account system. Shared estimates are encoded in the URL fragment, not the page path. Projects are stored in this browser’s local database. Browser clearing, eviction or device loss can remove them; keep a shared link or printed copy of important estimates. Clear project removes database estimates; retained older storage may still appear for explicit recovery.
Incoming shared projects open for review. They never replace a saved project automatically. Save an individual shared estimate to add it to your local project.
How many bags of concrete do I need?
Combine net shape volumes, add your chosen waste once, then divide by the exact product’s mixed yield. Round the combined purchase upward to whole bags. For a volume that already includes waste, divide that supply volume directly by yield.
Bags = ⌈supply volume ÷ mixed yield per bag⌉
Worked example: 10 × 10 ft slab
At 4 in depth, net volume is 33⅓ ft³. A 10% allowance gives 36⅔ ft³. Divide by the 80 lb QUIKRETE 1101 yield of 0.60 ft³: round upward to 62 bags. Calculations retain full precision before purchasing rounding.
All existing shape assumptions appear with your measurements. Subtract a post only in Post Hole mode. Avoid overlapping areas; solid columns are not hollow tubes, and the steps estimate excludes a landing or hollow core.
Product yields and bags per cubic yard
One cubic yard = 27 ft³. These whole-bag examples include 0% waste; products are not interchangeable by weight or suitability.
| Product | Approximate mixed yield | Bags / yd³ |
|---|---|---|
| QUIKRETE 1101 · 80 lb | 0.6 ft³ | 45 |
| QUIKRETE 1101 · 60 lb | 0.45 ft³ | 60 |
| QUIKRETE 1101 · 50 lb | 0.375 ft³ | 72 |
| QUIKRETE 1101 · 40 lb | 0.3 ft³ | 90 |
| Blue Circle Multi-Purpose Concrete · 20 kg | 0.01 m³ | 77 |
Practical limits and ordering guidance
Bag yields are approximate. Check the exact product label and local project specifications before ordering. Custom products need their own mixed yield.
This tool estimates complete bagged concrete quantities. It does not calculate cement, sand and aggregate recipes, assess structural design or establish code compliance.