Concrete bag calculator
Find how many whole bags to buy from your concrete volume and the finished yield printed on your product.
- Bags to buy
- —
- Volume including extra
- —
- Volume from purchased bags
- —
Enter the concrete volume and the finished yield per bag.
If your volume already includes an allowance, leave extra at 0%. The example yield is illustrative; use the finished yield on your product label, not the bag weight.
In Pro², calculate volume from slab or post-hole dimensions, then plan your concrete supply.
View Pro² on the App StoreBrowser calculation is free. Pro² has limited free use; unlimited calculations and PNG/PDF export require paid access.
How the numbers fit together
Round up to whole bags so the purchased volume covers the required volume.
- V: m³ · Y: L · p: %
- N = ⌈V × (1 + p / 100) / (Y / 1000)⌉
- V: yd³ · Y: ft³ · p: %
- N = ⌈V × (1 + p / 100) / (Y / 27)⌉
A worked example
If your volume already includes an allowance, leave extra at 0%. The example yield is illustrative; use the finished yield on your product label, not the bag weight.
- Known concrete volume
- 0.37 m³
- Finished yield per bag
- 18 L
- Extra allowance
- 0%
- Bags to buy
- ⌈0.37 / 0.018⌉ = 21
- Volume from purchased bags
- 21 × 0.018 = 0.378 m³
From volume to delivery
Ready-mixed concrete planning uses the required volume and the truck capacity you enter. For bagged concrete mix, use the finished yield per bag; bag mass alone does not determine it. Round bags and loads up to whole units. Optional cost uses your entered price per volume or per bag.
Use the inside dimensions of the formwork or the actual excavation. Keep intersections from being counted twice. The app estimates the volume you describe; it cannot infer irregular ground, hidden voids or a structural specification.