Concrete bag calculator
Know the yards or know the dimensions. Compare the bags with ready-mix.
Calculating example…
Estimates only · see assumptions below
Your material estimate
Example estimate— yd³
- Cubic feet
- —
- Cubic meters
- —
Shape assumption. Typical mixed yields: 80 lb → 0.60 ft³; 60 lb → 0.45 ft³; 40 lb → 0.30 ft³. Read the actual bag label; special mixes differ. Each row is an alternative, not quantities to add together.
Or use premix bags
Choose one row. Whole bags rounded up after waste.
| Bag size | Typical yield | Bags | Cost |
|---|---|---|---|
| 80 lb | 0.60 ft³ | — | — |
| 60 lb | 0.45 ft³ | — | — |
| 40 lb | 0.30 ft³ | — | — |
Typical values; use the yield on the bag label. These are concrete premix bags, not plain cement.
Volume × your $/yd³. Excludes tax, delivery, short-load fees, labor and equipment. Truck capacity and minimum orders vary.
Enter positive dimensions to see a material estimate.
Estimates only. Displayed volumes use 3 decimals; calculations and bag rounding use unrounded values. Confirm supplier increments before ordering. Not construction, commercial or tax advice.
How to calculate
- Measure the shape shown above. Use the unit labels beside each field.
- Choose a waste allowance from 0–30%. The example starts at 10%.
- Read the waste-adjusted volume or choose one bag size. Add a material price if you have a quote.
- Copy or print the estimate, then verify the mix yield and order increments with your supplier.
The formula
Known volume: ft³ = yd³ × 27 (or m³ ÷ 0.028316846592). Dimensions: ft³ = length × width × thickness, all in feet. Add waste, then bags = round up(ft³ ÷ yield per bag).
Waste-adjusted volume = measured volume × (1 + waste percent ÷ 100). One cubic foot is 0.028316846592 cubic meters. Bag counts round up once; displayed volumes round to three decimals.
Worked example
1 yd³ = 27 ft³. At 0% waste: 27 ÷ 0.60 = 45 bags of 80 lb; 27 ÷ 0.45 = 60 bags of 60 lb; 27 ÷ 0.30 = 90 bags of 40 lb. At the default 10%: 50, 66 and 99 bags respectively.
Ready-mix material cost = waste-adjusted cubic yards × your price per cubic yard. A bag cost, when entered, is whole bags × price per bag. Neither cost includes delivery, tax, short-load fees, labor or equipment.
Geometry estimates material only. It does not select concrete strength, reinforcement, dimensions or a construction method.
Frequently asked questions
How many 80 lb bags make a cubic yard?
At the typical yield of 0.60 ft³, one yard (27 ft³) needs 45 bags before waste. With 10% allowance, 29.7 ÷ 0.60 = 49.5, rounded up to 50 bags. Check your bag label.
Why are bags rounded up?
You buy whole bags. This tool applies waste to the total volume first and then rounds each bag option up once. It does not round every dimension or section.
Do all 60 lb bags yield 0.45 cubic feet?
No. It is a typical value for general-purpose concrete premix. Specialty mixes and products can differ. Follow the package yield and mixing instructions.
Can I compare material prices?
Yes. Enter a ready-mix price per cubic yard and an optional price per bag size. Costs exclude delivery, tax, minimum loads, equipment and labor. Blank prices remain unquoted.
Does it tell me how many trucks to order?
It shows the waste-adjusted ready-mix volume, not a guaranteed truck count. Truck capacity, minimum order and order increments vary; request a supplier quote.
Can I convert pounds of cement directly?
No. These are mixed-concrete yields for premix bags, not dry cement volume or a custom sand-and-gravel recipe.