Bag count

Concrete Bag Calculator

Estimate concrete bags by dimensions, bag size and waste factor.

US units 10% default waste Bag and yard estimates

Concrete estimate

Enter dimensions

Printable reference

Concrete Bag Yield Chart

Use this chart for a quick sanity check before buying bagged concrete. Counts use manufacturer-style approximate yields and round up to whole bags.

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Source note: bag yields are approximate. Check the yield printed on the product you buy before checkout.

Concrete bag yield chart for 40, 50, 60 and 80 lb bags

Bag size table

40, 50, 60 and 80 lb concrete bag estimates

Use these tables after the calculator result to sanity-check common bag sizes. Counts include the same 10% planning waste used by the default calculator settings.

Bag size	Yield used	Bags per cubic yard	With 10% waste
40 lb	0.3 cu ft	90 bags	99 bags
50 lb	0.375 cu ft	72 bags	80 bags
60 lb	0.45 cu ft	60 bags	66 bags
80 lb	0.6 cu ft	45 bags	50 bags

Example slab	Base volume	40 lb	50 lb	60 lb	80 lb
4 ft x 4 ft pad, 4 in thick	5.33 cu ft	20 bags	16 bags	14 bags	10 bags
8 ft x 8 ft pad, 4 in thick	21.33 cu ft	79 bags	63 bags	53 bags	40 bags
10 ft x 10 ft slab, 4 in thick	33.33 cu ft	123 bags	98 bags	82 bags	62 bags
10 ft x 12 ft slab, 4 in thick	40 cu ft	147 bags	118 bags	98 bags	74 bags

Shopping checklist

Concrete mix bags Match the bag size to the calculator result and check the yield printed on the bag.
Mixing tub or mixer A tub works for small batches; a mixer is easier when the count gets high.
Water measure Use a bucket or marked container so each batch stays consistent.
Rebar or wire mesh Add reinforcement only where the project design calls for it.
Float, trowel and edger Have finishing tools ready before the first batch is mixed.
Gloves and eye protection Concrete mix is alkaline and should not stay on skin or in eyes.

Estimate assumptions

Estimates are for planning and ordering only.
Bag counts are rounded up to whole bags.
Ready-mix yards are rounded up to the nearest 0.25 cubic yard.
Default waste is 10%. Increase it for uneven excavation, spillage, or complex forms.
Verify structural work with a contractor, engineer, or supplier before pouring.

Bag yields used

40 lb bag0.30 cubic feet.
50 lb bag0.375 cubic feet.
60 lb bag0.45 cubic feet.
80 lb bag0.60 cubic feet.

Buying bags safely

The calculator rounds up to whole bags after adding waste. That is intentional because buying one bag short can stop the job.

Check the yield printed on the bag you are buying. If it differs from the defaults, use the result as a planning estimate and adjust before checkout.

Common next purchases

Concrete mix Rebar Tube forms Mixing tools Trowels and floats

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FAQ

How many 80 lb bags of concrete do I need?

Enter your dimensions and choose 80 lb bags. The calculator uses 0.60 cubic feet per bag and rounds up.

How many 60 lb bags equal one cubic yard?

At 0.45 cubic feet per bag, one cubic yard takes about 60 bags before waste.

Why is the bag count rounded up?

Concrete bags cannot be bought in fractions, and ordering short is usually worse than having a small amount left over.