Concrete Bag Yield Calculator

Translate cubic feet of concrete into the number of pre-mix bags you need at 40, 60, or 80 lb per bag.

Inputs

From the concrete-volume calculator.

Result

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General calculation reads

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How to use this calculator

  • Enter the volume of concrete you need in cubic feet.
  • Pick a bag size — 80 lb is the most economical for medium jobs, 60 lb easier to lift.
  • Read the bag count and total weight.

About this calculator

Pre-mix bags are convenient for small repairs but get expensive fast — about 1 yd³ per ~45 bags of 80-lb mix. Use bags for posts, repairs, and small pads under ~1 yd³; switch to a ready-mix truck above that. The yields here come from manufacturer data: a 40-lb bag yields ~0.30 ft³, 60-lb ~0.45 ft³, 80-lb ~0.60 ft³.

Frequently asked

When should I switch from bags to ready-mix?+
At about 1 cubic yard (around 45 80-lb bags). Below that, bags are usually cheaper than the short-load surcharge a ready-mix plant charges.
Why are the per-bag yields different?+
Pre-mix density is roughly the same regardless of bag size, so a 40 lb bag yields about half the volume of an 80 lb bag.
Are these yields the same brand-to-brand?+
Almost. Quikrete, Sakrete, and Sika all publish 0.60 ft³ per 80 lb bag of standard concrete mix; high-strength and fast-set mixes can vary slightly.
Do I need to add water weight to my total?+
No — the bag-weight number is just for hauling. Each 80 lb bag takes about 6 pints of water once mixed.
What if my project is fence-post setting?+
For fence posts, fast-set concrete (e.g. Quikrete Fast-Set) is much easier — no mixing required. Yields are similar.

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