Start with the volume
Enter the total mixed concrete volume your project needs. If you only have dimensions, work them out in the Concrete Calculator first.
Tool Switcher: Concrete Bags
Project toolsTools
Concrete buying tool
Concrete Bag Calculator
Turn a volume you already measured into whole-bag quantities across 50, 60, and 80 lb concrete mix, with an optional cost comparison for each size.
- Three bag sizes
- US and metric units
- Optional cost compare
Concrete buying tool
Concrete Bag Calculator
Compare whole-bag counts for 50, 60, and 80 lb mixes.
Methodology
From known volume to whole bags
Add a planning allowance
The calculator starts at 0%. Increase the allowance only for your pour plan, forms, and supplier guidance.
Divide by the bag yield
Each bag size has a nominal yield. The planned volume is divided by that yield to find how many bags each size would require.
Round up to whole bags
Partial bags are rounded up, since concrete mix is sold in whole bags. Compare the counts, then verify the exact product label.
Worked example
10 ft³ with a 10% allowance
10 ft³exact volume
×1.1010% allowance
=11 ft³planned volume
From 11 ft³, the whole-bag counts are 29 × 50 lb (0.38 ft³ each), 25 × 60 lb (0.45 ft³ each), 19 × 80 lb (0.60 ft³ each). Use the label or data sheet to confirm the exact yield before buying.
Frequently asked questions
A second look at the estimate.
How do I estimate how many bags of concrete I need?
Divide your planned concrete volume by the yield of the bag size you intend to use, then round up to whole bags. This calculator does that for 50, 60, and 80 lb mixes side by side.
Should I use 50, 60, or 80 lb bags?
It depends on your project size and how much you want to handle at once. Heavier bags make fewer bags per volume; lighter bags are easier to lift. Compare the counts and cost here, then choose what fits your job.
Does the result include waste?
The exact volume does not. The planned volume applies the allowance you choose, starting at 0% so the tool does not invent a universal concrete waste rate.
Can I enter metric volume?
Yes. Metric mode uses cubic metres. Switching units preserves the same physical volume.
How is bag cost compared?
Enter a price per bag for any size. The calculator multiplies that price by the whole-bag count for that size; without a price, no cost is shown.
Sources and limitations
This tool estimates whole-bag quantities and optional cost from a known volume. It does not select mix strength, reinforcement, slab thickness, soil preparation, drainage, or structural suitability, and it does not retrieve live prices.
- Sakrete 5000 Plus product details — source for the displayed 50, 60, and 80 lb nominal yields.
- NIST volume conversion factors — reference for cubic-foot and cubic-metre conversion.
- How to measure a concrete slab — measure your project before entering a known volume.
- Concrete slab calculator — combine multiple slab sections instead of a single volume.
- Concrete bag yield guide — check the nominal yields behind each bag size.
- Concrete calculator — work out a volume from slab dimensions first.
Planning defaults for 50, 60, and 80 lb bags. Yield varies by product and mixing conditions, so the exact product label or data sheet takes priority.
Last reviewed: August 28, 2026