How many bags of concrete do I need?
Bag count depends on total cubic feet and the yield per bag. Enter project area, thickness, and the yield printed on the bag. The calculator rounds up because concrete bags are bought as whole units.
60 lb vs 80 lb concrete bags
A common planning yield is about 0.45 cubic feet for a 60 lb bag and about 0.60 cubic feet for an 80 lb bag. Product yield can vary, so use the label for final ordering.
When bagged concrete makes sense
Bagged concrete is often practical for small pads, post holes, repairs, and short pours. For larger projects, compare the bag count with ready-mix delivery, labor, and minimum order rules.
Concrete bag planning table
Uses common planning yields: 0.60 cu ft per 80 lb bag and 0.45 cu ft per 60 lb bag. Verify the product label.
| Concrete volume | Cubic feet | 80 lb bags | 60 lb bags |
|---|---|---|---|
| 0.25 cu yd | 6.75 cu ft | 12 bags | 15 bags |
| 0.50 cu yd | 13.5 cu ft | 23 bags | 30 bags |
| 1.00 cu yd | 27 cu ft | 45 bags | 60 bags |
| 2.00 cu yd | 54 cu ft | 90 bags | 120 bags |
Before you calculate
- Use the yield printed on the bag you plan to buy, because 40 lb, 50 lb, 60 lb, and 80 lb products can differ.
- Measure project area and thickness before converting the volume into bags.
- Keep waste visible for over-excavation, uneven base, mixing loss, and final top-off.
Common mistakes
- Assuming every bag yields the same cubic feet.
- Buying by bag weight without checking volume yield.
- Forgetting that the final answer must round up to whole bags.
Formula
bags = ceil((area * (thickness / 12) * (1 + wastePercent / 100)) / yieldPerBag)
Assumptions
- Defaults represent 16x20 concrete slab.
- Use the yield printed on the exact bag or mix label.
- For larger pours, compare the bag count with ready-mix delivery, mixing time, and supplier minimums.
Example
Estimated concrete bags needed: 196 bags
How to calculate 16x20 concrete slab bags
- Measure the 16x20 concrete slab bags project area or volume that needs bagged material.
- Enter thickness, depth, coverage, or yield per bag from the exact product label.
- Keep waste visible for cuts, uneven base, mixing loss, spreading loss, and final top-off.
- Divide adjusted demand by the product yield and round up to whole bags.
- Confirm product instructions, water or installation requirements, delivery units, and site conditions before buying.
Before you buy materials
- Round up to full bags and compare the total bag count with ready-mix if the quantity gets large.
- Check the product label for yield, water instructions, working time, and intended use.
FAQ
How many bags do I need for 16x20 concrete slab bags?
Use area, depth or thickness, product yield per bag, and waste, then round up to the buying unit when the result is sold as whole items. In the default example, the result is 196 bags.
How do I calculate concrete bags?
Find project volume in cubic feet, add waste if needed, then divide by yield per bag. Round up to the next whole bag.
How many 80 lb bags make a cubic yard?
Using a common 0.60 cubic foot yield, one cubic yard takes about 45 bags of 80 lb concrete. Always verify the actual bag yield.
How many 60 lb bags make a cubic yard?
Using a common 0.45 cubic foot yield, one cubic yard takes about 60 bags of 60 lb concrete. Check the product label before buying.
Should I include waste when buying concrete bags?
Usually yes. A small waste buffer helps cover uneven base, over-excavation, mixing loss, and final top-off.
Related calculators
This calculator is for planning estimates only. Verify final quantities with product labels, project conditions, and a qualified professional when accuracy matters.