Concrete planning tool
Choose a 40, 60, or 80 lb bag size and estimate a whole-bag quantity for a small rectangular pad or repair. Quantities use sourced approximate mixed yields and always round upward.
Whole-bag calculator
Select the actual bag size; the result uses sourced approximate yield and rounds up.
Plan responsibly
This project may be subject to local permit, zoning, site, or structural requirements.
Local requirements control: Model-code references do not confirm the code edition, amendments, zoning rules, permit requirements, or site criteria adopted for your project.
Bag count is not compliance: A bag estimate does not verify structural adequacy, mixture quality, reinforcement, subgrade, placement, consolidation, or curing.
Concrete performance, not bag count: The cited IRC topic concerns concrete performance. It does not establish a universal bag yield, bag-count formula, or waste allowance.
Source: ICC Digital Codes: 2021 IRC Section R402.2 · Reviewed 2026-08-24
Local requirements may differ. A model-code reference does not confirm the code edition, amendments, zoning rules, or permit requirements adopted where the project is located.
2021 IRC, Section R402.2: Concrete performance, not bag count. Source: ICC Digital Codes: 2021 IRC Section R402.2. Reviewed 2026-08-24.
Local requirements may differ. Verify the adopted code, amendments, zoning rules, and permit requirements with the local authority.
Methodology
Plan Otter calculates rectangular volume in cubic feet, applies the selected waste allowance, divides by the cited approximate yield for the chosen bag size, and ceilings the result to a whole bag.
The result uses only the selected 40, 60, or 80 lb size. Changing bag size changes both approximate yield and required count.
Product data gives approximate mixed yield. Mixing water, handling, placement, site variation, and product differences can affect actual coverage; verify the specific bag label before purchase.
A high count means substantial lifting, staged mixing, placement time, and consistency risk. Compare ready-mix delivery for larger or time-sensitive pours.
Worked examples
At 4 inches thick with 10% waste, the result is 11 80 lb bags.
At 3 inches thick with 5% waste, the result is 6 60 lb bags.
Common questions
The cited product data lists approximate yields of 0.30 ft³ for 40 lb, 0.45 ft³ for 60 lb, and 0.60 ft³ for 80 lb concrete-mix bags. Verify the product you purchase.
Concrete mix is purchased in whole bags. Rounding down would provide less than the calculated adjusted volume, so the count is always ceiled.
This calculator models one selected bag size at a time so the result remains clear and reproducible. Recalculate with another size to compare counts.
Yes. The selected waste percentage is applied to volume before the calculator divides by bag yield.
No. Local price and inventory are not inferred. Multiply the result by a current retailer or supplier quote separately.
Sources
Last reviewed: 2026-08-22
Related tools
