How to use it
- Enter the project length in feet.
- Enter the project width in feet.
- Enter the desired concrete thickness in inches.
- Read your required cubic feet, cubic yards, and 80-lb bag count.
Running out of concrete mid-pour ruins slabs and creates cold joints. Ordering too much wastes cash. This calculator translates your project dimensions—length, width, and thickness—into exact volume and bag counts before you start mixing.
You get three critical numbers: total cubic feet, total cubic yards, and the number of standard 80-lb bags required based on a standard yield of 0.6 cubic feet per bag.
Use cubic yards if you are ordering ready-mix delivery from a truck. Use the bag count if you are mixing on-site with standard 80-lb bags. Having all three numbers allows you to price-compare bag mixing against truck delivery instantly, lock in exact material costs, and pour your slab with zero shortages or wasted materials.
Pro tips
- Add 10% to your total volume to account for subgrade variations, form deflection, and spillage.
- Always round up to the next full bag or half-yard; concrete suppliers do not sell partial units.
- Switch from 80-lb bags to ready-mix truck delivery once your project requires more than one cubic yard (45 bags).
- Do not guess slab thickness; measure form depth across multiple points to avoid under-ordering.
Real-life examples
- Pouring a 10x10 foot backyard patio slab at 4 inches thick.
- Setting up wooden forms for a new sidewalk extension or walkway.
- Estimating whether to buy bagged mix or hire a ready-mix truck for a shed foundation.
Case study
Dave needed to pour a 12x12 foot patio slab at 4 inches thick. Instead of guessing bag counts at the home center, he used this calculator to identify he needed 48 cubic feet, or 80 bags of 80-lb mix (1.78 cubic yards). Realizing that meant hauling over 6,000 lbs, he ordered two yards of ready-mix truck delivery, saving six hours of manual labor and zero wasted materials.