Calculate how much concrete you need in cubic yards and bags for slabs, driveways, sidewalks, and fence posts.
Don't know your area? Measure it with LotSite for free →
Cubic yards and 80-lb bags needed for a 4-inch slab.
| Area | Cu Yards | 80-lb Bags | Bag Cost | Ready-Mix |
|---|---|---|---|---|
| 50 sq ft | 0.6 | 28 | $196 | $93 |
| 100 sq ft | 1.2 | 56 | $392 | $185 |
| 200 sq ft | 2.5 | 112 | $784 | $370 |
| 400 sq ft | 4.9 | 223 | $1,561 | $741 |
| 600 sq ft | 7.4 | 334 | $2,338 | $1,111 |
| 1,000 sq ft | 12.3 | 556 | $3,892 | $1,852 |
The most important step in any concrete project is accurate measurement. Ordering too little means a cold joint (where fresh concrete meets hardened concrete), which creates a structural weakness. Ordering too much wastes money. Add 5 to 10 percent to your calculated volume for waste and spillage.
For small projects (under 1 cubic yard), bagged concrete mix is practical — just add water and mix in a wheelbarrow or mixer. For anything larger, order ready-mix delivery. Most ready-mix companies have a minimum order of 1 cubic yard and charge short-load fees for small deliveries.
Use LotSite to measure your project area precisely. View your driveway, patio, or walkway area on satellite imagery and get exact square footage — especially useful for irregularly shaped areas.
Enter your address and measure the area for your concrete pour on satellite imagery.
Also check out our paver calculator and gravel calculator