How Much Concrete Do You Need for a 10x10 Slab?

Published 2026-01-26

A 10 × 10 ft concrete slab poured 4 inches thick needs about 1.23 cubic yards (33.3 cubic feet) of concrete — roughly 56 bags of 80 lb mix. At this size, ready-mix delivery is usually cheaper than bags.

A 10×10 slab is the classic shed floor, hot-tub pad, or patio square. Here is exactly how much concrete it takes and how to buy it.

The volume

cubic yards = 10 × 10 × (thickness in ÷ 12) ÷ 27

At the standard 4-inch thickness:

• Cubic feet: 100 ft² × 0.333 ft = 33.3 ft³
• Cubic yards: 33.3 ÷ 27 = 1.23 yd³

Thickness changes everything

Each 80 lb bag of concrete mix yields about 0.6 cubic feet, so bags = ft³ ÷ 0.6.

Bags vs. ready-mix

Fifty-plus bags is the tipping point. Mixing that many by hand is a full, exhausting day and risks cold joints between batches. For a 10×10 slab, most people order ready-mix delivery (usually a 1-yard minimum plus a short-load fee) — it arrives uniform and lets you place the whole pad in one pour. Bags make sense only for small footings and posts.

Don’t forget reinforcement

A slab this size typically gets #3 or #4 rebar on a 12–18 inch grid, or welded wire mesh, to control cracking. Size the grid with the rebar calculator. The Portland Cement Association has guidance on slab thickness and joint spacing worth a read before you pour.

Common mistakes

• Ordering exactly 1.23 yards. Add 5–10% for uneven subgrade and spillage — order about 1.35 yards, or you will come up short mid-pour.
• Skipping the gravel base. A compacted 4-inch gravel base under the slab drains water and prevents settling; size it with the gravel calculator.
• Pouring on frozen or dry ground. Dampen the subgrade first so it doesn’t wick water out of the mix.

For other slab sizes, we have dedicated pages like the concrete slab calculator covering 8×8 up to 40×60.