SPECIFICATION: Backyard Patio, Small Shed Base, Hot Tub Pad

10×10 Concrete Slab Calculator (Bags & Yards)

A 10×10 slab at standard 4-inch thickness covers 100 square feet and requires 1.23 net cubic yards (approximately 1.36 cubic yards with 10% waste buffer). At 61 bags (80 lb), this is a classic DIY weekend pour manageable with a rented portable electric mixer.

SLAB DIMENSIONS100 SQ FT
THICKNESS (INCHES)4" Depth
+10%
DIY Retail Bag Weight:
Live Structural Cross-Section
10' × 10' Slab (4" Depth)
Structural cross-section of 10' x 10' concrete slab4" CONCRETE4" #57 STONE#4 REBAR @ 18" O.C.10 MIL VAPOR BARRIERCOMPACTED SUBGRADESPAN: 10 FT × 10 FT
Net Volume:1.23 cu yds
Order (+Waste):1.35 cu yds
Base Prep:4" Crushed Base
Reinforcement:#4 @ 18" O.C.
Yield Comparison (10' × 10')
DIY RETAIL STORE PICKUP
61 Bags
80 lb bags (~2 full pallets)
Dry Weight:4,880 lbs
Est. Bag Cost:$397
COMMERCIAL READY-MIX
1.35 cu yds
1 mixer truck (3500 PSI)
Delivery Scale:Short-Load Fee (<3 yds)
Est. Ready-Mix:$342

Frequently Asked Questions: 10×10 Concrete Slab Calculator (Bags & Yards)

How many 80lb bags of concrete for a 10x10 slab at 4 inches?

You will need approximately 61 bags of 80 lb concrete (or 82 bags of 60 lb concrete) including a 10% contingency buffer for uneven excavation and spillage.

Can I mix a 10x10 concrete slab by hand?

While possible, hand-mixing 61 bags in a wheelbarrow takes 4-6 hours and risks cold joints where early batches cure before later ones are poured. Renting a towable mixer ($50-$80/day) is strongly recommended.

Does a 10x10 slab need rebar?

Yes. A grid of #4 rebar spaced at 18 inches on-center elevated on 2-inch plastic chairs prevents tension cracking and keeps slabs level during winter freeze-thaw cycles.