10x12 Concrete Slab Calculator: 1.63 yd3, 74 Bags, Cost
Answer first: a 10x12 slab at 4 in needs 1.63 yd3 with waste, about 74 80-lb bags, or $960-$2,160 installed before base, reinforcement, access, and cleanup.
Answer first: a 10 ft x 12 ft concrete slab at 4 inches thick needs about 1.63 yd3 of concrete with 10% waste, or roughly 74 common 80-lb bags. As an installed-cost screen, the same 120 sq ft slab often needs a local quote check around $960-$2,160 at $8-$18 per sq ft before base prep, reinforcement, access, cleanup, permits, finish, or minimum-load fees change the number.
Use the Concrete Slab Calculator for exact dimensions, the Concrete Cost Calculator for local material assumptions, and the Concrete Quote Reviewer when a contractor bid says "10x12 slab" but does not spell out the base, thickness, reinforcement, finish, and delivery scope. If you only need the bag-count answer, use How Many Bags of Concrete for a 10x12 Slab?.
10x12 slab answer in one screen
This is the quick calculator-style answer for the query
10x12 concrete slab calculator.
| 10x12 slab planning item | 4 in answer |
|---|---|
| Finished area | 120 sq ft |
| Concrete before waste | 1.48 yd3 |
| Concrete with 10% waste | 1.63 yd3 |
| 80-lb bags with waste | 74 bags |
| 60-lb bags with waste | 98 bags |
| Ready-mix material check | about $393.95 at $165/yd3 + $125 delivery |
| Installed cost screen | $960-$2,160 at $8-$18/sq ft |
| Buying fork | bags, small ready-mix load, or installed contractor quote |
The useful decision is not only the yardage. A 10x12 slab is small enough that ready-mix may trigger a short-load or minimum-order fee, but large enough that 74 heavy bags can create mixer fatigue, cold joints, and pickup payload issues.
Thickness, bags, and cost table
These planning numbers use 10% waste, common bag yields of 0.60 ft3 for 80-lb bags, 0.45 ft3 for 60-lb bags, and a ready-mix material check of $165 per yd3 plus a $125 delivery or small-load line.
| Thickness | Concrete with waste | 80-lb bags | 60-lb bags | Ready-mix material check | Installed screen |
|---|---|---|---|---|---|
| 4 in | 1.63 yd3 | 74 | 98 | $393.95 | $960-$2,160 |
| 5 in | 2.04 yd3 | 92 | 123 | $461.60 | quote scope decides |
| 6 in | 2.44 yd3 | 110 | 147 | $527.60 | quote scope decides |
The installed range is a sanity check, not a local bid. A simple shed pad, patio base, hot-tub pad, or small shop slab can price differently once excavation, gravel, reinforcement, drainage, access, and finish are written.
Formula for a 10x12 concrete slab
cubic yards = length ft x width ft x thickness in / 12 / 27
order quantity = cubic yards x 1.10
At 4 inches:
10 x 12 x 4 / 12 / 27 = 1.48 yd3 before waste
1.48 x 1.10 = 1.63 yd3 with 10% waste
To convert the same result into 80-lb bags:
80-lb bags = 1.63 yd3 x 27 ft3 per yd3 / 0.60 ft3 per bag
80-lb bags = 73.35, round up to 74 bags
For a shed-specific version of this decision, see the Concrete Shed Base Calculator and the Shed Base Concrete Mix Calculator Guide.
Bags vs ready-mix for a 10x12 slab
A 10x12 slab sits near the crossover point where the cheapest material line is not always the cheapest work path.
| Buying path | When it may fit | What can make it expensive |
|---|---|---|
| 80-lb bags | Tight access, no truck access, flexible timing, small DIY crew. | 74 bags weigh about 5,920 lb dry before water, plus mixer rental and labor. |
| Store delivery | You want bags but not repeated pickup trips. | Delivery fees, pallet handling, storage, rain protection, and returns. |
| Ready-mix | Better placement pace and fewer batches. | Minimum billable yards, short-load fee, chute reach, wait time, and tax. |
| Installed quote | Base prep, forms, finish, warranty, or code matters. | Missing scope lines can hide excavation, gravel, reinforcement, cleanup, and access. |
If the slab is behind a house, check the Concrete Wheelbarrow Distance Calculator before assuming the truck can reach the forms. If the quote lists ready-mix separately, normalize the delivered total with the Concrete Ready-Mix Near Me Quote Script.
Quote scope for a 10x12 slab
Two bids can both say "10x12 concrete slab" and still include different work. Ask for the scope in writing before comparing totals.
| Quote line | What to confirm |
|---|---|
| Layout | Finished 10 ft x 12 ft size, edge detail, and whether forms are included. |
| Excavation | Cut depth, spoils handling, soft-spot repair, and grading. |
| Gravel base | Depth, aggregate type, compaction, and fabric if needed. |
| Thickness | 4 in, 5 in, 6 in, or engineered detail for the actual use. |
| Reinforcement | Wire mesh, rebar, fiber, dowels, chairs, or no reinforcement. |
| Concrete | Yards, mix strength, air entrainment, slump, delivery, and waste. |
| Finish and joints | Broom or trowel finish, joint spacing, curing, and edge work. |
| Access and cleanup | Chute, buggy, pump, wheelbarrow, washout, leftover concrete, and form removal. |
Use the Concrete Scope of Work Checklist to compare bids line by line. If the slab will carry a vehicle, hot tub, shed, or shop equipment, also check thickness, base, and reinforcement with a qualified local professional before ordering.
Sources and checks
This page uses planning math and quote-screening ranges. Product yield, local ready-mix pricing, site access, and installed labor should be confirmed before buying concrete.
| Check | Source | How it is used |
|---|---|---|
| Slab volume formula | Concrete Slab Calculator | Converts 10 ft x 12 ft x thickness into cubic yards and waste. |
| Bag yield cross-check | QUIKRETE calculator and Sakrete concrete calculators | Cross-checks common 40/60/80-lb bag yield assumptions. |
| Installed flatwork cost context | ConcreteNetwork concrete driveway cost guide and Homewyse concrete slab estimator | Keeps installed screens separate from material-only concrete math. |
| Ready-mix practice context | NRMCA CIP guidance | Keeps delivery, placement, curing, yield, water, and jobsite coordination in the quote review. |
FAQ
How much concrete do I need for a 10x12 slab?
At 4 inches thick, plan about 1.48 yd3 before waste or 1.63 yd3 with 10% waste. At 5 inches, plan about 2.04 yd3 with waste. At 6 inches, plan about 2.44 yd3 with waste.
How many 80-lb bags for a 10x12 slab?
At 4 inches thick with 10% waste, buy about 74 common 80-lb bags. At 5 inches, buy about 92 bags. At 6 inches, buy about 110 bags.
How much does a 10x12 concrete slab cost?
As a planning screen, the concrete-only ready-mix check at 4 inches is about $393.95 using $165 per yd3 plus a $125 delivery line. Installed cost may screen around $960-$2,160 at $8-$18 per sq ft before local scope changes the quote.
Is a 10x12 slab too big for bags?
It can be poured with bags, but 74 80-lb bags is heavy work. Compare store delivery, mixer rental, labor, finish timing, and ready-mix minimums before checkout.
Should a 10x12 slab be 4 inches or 6 inches thick?
Four inches is a common planning starting point for light slabs. Vehicle loads, hot tubs, shed weight, shop equipment, soil, frost, base prep, and local rules can require a thicker or engineered slab.
Next step
Run the exact dimensions in the Concrete Slab Calculator, compare bagged and ready-mix totals in the Ready-Mix vs Bags Calculator, then review the written bid in the Concrete Quote Reviewer.
Quote planning next step
Turn this guide into a concrete buying check
Run the matching calculator, then compare ready-mix, bagged concrete, delivery fees, access needs, and quote gaps before you buy materials or approve a contractor number.