8x8 Concrete Slab Bags: 40 80-lb Bags or 0.87 yd3

Answer first: an 8x8 concrete slab at 4 inches needs about 0.87 yd3 with 10% waste, which means 40 80-lb bags, 53 60-lb bags, or 79 40-lb bags. Forty 80-lb bags are about 0.95 pallet using a 42-bag pallet check and about 3,200 lb dry mix before water, so this is still a bag-friendly small slab only if pickup payload, staging, mixer pacing, and finish timing are planned before checkout.

At a glance:

• 8x8 slab area: 64 sq ft.
• 4 inch concrete volume: about 0.79 yd3 before waste.
• With 10% waste: about 0.87 yd3.
• 80 lb bags with 10% waste: about 40 bags.
• 60 lb bags with 10% waste: about 53 60-lb bags.
• 40 lb bags with 10% waste: about 79 bags.
• Dry bagged mix to handle: about 3,200 lb dry mix.
• Pallet checkpoint: about 0.95 pallet of 80-lb bags.

An 8x8 concrete slab is 64 square feet. At 4 inches thick, plan on about 72 bags of 40 lb concrete, 48 bags of 60 lb concrete, or 36 bags of 80 lb concrete before waste. With 10% waste, that becomes about 79 bags of 40 lb, 53 bags of 60 lb, or 40 bags of 80 lb concrete.

Use the Concrete Bag Calculator when you want to adjust thickness, bag size, waste factor, and bag price. This guide gives the quick 8x8 slab answer for small patios, shed pads, equipment pads, and other square flatwork. Because an 8x8 slab can already mean dozens of bags, use the ready-mix vs bags break-even chart to compare bag labor, delivery minimums, short-load fees, and access before buying.

8x8 pickup and checkout checkpoint

An 8x8 slab is the small-pad size where bagged concrete can still be the right answer, but only if the logistics are honest. Treat the 0.87 yd3 result as a pickup, delivery, and mixer-time decision before buying 40 bags.

If you buy bags, build a Concrete Material Shopping List before checkout so pallet math, extra bags, rental tools, and delivery notes stay in one plan. If the pad needs a clean continuous finish, compare the same 0.87 yd3 in the Ready-Mix vs Bags Calculator before loading the truck.

Answer first

• Most-searched answer: buy about 40 80-lb bags for an 8x8 slab at 4 inches with 10% waste.
• Other common bag sizes: about 53 60-lb bags or 79 40-lb bags.
• Concrete volume: about 0.79 yd3 before waste or 0.87 yd3 with 10% waste.
• Handling reality: 40 80-lb bags are about 3,200 lb dry mix, or about 0.95 pallet using a 42-bag 80-lb pallet planning check.
• Next step: open the Concrete Bag Calculator to change thickness, waste, bag yield, and bag price before checkout.

Sources and checks

This page uses manufacturer bag-yield calculators for the bag counts, then adds the pickup, pallet, and ready-mix decision checks that basic quantity calculators usually skip.

If the yield printed on your bag is different from the common 0.30, 0.45, or 0.60 ft3 numbers, use the printed yield and rerun the calculator before buying.

8x8 slab decision in one screen

This is where most calculator pages stop too early. The math says bags can work. The buying decision depends on whether your vehicle, staging area, mixer, and helpers can handle one near-pallet pour without cold joints or a rushed finish.

Quick answer for an 8x8 slab

These estimates use common bag yields:

Approximate whole bags for an 8 ft by 8 ft slab:

All values are rounded up to whole bags. Check the yield printed on the bag you plan to buy, especially if you use a fast-setting or specialty mix.

Formula for an 8x8 slab

Start with slab volume:

cubic feet =
  length ft x width ft
  x thickness inches / 12

For an 8 ft by 8 ft slab at 4 inches:

8 x 8 x 4 / 12 = 21.33 ft3

Then divide by the bag yield:

bags needed = cubic feet / bag yield

Add waste before rounding up:

bags to buy =
  round up(
    bags needed x (1 + waste percentage)
  )

For simple rectangular slabs, 5% to 10% waste is a practical planning range. Use more if the base is uneven, the form depth varies, or the shape is irregular.

Example: 8x8 slab at 4 inches

Volume:

8 x 8 x 4 / 12 = 21.33 ft3

Using 40 lb bags:

21.33 / 0.30 = 71.11 bags
71.11 x 1.10 = 78.22
round up to 79 bags

Using 60 lb bags:

21.33 / 0.45 = 47.40 bags
47.40 x 1.10 = 52.14
round up to 53 bags

Using 80 lb bags:

21.33 / 0.60 = 35.55 bags
35.55 x 1.10 = 39.11
round up to 40 bags

For one-bag square-foot coverage by thickness, use the 40, 60, and 80 lb concrete bag coverage calculator. For a smaller square pad, compare the Concrete Bags for a 6x6 Slab Guide or the Concrete Bags for a 4x4 Slab Guide. For a larger square slab, see the Concrete Bags for a 10x10 Slab Guide or the Concrete Bags for a 12x12 Slab Guide.

Is bagged concrete practical for an 8x8 slab?

An 8x8 slab at 4 inches is about 0.79 cubic yards before waste:

21.33 / 27 = 0.79 yd3

With 10% waste, that is about 0.87 cubic yards. Bagged concrete can still work at this size, especially when truck access is poor or the slab is not time critical. But 40 bags of 80 lb mix is about 3,200 lb of dry material before water, so staging and mixing speed matter.

If the slab needs a continuous pour and a clean finish, compare ready-mix delivery before buying. Use the Ready-Mix vs Bags Calculator for that decision, then check total material cost in the Concrete Cost Calculator.

Pickup and mixer reality check

For CTR, the clickable answer is 40 bags. For the project, the risk is everything that number hides.

• Pickup load: 40 80-lb bags weigh about 3,200 lb before water. Check the vehicle payload rating instead of guessing from bed space.
• Pallet reality: a typical 80-lb pallet is often around 42 bags, so an 8x8 slab is close to a full pallet but still short of one cubic yard.
• Mixer pacing: 40 bags means many batches. If you are using a small mixer, plan the batch count, water source, helpers, and placement path before the first bag is opened.
• Finish timing: bagged concrete can be practical for an 8x8 pad, but a continuous finish is harder if one person is mixing and finishing at the same time.
• Ready-mix quote trigger: ask for a small-load quote if the pad is highly visible, the access is easy, or the finish quality matters more than avoiding a delivery fee.

2026 small-pad buying shortcuts

Use this quick screen before buying:

1. If the slab is 2 or 3 inches thick, bags are usually the natural path.
2. If the slab is 4 inches thick, 40 80-lb bags is still a bag-friendly project only when handling and mixer pacing are planned.
3. If the slab is 5 or 6 inches thick, compare ready-mix before checkout because the count rises to about 49 to 59 80-lb bags with waste.
4. If you need a clean patio-like finish, price the finish risk, not only the bag cost.
5. If you are close to one pallet, compare total pickup weight, delivery fee, rental mixer cost, and ready-mix short-load fee on the same screen.

Turn the 8x8 result into a checkout plan

An 8x8 slab is small enough to buy in bags, but large enough that checkout mistakes are expensive.

This is the practical difference between a bag-count page and a buying page: the estimate now tells you what to buy next and what to double-check before money moves.

40 lb vs 60 lb vs 80 lb bags

For an 8x8 slab, the best bag size depends on lifting comfort, price, and how quickly you can mix.

40 lb bags are easiest to lift, but they create the highest bag count. See the 40 lb Concrete Bag Calculator if handling weight is the limiting factor.

60 lb bags reduce the count while staying easier to move than 80 lb bags. See the 60 lb Concrete Bag Calculator for yield and coverage details.

80 lb bags usually give the lowest bag count. See the 80 lb Concrete Bag Calculator before choosing them for a larger small slab.

For thickness planning, see the Concrete Slab Thickness Guide.

Buying checklist

• Confirm the slab is actually 8 ft by 8 ft after forms are set.
• Confirm the planned thickness at several points.
• Add waste before rounding to whole bags.
• Compare total bag weight, not only price per bag.
• Plan mixing speed before the pour starts.
• Compare ready-mix if the result is dozens of bags.

FAQ

How many 80 lb bags for an 8x8 slab at 4 inches?

An 8x8 slab at 4 inches needs about 36 bags of 80 lb concrete before waste or about 40 bags with a 10% waste factor.

How many 60 lb bags for an 8x8 slab at 4 inches?

An 8x8 slab at 4 inches needs about 48 bags of 60 lb concrete before waste or about 53 bags with a 10% waste factor.

How many 40 lb bags for an 8x8 slab at 4 inches?

An 8x8 slab at 4 inches needs about 72 bags of 40 lb concrete before waste or about 79 bags with a 10% waste factor.

How many cubic yards is an 8x8 slab at 4 inches?

An 8x8 slab at 4 inches is about 0.79 cubic yards before waste. With 10% waste, it is about 0.87 cubic yards.

Should I use bags or ready-mix for an 8x8 slab?

Bagged concrete can work for an 8x8 slab when access is difficult or the pour can be paced carefully. Ready-mix may be easier if the slab needs a continuous placement, a clean finish, or fewer handling steps.

Next step

Open the Concrete Bag Calculator to enter your actual slab thickness and bag size. If the count is high, compare it with the Ready-Mix vs Bags Calculator before buying. For one-bag square-foot planning, use the 40, 60, and 80 lb concrete bag coverage chart.