How Many Bags of Concrete for a 6x6 Slab? 22 80-lb Bags

If you are asking how many bags of concrete for a 6x6 slab at 4 inches, buy 22 80-lb bags with 10% waste. The same 6 ft by 6 ft pad is about 0.49 yd3 and 1,760 lb of dry mix, or 30 60-lb bags or 44 40-lb bags, before you adjust for uneven base depth, bag yield, or local product size.

A 6x6 concrete slab is 36 square feet. At 4 inches thick, plan on about 40 bags of 40 lb concrete, 27 bags of 60 lb concrete, or 20 bags of 80 lb concrete before waste. With 10% waste, that becomes about 44 bags of 40 lb, 30 bags of 60 lb, or 22 bags of 80 lb concrete.

If you only need the per-bag square-foot answer, start with the Concrete Bag Coverage Calculator and then come back here for the full 6x6 order.

The buying answer is just as important as the math: 22 80-lb bags are about 1,760 lb of dry mix, but the job is still under one cubic yard. Bags usually make sense for a single 6x6 pad, while ready-mix is mainly worth checking when placement speed, access, helpers, or a larger combined pour changes the job.

Use the Concrete Bag Calculator when you want to adjust thickness, bag size, waste factor, and bag price. This guide gives the quick 6x6 slab answer for small pads, shed steps, equipment bases, grill pads, and other compact square flatwork. If this small slab is part of a larger order, compare the bag count with the ready-mix vs bags break-even chart before you decide whether bags still make sense.

22-bag answer and under-1-yard decision

Use this fast check before checkout:

The 22-bag order weighs about 1,760 lb, even though the concrete volume is only about 0.49 yd3. If the pad grows to 8x8, becomes thicker than 4 inches, or gets combined with another pour, rerun the quantity before loading bags.

Bag size and total dry weight

For a 6x6 slab at 4 inches with 10% waste, calculate the load from the whole bags you will buy, not from the unrounded concrete volume.

Thirty 60-lb bags weigh 1,800 lb, not the 1,760 lb shown for the 80-lb order. These totals include the mix bought for the waste allowance and exclude mixing water, passengers, tools, and other cargo. Compare the entire planned load with the vehicle's available payload before deciding how many trips to make.

Keep the material dry and stage it close to the forms before mixing. A smaller bag can reduce each lift without reducing the total weight you need to move.

Sources and checks

This page uses common bag yields for planning, not a universal product rule. Always confirm the yield printed on the bag before buying.

Concrete Estimator Hub is independent and is not affiliated with these manufacturers or ready-mix suppliers.

4-inch slab summary

• 80-lb bag order: buy about 22 80-lb bags for a 6x6 slab at 4 inches with 10% waste.
• Other common bag sizes: about 30 60-lb bags or 44 40-lb bags.
• Concrete volume: about 0.44 yd3 before waste or 0.49 yd3 with 10% waste.
• Handling weight: 22 80-lb bags means about 1,760 lb dry mix before water.
• Next step: open the Concrete Bag Calculator to adjust thickness, waste, bag yield, and price before buying.

6x6 slab decision in one screen

This is the main difference from a generic bag-count chart: the math says bags work, but the buying decision depends on whether you can move, stage, mix, and place nearly a ton of dry material before the surface starts getting away from you.

Can I pour a 6x6 slab with bags instead of ready-mix?

Usually yes. A 6x6 slab at 4 inches is only about 0.49 yd3 with 10% waste, so bags are still a normal choice if you can stage the material close to the forms and keep the mixing pace steady.

Bags usually still make sense when:

• one or two people can handle the lifting;
• the pad is a single small pour;
• truck delivery minimums would overwhelm the material cost;
• the base, forms, and tools are already ready before mixing starts.

Ready-mix becomes worth pricing when the 6x6 pad is part of a larger combined pour, when finish timing is tight, or when hand-mixing speed is the real risk.

How many 80-lb bags of concrete do I need for a 6x6 slab at 4 inches?

The direct answer is 22 80-lb bags with 10% waste.

• before waste: 20 bags
• with 10% waste: 22 bags
• dry mix to move: about 1,760 lb

If the slab is thicker than 4 inches, the bag count rises fast, so rerun the math before checkout.

Quick answer for a 6x6 slab

These estimates use common bag yields:

Approximate whole bags for a 6 ft by 6 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. The thickness rows compare quantities; they do not approve a slab design. Choose thickness for the intended use, ground conditions, and applicable requirements.

Formula for a 6x6 slab

Start with slab volume:

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

For a 6 ft by 6 ft slab at 4 inches:

6 x 6 x 4 / 12 = 12 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 square 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: 6x6 slab at 4 inches

Volume:

6 x 6 x 4 / 12 = 12 ft3

Using 40 lb bags:

12 / 0.30 = 40 bags
40 x 1.10 = 44
round up to 44 bags

Using 60 lb bags:

12 / 0.45 = 26.666666... bags before waste
12 x 1.10 / 0.45 = 29.333333... bags with waste
round up to 30 bags

Using 80 lb bags:

12 / 0.60 = 20 bags
20 x 1.10 = 22
round up to 22 bags

Keep the fractional quantity until waste is included. For a 5-inch 6x6 slab, the base volume is 15 ft3. With 60-lb bags and 10% waste, 15 x 1.10 / 0.45 = 36.666666..., so buy 37 bags. Rounding the base quantity up to 34 bags first would give 34 x 1.10 = 37.4, or 38 bags. That extra bag comes from early rounding, not a larger slab or higher waste allowance.

For one-bag square-foot coverage by thickness, use the 40, 60, and 80 lb concrete bag coverage calculator. For a smaller pad, compare the Concrete Bags for a 4x4 Slab Guide. For larger square slabs, see the Concrete Bags for an 8x8 Slab Guide and the Concrete Bags for a 10x10 Slab Guide.

Is bagged concrete practical for a 6x6 slab?

A 6x6 slab at 4 inches is about 0.44 cubic yards before waste:

12 / 27 = 0.44 yd3

With 10% waste, that is about 0.49 cubic yards. A 6x6 slab is usually still a reasonable bagged-concrete project if you can stage the bags close to the forms and mix steadily. With 80 lb bags, a 10% waste factor means buying and moving about 22 bags, or roughly 1,760 lb of dry mix before water.

If the slab must be placed very quickly or you are pouring multiple pads at the same time, compare ready-mix delivery before buying bags. 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 a 6x6 slab, the hard part is rarely the cubic-yard calculation. It is the store trip, unloading, water control, and batch timing.

• Pickup load: 22 80-lb bags is about 1,760 lb before water, so check the payload rating and make more than one trip if the vehicle is small.
• Staging: place bags near the forms before mixing so the pour area is not waiting on carrying time.
• Mixer pace: 22 large bags can be a long hand-mix job. If you rent a mixer, plan the batch order before the first bag is opened.
• Finish timing: small pads still need continuous placement. Avoid starting with only half the bags staged.
• Backup plan: if the slab is thicker than 4 inches, the base is uneven, or the pad is part of a larger project, price a small ready-mix load before buying every bag.

Turn the 6x6 result into the next decision

For a 6x6 slab, the math is usually bag-friendly. The next useful step is to turn 22 bags into a realistic store run and a clean fallback if the project stops being a simple one-pad pour.

If the result stays close to 22 80-lb bags, this is still a normal bagged concrete job. If the thickness, waste, slope, or adjacent work pushes the pad toward a larger combined pour, switch from store-run thinking into delivery and quote-review thinking before buying.

Choosing a bag size

• Use 22 80-lb bags when fewer bags matter more than lifting comfort.
• Consider 30 60-lb bags when a lighter individual bag suits your lifting limits and mixing plan; the whole order weighs about 1,800 lb.
• Use 44 40-lb bags when lifting weight is the limit and extra mixing time is acceptable.
• Buy from the same product line when possible so bag yield stays consistent.
• Add the 10% waste before rounding up to whole bags. Rounding up the base bag count first can add unnecessary bags, as the 5-inch example shows.
• Compare ready-mix only when the real constraint is speed, not volume. At 0.49 yd3, delivery minimums and short-load fees can outweigh the convenience.

40 lb vs 60 lb vs 80 lb bags

For a 6x6 slab, 40 lb bags are easier to lift but create the highest bag count. See the 40 lb Concrete Bag Calculator if handling weight is the limiting factor.

60 lb bags are a practical middle ground for a small slab. See the 60 lb Concrete Bag Calculator for yield and coverage details.

80 lb bags usually give the lowest bag count for store-bought concrete mix. See the 80 lb Concrete Bag Calculator before choosing them for a small pad.

For thickness planning, see the Concrete Slab Thickness Guide. For cubic yard planning, use the How Many Yards of Concrete Do I Need? guide.

Buying checklist

• Confirm the slab is actually 6 ft by 6 ft after forms are set.
• Confirm the planned thickness at several points.
• Add waste before rounding to whole bags.
• Use the yield printed on the actual bag.
• Stage bags close to the pour area before mixing.
• Keep bags dry before use.

FAQ

How many 80 lb bags for a 6x6 slab at 4 inches?

A 6x6 slab at 4 inches needs about 20 bags of 80 lb concrete before waste or about 22 bags with a 10% waste factor.

How many 60 lb bags for a 6x6 slab at 4 inches?

A 6x6 slab at 4 inches needs about 27 bags of 60 lb concrete before waste or about 30 bags with a 10% waste factor.

How many 40 lb bags for a 6x6 slab at 4 inches?

A 6x6 slab at 4 inches needs about 40 bags of 40 lb concrete before waste or about 44 bags with a 10% waste factor.

How many cubic yards is a 6x6 slab at 4 inches?

A 6x6 slab at 4 inches is about 0.44 cubic yards before waste. With 10% waste, it is about 0.49 cubic yards.

Is a 6x6 slab too small for ready-mix?

Usually yes, unless it is part of a larger pour. A 6x6 slab is commonly small enough for bagged concrete, but ready-mix can still make sense if access, timing, or labor is a bigger concern than the delivery minimum.

Next step

Open the Concrete Bag Calculator to enter your actual slab thickness and bag size. If you are still comparing small pad sizes, check the 4x4 slab guide and the 8x8 slab guide. For one-bag square-foot planning, use the 40, 60, and 80 lb concrete bag coverage chart.