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Free estimator · Updated 2026

Concrete Bag Calculator: How Many Bags Do You Need for Any Project?

Enter your slab dimensions or cubic footage below and get the exact bag count for 40, 50, 60, and 80 lb bags in under 10 seconds.

Bags of Concrete Per Cubic Yard

Bag Size	Yield	Bags / yd3	Price
40 lb bag	0.30 ft3	90 bags	~$4.50/bag
50 lb bag	0.375 ft3	72 bags	~$5.50/bag
60 lb bag	0.45 ft3	60 bags	~$6.50/bag
80 lb bag	0.60 ft3	45 bags	~$7.50/bag

1 yd3 = 27 ft3. Rule of thumb: 45 x 80 lb bags = 1 cubic yard.

Concrete bag calculator

Project inputs

LengthftWidthftThickness

Bag Size FocusWaste Factor

Results

Bags needed

10% waste included

Volume

36.67 ft3

1.36 yd3 with waste

Focused Bag

80 lb bags

Bag Size	Bags	Cost	Notes
40 lb	123	$554	1 pallet + 43 bags
50 lb	98	$539	1 pallet + 38 bags
60 lb	82	$533	1 pallet + 26 bags
80 lb	62	$465	Best value
80 lb Maximizer	46	$436	33% more yield

Compare ready-mix: This is past the usual bagged-concrete comfort zone. Ready-mix delivery is likely faster and may be cheaper.

Ready-mix comparison: $244 concrete + $140 short-load fee = $384. Ready-mix saves $81 vs. 80 lb bags.

Short-load warning: ready-mix suppliers commonly add fees below 3-4 yd3.

Brand reference

Quikrete & Sakrete Bag Sizes

Prices are national planning averages for May 2026. Local store pricing varies.

Quikrete Products

Product	Size	SKU	Yield	Price	Best For
Quikrete Concrete Mix	40 lb	110140	0.30 ft3	~$4.78	Small repairs, tight spaces
Quikrete Concrete Mix	60 lb	110160	0.45 ft3	~$5.98	Medium patches, small slabs
Quikrete Concrete Mix	80 lb	110180	0.60 ft3	~$7.48	Best value - most projects
Quikrete 5000	80 lb	100700	0.60 ft3	~$8.28	Structural, 5,000 PSI
Quikrete Fast-Setting	50 lb	100450	0.375 ft3	~$7.98	Post holes, no mixing needed
Quikrete Fast-Setting	80 lb	100480	0.60 ft3	~$10.48	Larger post holes
Quikrete Crack-Resistant	80 lb	110280	0.60 ft3	~$8.98	Driveways, freeze-thaw climates
Quikrete Countertop Mix	80 lb	110380	0.60 ft3	~$18.98	Countertops, high-finish

Sakrete Products

Product	Size	SKU	Yield	Price	Best For
Sakrete Concrete Mix	40 lb	65200920	0.30 ft3	~$4.48	Small repairs
Sakrete Concrete Mix	60 lb	65200930	0.45 ft3	~$5.78	Medium projects
Sakrete Concrete Mix	80 lb	65200940	0.60 ft3	~$7.28	Best value
Sakrete 5000 Plus	80 lb	65200960	0.60 ft3	~$8.48	High-strength, 5,000 PSI
Sakrete Fast-Setting	50 lb	65306217	0.375 ft3	~$7.68	Post holes
Sakrete Maximizer	80 lb	65306218	0.80 ft3	~$9.48	33% more yield - large slabs

Quikrete vs Sakrete: Which Should You Buy?

Quikrete has a wider Home Depot product line and Quikrete 5000 is common for structural work. Sakrete is often slightly cheaper at Lowe's, and Sakrete Maximizer gives 0.80 ft3 per 80 lb bag. For most homeowners, both brands are equivalent; buy whichever is cheaper and available locally.

How Many Bags of Concrete Do You Need?

All values include 10% waste and use 80 lb bags with 0.60 ft3 yield.

Project	Dimensions	Thickness	Volume	80 lb Bags	60 lb Bags	Cost (80 lb)
Fence post hole	10 in dia x 3 ft deep	-	1.5 ft3	3 bags	4 bags	$22
Deck post hole	12 in dia x 4 ft deep	-	3.4 ft3	6 bags	8 bags	$45
Mailbox post	8 in dia x 2 ft deep	-	0.7 ft3	2 bags	2 bags	$15
10x10 patio	10x10 ft	4 in	36.7 ft3	62 bags	82 bags	$465
12x12 patio	12x12 ft	4 in	52.8 ft3	88 bags	118 bags	$660
4x20 sidewalk	4x20 ft	4 in	29.3 ft3	49 bags	66 bags	$368
Shed base 10x12	10x12 ft	4 in	44.0 ft3	74 bags	98 bags	$555
20x20 patio	20x20 ft	4 in	146.7 ft3	245 bags	327 bags	$1,838
Step repair	3 ft wide x 1 step	4 in tread	4.4 ft3	8 bags	10 bags	$60
Crack fill	1 in wide x 1 in deep	per 10 ft	0.07 ft3	1 bag	1 bag	$7.50
Sonotube 10 x 4 ft	10 in dia x 4 ft	-	2.5 ft3	5 bags	6 bags	$38
Sonotube 12 x 4 ft	12 in dia x 4 ft	-	3.5 ft3	6 bags	8 bags	$45

20x20 patio crossover: at 245 bags, ready-mix delivery can save roughly $950 versus bagged concrete. This is well past the usual switch point.

Decision point

Bags vs. Ready-Mix: Exactly When to Switch

Use bags: under 1 yd3, or fewer than about 45 x 80 lb bags.

Borderline: 1.0-1.5 yd3. Compare your short-load fee.

Use ready-mix: over 1.5 yd3, or more than about 68 x 80 lb bags.

For current delivered rates, compare ready-mix concrete prices.

Volume	Bag Cost	Ready-Mix	Short Load	Winner
0.25 yd3	$91	$45	+$137	Bags
0.50 yd3	$181	$90	+$116	Bags
0.75 yd3	$272	$135	+$95	Bags
1.00 yd3	$338	$180	+$74	Close
1.25 yd3	$422	$225	+$53	Close
1.50 yd3	$506	$270	+$32	Switch
2.00 yd3	$675	$360	$0*	Ready-mix
3.00 yd3	$1,013	$540	$0	Ready-mix
5.00 yd3	$1,688	$900	$0	Ready-mix

How to Use Bagged Concrete

A practical 5-step workflow for small slabs, post holes, and repair pours.

Calculate and Buy

Use the calculator to get exact bag count, add waste, and buy full bags. Ask about pallet pricing for 20+ bags.

Prepare Forms and Subbase

Compact gravel, stake forms securely, and dampen the subbase before pouring.

Mix Correctly

Follow the water ratio on the bag. Too much water is the most common cause of weak concrete.

Pour, Screed, and Finish

Place concrete quickly, screed level, finish the surface, and add control joints where needed.

Cure Properly

Keep concrete moist for at least 7 days. Avoid traffic until the slab has gained enough strength.

Need to calculate cubic yards for your project, estimate concrete slab cost including labor, or compare concrete patio cost? Use the linked guides after you have your bag count.

Concrete Bag Calculator - Frequently Asked Questions

How many bags of concrete do I need?+

The number of bags depends on project volume and bag size. One 80 lb bag yields 0.60 cubic feet. Calculate volume in cubic feet, divide by 0.60, round up, and add waste. A 10 x 10 ft patio at 4 inches thick needs 62 bags of 80 lb concrete with 10% waste.

How many 80 lb bags of concrete are in a cubic yard?+

It takes 45 bags of 80 lb concrete to make one cubic yard. One cubic yard is 27 cubic feet, and one 80 lb bag yields about 0.60 cubic feet: 27 / 0.60 = 45 bags.

How many bags of Quikrete do I need?+

Quikrete 80 lb Concrete Mix yields 0.60 cubic feet per bag. For a 10 x 10 ft slab at 4 inches thick, plan on 62 standard 80 lb Quikrete bags with 10% waste. Fast-setting post-hole mixes are usually sold in 50 lb bags.

How many bags of concrete for a 10x10 slab?+

A 10 x 10 ft slab at 4 inches thick requires about 62 bags of 80 lb concrete with 10% waste, or 82 bags of 60 lb mix. At $7.50 per 80 lb bag, material cost is about $465.

How many bags of concrete for fence posts?+

For a standard 4x4 fence post in a 10-inch diameter by 3-foot deep hole, use about 3 bags of 80 lb concrete per post. Fast-setting concrete is recommended for post holes because it can be poured dry and watered in place.

Is it cheaper to buy bags or order ready-mix?+

For projects under 1 cubic yard, bags are usually cheaper because ready-mix short-load fees make small deliveries expensive. For projects over 1.5 cubic yards, ready-mix is usually cheaper and much faster.

How long does bagged concrete take to set and cure?+

Standard concrete is usually walkable in 24-48 hours, drive-on in about 7 days, and reaches full design strength in 28 days. Fast-setting concrete can set in 20-40 minutes, but it still needs proper curing.