An 80 lb bag of concrete is the most common size on a store shelf & the one most weekend projects quietly depend on. This guide covers yield in cubic feet coverage by depth water per bag price & how many bags your slab needs.
Every bagged mix follows the same loop: volume in cubic feet divide by the yield on the bag then round up. The same divide by yield math powers our mulch calculator where bag counts for topsoil & compost work the same way.
The sections below cover yield & coverage charts a full 10 by 10 slab example water amounts & price. The concrete bag calculator parent page handles other bag sizes & the concrete calculator pillar covers ready mix yardage first.
Key Takeaways
The yield is 0.60 cubic feet
An 80 lb bag of QUIKRETE Concrete Mix yields about 0.60 cubic feet once mixed. Sakrete lists the same 0.6 figure for its 80 lb High Strength mix so the number holds across the two main bagged concrete brands sold in most U.S. hardware stores.
One bag covers 1.8 square feet at 4 inches
Coverage depends on depth because the same 0.60 cubic feet spreads thinner. At 4 inches deep one bag covers about 1.8 square feet. At 2 inches it covers 3.6 square feet & at 1 inch roughly 7.2 square feet.
Forty five bags make one cubic yard
One cubic yard holds 27 cubic feet & 27 divided by 0.60 gives exactly 45 bags. Sakrete states the same figure directly: it takes 45 bags of 80 pound mix to hit a cubic yard dead on for any full size pour.
Water starts at about 6 pints
QUIKRETE's data sheet calls for approximately 6 pints of water per 80 lb bag with a workable range near 6 to 9 pints. Add water gradually. Extra water mixes easier but permanently lowers the finished strength of the slab.
Budget 5 to 8 dollars per bag
Published 2025 benchmarks put an 80 lb bag in the 5 to 8 dollar range with individual stores listing near 6.50. Waste adds 10 percent so a 56 bag job becomes about 62 bags & the price moves with that count.
How an 80 lb Bag of Concrete Calculator Works?
A bag calculator takes length width & thickness of the pour converts them to cubic feet then divides by the 0.60 yield. The result rounds up to whole bags because stores sell them one at a time never fractions.
Most tools default to 80 lb bags & a 4 inch slab because that pairing covers most patios & shed pads. Change either input freely. The concrete bag calculator parent page runs the same math for 40 & 60 lb sizes.
How Many Cubic Feet Are in an 80 lb Bag of Concrete?
The answer is about 0.60 cubic feet which is 17 liters of wet mix. Both QUIKRETE No. 1101 & Sakrete High Strength publish the same number so switching brands rarely changes a bag count you have already calculated for the same job.
In cubic yards one bag equals 0.60 divided by 27 roughly 0.022 yards. That fraction explains why bagged concrete makes sense below half a yard & ready mix takes over near a full yard of volume on a typical driveway job.
How Much Concrete Does an 80 lb Bag Cover?
Coverage falls as depth rises because volume stays fixed at 0.60 cubic feet. Divide the yield by the depth in feet to get square feet. The chart below lists the common residential depths & the area one bag reaches.
Depth | Area per 80 lb bag |
1 inch | 7.2 sq ft |
2 inches | 3.6 sq ft |
4 inches | 1.8 sq ft |
6 inches | 1.2 sq ft |
For a full slab multiply the area by depth in feet to confirm. A patio of 200 square feet at 4 inches needs about 111 bags before waste which is where a ready mix truck quote starts to win.
How Much Water for an 80 lb Bag of Concrete?
Start near 6 pints about 3 quarts poured slowly into the dry mix while you stir. QUIKRETE lists a full range up to roughly 9 pints for workability but the bag only needs enough to reach a plastic consistency.
Too much water weakens the slab & leaves bleed puddles on the surface. Mix to a thick oatmeal texture check that no dry powder hides at the bottom & add water only in small splashes after the first pass.
How Many 80 lb Bags of Concrete Are in a Cubic Yard?
Forty five. One cubic yard equals 27 cubic feet & each bag yields 0.60 so 27 divided by 0.60 returns exactly 45. Order 50 bags when the pour sits at a full yard to cover waste & uneven ground.
Beyond one yard the counting flips. Carrying 45 bags moves 1.5 tons of powder into your driveway so most builders switch to a ready mix truck somewhere between one & two yards of calculated volume for the whole project.
How Many 80 lb Bags for a 10 by 10 Slab?
A 10 by 10 foot slab at 4 inches holds 100 square feet times one third foot which is 33.33 cubic feet. Divide by 0.60 & you need 56 bags minimum before any waste allowance is added on top.
Add 10 percent & the order becomes 62 bags. That buffer covers spillage a subgrade that dips low & the two bags that always crack open early. Buy them together because dye lots & stock vary by store & season.
Bag Counts for Common Slab Sizes
Run the same loop for any rectangle: the concrete slab calculator gives volume first then divide cubic feet by 0.60 & round up. The table below uses 4 inch depth before the 10 percent waste buffer we add everywhere.
Slab size | Cubic feet | Bags at 4 in |
10 × 10 | 33.3 | 56 |
10 × 12 | 40 | 67 |
12 × 12 | 48 | 80 |
20 × 20 | 133.3 | 223 |
Past about 100 bags the arithmetic changes sides. Eighty pound bags become a hauling job so call for a ready mix quote at that point & compare the delivered price against your bag totals before you drive to the store.
How Much Does an 80 lb Bag of Concrete Cost?
Published 2025 guides list an 80 lb bag between 5 & 8 dollars with typical store shelves near 6.50. Price drops on bulk pallets so ask about case pricing when a job needs more than 20 bags for one pour.
At 6.50 per bag a 56 bag slab costs about 364 dollars in material alone. One cubic yard of ready mix delivered usually lands near 150 to 200 dollars which is why bags lose past the half yard mark.
Bags for Post Holes & Round Footings
Round holes flip the order: measure the volume first then count bags. A 10 inch post hole 1 foot deep holds about 0.55 cubic feet which needs one 80 lb bag with a little mix left over for bracing.
The same pi times radius squared formula runs inside every calculator. Square pads stay simpler: area times depth in feet gives cubic feet then the familiar divide by 0.60 counts the bags you carry out to the truck bed.
One Bag One Batch: Mixing Without Waste
Sakrete's hand mixing guide sets one 80 lb bag per batch in a wheelbarrow or mortar tub while a mechanical mixer takes two bags at most. Empty the bag fully add water first then pour in the powder slowly.
Mixing two bags at once doubles the wet weight & most people add too much water to the second bag. Keep batches single scrape the corners & pour within about 30 minutes so the slab sets as one continuous piece.
Conclusion
An 80 lb bag of concrete yields about 0.60 cubic feet & covers about 1.8 square feet at 4 inches deep. Calculate the volume first then divide by the bag yield & round up to whole bags. Add 10 percent for waste before placing your order.
Check the water amount printed on your bag & never eyeball the amount. Whether you are pouring a shed pad or setting a mailbox post the same math applies every time: measure the space convert the dimensions divide by the yield & round up before buying a single bag.
FAQs
How do I calculate how many bags of concrete I need?
Find the volume in cubic feet with length times width times thickness in feet then divide by 0.60 & round up. Add 10 percent for waste. A quick check: one bag covers 1.8 square feet at 4 inches deep.
Can I mix an 80 lb bag of concrete in a 5 gallon bucket?
Manufacturers do not recommend it. A full bag needs a wheelbarrow or mortar tub for proper mixing room & a 5 gallon bucket only works for partial batches. Sakrete sets one bag as the hand mixing maximum per batch.
How much does an 80 lb bag of concrete cover?
Near 7.2 square feet at 1 inch 3.6 at 2 inches & 1.8 at 4 inches. Divide 0.60 cubic feet by the depth in feet for any other thickness. Always add waste before you count bags for a pour.
Is it cheaper to buy bags or order ready mix?
Below half a yard bags usually win on total cost. Past one yard ready mix delivery beats 45 or more bags on price labor & consistency. Get a delivered quote near your yardage number & compare it against bag totals.
Do 80 lb bags come on a pallet?
Yes. QUIKRETE lists 42 bags per pallet for its 80 lb 5000 mix while the official count for the standard 1101 mix stays unlisted. Pallet pricing still drops the per bag cost which helps jobs that need 40 bags or more.
Does the brand change the bag count?
Not usually. QUIKRETE & Sakrete both publish 0.60 cubic feet for an 80 lb bag so the same volume math returns the same count. Check the yield printed on your bag when a store brand or specialty mix differs.
How much water does an 80 lb bag of concrete need?
Start at 6 pints about 3 quarts added slowly while mixing. QUIKRETE allows up to roughly 9 pints for workability but extra water cuts strength so stop as soon as the mix looks uniformly wet & plastic enough to hold a shape.
