Concrete Cost Calculator: Bags vs Ready-Mix
Enter the size of a pour and your own prices and get the bags and the ready-mix yards for it, both totals and the gap between them. The prices are yours: the page knows none and keeps none.
Estimates for planning, not professional advice. Read the full notice.
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Slab: shape and size
Skip the drawingDrag a round corner to move it. The small hollow diamond on a side is its curve handle: drag it across the side to curve the side (it is not a corner). To add a corner (a new point), tap the side itself, then choose Add a point here. Tapping a corner or a side opens its actions. Drag empty space to move the view; pinch, or Ctrl and the mouse wheel, to zoom. The keys are listed under Keys.
Keys
- Tab
- next corner; each says how far it is from corner 1
- Arrow keys on a corner
- move it one square; ten with Shift; 1/16 in with Alt
- Delete or Backspace
- remove the corner; its two sides join in one straight side
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- undo, except inside a typed field (it keeps its own)
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- redo
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- Area
- 100 ft²
- Perimeter
- 40 ft
- Cut-out edges
No area until the shape is fixed.
Estimate for planning, from what you entered and the product data shown. Check product labels and your supplier before you buy.
Shape: Rectangle Change
Sides
Corners
Cut-outs
Feet and inches, like 12' 6"
Example: a slab, bags and ready-mix
62 80 lb bags
- Concrete in the slab 33.33 ft³
- To mix, with waste 36.67 ft³
- Ready-mix to order, with waste 1.36 yd³
Your project
Enter a size to see your total.
Each product is rounded up once for the whole project, so the total can be less than the items bought alone added together. A line counted from a cut layout (sheets, boards or tiles laid out piece by piece) is counted for each item and added.
Your prices
Type your own prices. They stay on this device: nothing is stored or sent, and this page has no price of its own to start from. A blank box is no price, not zero.
From your own receipt or shelf, for the bag size chosen above.
Ask your supplier.
Ask your supplier. Blank means no step.
Ask your supplier. Blank means none.
Ask your supplier.
Ask your supplier. Charged once when the order is under the minimum load.
Pump, fuel or anything else your supplier adds.
Ask your supplier. The ready-mix industry body gives a range for truck mixers; the table on this page shows it. The count starts at the smallest, so it never under-buys.
Shopping list
| Item | Size | Buy |
|---|---|---|
| Concrete mix | 80 lb bag | 62 |
| Ready-mix concrete | 1 yd³ | 1.5 yd³ |
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Worked example: a slab, bags and ready-mix
Assumptions
The figures behind the example. Sourced figures link to their source below; a default is a starting value to check against your label or supplier.
| Assumption | Value | Details and changes |
|---|---|---|
| Concrete waste allowance | 10%[1] | |
| Default 10% is the top of NRMCA's 4% to 10% range. | ||
| Yield of the 40 lb bag | approx. 0.3 ft³[2] | |
| A 40 lb bag of QUIKRETE Concrete Mix 1101 yields about this many cubic feet, as the maker's own sheet states. | ||
| Yield of the 50 lb bag | approx. 0.375 ft³[2] | |
| A 50 lb bag of QUIKRETE Concrete Mix 1101 yields about this many cubic feet, as the maker's own sheet states. | ||
| Yield of the 60 lb bag | approx. 0.45 ft³[2] | |
| A 60 lb bag of QUIKRETE Concrete Mix 1101 yields about this many cubic feet, as the maker's own sheet states. | ||
| Yield of the 80 lb bag | approx. 0.6 ft³[2] | |
| An 80 lb bag of QUIKRETE Concrete Mix 1101 yields about this many cubic feet, as the maker's own sheet states. | ||
| Yield of the 90 lb bag | approx. 0.675 ft³[2] | |
| A 90 lb bag of QUIKRETE Concrete Mix 1101 yields about this many cubic feet, as the maker's own sheet states. | ||
Feet and inches, like 12' 6"
Bags and yards for common pours
Concrete with waste, 80 lb bags and truck loads for common slabs, quantities only
| Pour (length × width × thickness) | Concrete with waste | 80 lb bags | Truck loads at the smallest truck (8 yd³) | Truck loads at the largest truck (12 yd³) |
|---|---|---|---|---|
| 10 ft × 10 ft × 4 in | 1.36 yd³ | 62 × 80 lb bags | 1 load | 1 load |
| 12 ft × 12 ft × 4 in | 1.96 yd³ | 88 × 80 lb bags | 1 load | 1 load |
| 20 ft × 20 ft × 4 in | 5.43 yd³ | 245 × 80 lb bags | 1 load | 1 load |
| 20 ft × 20 ft × 6 in | 8.15 yd³ | 367 × 80 lb bags | 2 loads | 1 load |
Quantities only: the prices come from you, in the panel above. Truck loads are counted at the smallest capacity in the cited range, 8 yd³, so the count never under-buys; the largest is shown beside it. Your supplier's truck may differ. The bag yields come from QUIKRETE's published sheet. Product names are trademarks of their owners. HoneyDoMath is not affiliated with, sponsored by or endorsed by these makers.
How much a truck mixer carries
The range of ready-mixed concrete a truck mixer carries, from the industry body's ordering guide
| Figure | Smallest | Largest |
|---|---|---|
| Truck mixer capacity | 8 yd³ | 12 yd³ |
Source: [1]
Your supplier's truck may differ: type its capacity in the panel above.
Questions
Is it cheaper to mix bags or buy ready-mix?
The calculator shows both totals from the prices you type, and the difference between them, for the pour you entered. It holds no price of its own, so the answer is in your numbers.
What is a short-load fee?
A flat fee some suppliers add when an order is under their minimum load. It is an input in the price panel; ask your supplier whether one applies.
What is a minimum load?
The smallest amount a supplier will deliver. If your order is under it, the panel bills the minimum and adds the short-load fee you typed, line by line.
How does the break-even work?
It finds the cubic yards at which the two totals are equal, from the prices and fees you typed, and says so when ready-mix is higher or lower at every size.
Sources (2)
-
CIP 31, Ordering Ready Mixed Concrete (opens in new tab), National Ready Mixed Concrete Association, 2000, 2016, 2023.
Standards or industry body.
“Quantity of concrete ordered should be 4% to 10% more than an estimate calculated from the plan dimensions to account for contingencies.”
“The capacity of truck mixers varies between 8 to 12 cubic yards (5 to 9 m3).”
Checked November 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 1) -
QUIKRETE Concrete Mix No. 1101 data sheet (opens in new tab), The Quikrete Companies, Revised October 2022.
Manufacturer data.
“An 80 lb (36.2 kg) bag yields approximately 0.60 ft3 (17 L)”
“A 40 lb (18.1 kg) bag yields approximately 0.30 ft3 (8.5 L)”
“A 50 lb (22.6 kg) bag yields approximately 0.375 ft3 (10.6 L)”
“A 60 lb (27.2 kg) bag yields approximately 0.45 ft3 (12.7 L)”
“A 90 lb (40.8 kg) bag yields approximately 0.675 ft3 (19.1 L)”
Per QUIKRETE's data sheet, checked Nov 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 2)
These are summaries of what the sources say, not professional advice. Codes and product data change. Check with your building department and the product label about your own project.
Sources
- [1] National Ready Mixed Concrete Association, CIP 31, Ordering Ready Mixed Concrete. Checked November 12, 2026. https://www.nrmca.org/wp-content/uploads/2021/01/31pr.pdf
- [2] QUIKRETE, QUIKRETE Concrete Mix No. 1101 data sheet. Checked November 12, 2026. https://www.quikrete.com/PDFs/DATA_SHEET-Concrete%20Mix%201101.pdf