Concrete Calculator
Enter a slab's length, width and thickness, add more slabs to the same pour, and get the concrete to buy in bags, with every step shown. A slab that is not a rectangle can be drawn with Draw a shape.
Estimates for planning, not professional advice. Read the full notice.
Shape
The drawing did not open. Length and width are still here.
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
- + on a corner
- add a corner halfway along the next side
- Arrow keys on the drawing
- move the view; farther with Shift
- + and - on the drawing
- zoom in and out
- 0 on the drawing
- show the whole shape
- Ctrl+Z (Cmd+Z on a Mac)
- undo, except inside a typed field (it keeps its own)
- Ctrl+Shift+Z or Ctrl+Y
- redo
- Escape while dragging
- put it back where it was
- Enter on a corner or side
- go to its actions
- Escape in the actions
- close them and go back to the drawing
The drawing did not load. Check your connection and try again.
- 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"
Product names are trademarks of their owners. HoneyDoMath is not affiliated with, sponsored by or endorsed by these makers. Figures come from each maker's published sheets and are shown for information only.
Example: a slab
62 80 lb bags
- Concrete in the slab 33.33 ft³
- To mix, with waste 36.67 ft³
- 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.
Shopping list
| Item | Size | Buy |
|---|---|---|
| Concrete mix | 80 lb bag | 62 |
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Worked example: a slab
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"
Volume by shape
Concrete volume and bags to buy for common shapes
| Shape and sizes | Volume, without waste | To order, with waste | In 80 lb bags |
|---|---|---|---|
| Footing, 40 ft × 16 in × 8 in | 35.56 ft³ | 1.45 yd³ | 66 × 80 lb bags |
| Square column, 16 in × 16 in × 8 ft | 14.22 ft³ | 0.58 yd³ | 27 × 80 lb bags |
| Steps, 3 risers of 7 in with 11 in treads, 4 ft wide, 3 ft platform | 27.42 ft³ | 1.12 yd³ | 51 × 80 lb bags |
| Round slab, 10 ft across × 4 in | 26.18 ft³ | 1.07 yd³ | 48 × 80 lb bags |
Each shape in this table is worked out on its own, with the waste allowance added and the bags rounded up for that shape alone. The calculator on this page takes slabs; it does not work out footings, columns or steps.
Yield per bag, by maker and mix
What one bag yields, for each concrete mix and bag size the calculator offers, as its maker states
| Mix and bag size | Yield per bag |
|---|---|
| QUIKRETE 5000 High Early Strength Concrete Mix, 50 lb | approx. 0.375 ft³ (per QUIKRETE's data sheet, checked Nov 12, 2026) |
| QUIKRETE 5000 High Early Strength Concrete Mix, 60 lb | approx. 0.45 ft³ (per QUIKRETE's data sheet, checked Nov 12, 2026) |
| QUIKRETE 5000 High Early Strength Concrete Mix, 80 lb | approx. 0.6 ft³ (per QUIKRETE's data sheet, checked Nov 12, 2026) |
| QUIKRETE Concrete Mix 1101, 40 lb | approx. 0.3 ft³ (per QUIKRETE's data sheet, checked Nov 12, 2026) |
| QUIKRETE Concrete Mix 1101, 50 lb | approx. 0.375 ft³ (per QUIKRETE's data sheet, checked Nov 12, 2026) |
| QUIKRETE Concrete Mix 1101, 60 lb | approx. 0.45 ft³ (per QUIKRETE's data sheet, checked Nov 12, 2026) |
| QUIKRETE Concrete Mix 1101, 80 lb | approx. 0.6 ft³ (per QUIKRETE's data sheet, checked Nov 12, 2026) |
| QUIKRETE Concrete Mix 1101, 90 lb | approx. 0.675 ft³ (per QUIKRETE's data sheet, checked Nov 12, 2026) |
| QUIKRETE Crack Resistant Concrete Mix, 50 lb | approx. 0.375 ft³ (per QUIKRETE's data sheet, checked Nov 12, 2026) |
| QUIKRETE Crack Resistant Concrete Mix, 60 lb | approx. 0.45 ft³ (per QUIKRETE's data sheet, checked Nov 12, 2026) |
| QUIKRETE Crack Resistant Concrete Mix, 80 lb | approx. 0.6 ft³ (per QUIKRETE's data sheet, checked Nov 12, 2026) |
| QUIKRETE Fast-Setting Concrete Mix 1004, 50 lb | approx. 0.375 ft³ (per QUIKRETE's data sheet, checked Nov 12, 2026) |
| QUIKRETE Fast-Setting Concrete Mix 1004, 60 lb | approx. 0.45 ft³ (per QUIKRETE's data sheet, checked Nov 12, 2026) |
| QUIKRETE Q•MAX PRO Concrete Mix, 50 lb | approx. 0.375 ft³ (per QUIKRETE's data sheet, checked Nov 12, 2026) |
| QUIKRETE Q•MAX PRO Concrete Mix, 80 lb | approx. 0.6 ft³ (per QUIKRETE's data sheet, checked Nov 12, 2026) |
| Rapid Set CONCRETE MIX, 60 lb | approx. 0.5 ft³ (per Rapid Set's published data, checked Nov 12, 2026) |
| SAKRETE 5000 Plus Concrete Mix, 50 lb | 0.38 ft³ (per SAKRETE's data sheet, checked Nov 12, 2026) |
| SAKRETE 5000 Plus Concrete Mix, 60 lb | 0.47 ft³ (per SAKRETE's data sheet, checked Nov 12, 2026) |
| SAKRETE 5000 Plus Concrete Mix, 80 lb | 0.6 ft³ (per SAKRETE's data sheet, checked Nov 12, 2026) |
| SAKRETE Crack-Resistant Concrete Mix, 50 lb | 0.38 ft³ (per SAKRETE's data sheet, checked Nov 12, 2026) |
| SAKRETE Crack-Resistant Concrete Mix, 80 lb | 0.6 ft³ (per SAKRETE's data sheet, checked Nov 12, 2026) |
| SAKRETE Fast Setting Concrete Mix, 50 lb | 0.38 ft³ (per SAKRETE's data sheet, checked Nov 12, 2026) |
| SAKRETE High Strength Concrete Mix, 40 lb | 0.3 ft³ (per SAKRETE's data sheet, checked Nov 12, 2026) |
| SAKRETE High Strength Concrete Mix, 60 lb | 0.45 ft³ (per SAKRETE's data sheet, checked Nov 12, 2026) |
| SAKRETE High Strength Concrete Mix, 80 lb | 0.6 ft³ (per SAKRETE's data sheet, checked Nov 12, 2026) |
| SAKRETE High Strength Concrete Mix, 90 lb | 0.66 ft³ (per SAKRETE's data sheet, checked Nov 12, 2026) |
| SAKRETE Maximizer Concrete Mix, 40 lb | 0.46 ft³ (per SAKRETE's data sheet, checked Nov 12, 2026) |
| SAKRETE Maximizer Concrete Mix, 80 lb | 0.92 ft³ (per SAKRETE's data sheet, checked Nov 12, 2026) |
| SAKRETE Pro-Mix Advanced Concrete Mix, 50 lb | 0.375 ft³ (per SAKRETE's data sheet, checked Nov 12, 2026) |
Product names are trademarks of their owners. HoneyDoMath is not affiliated with, sponsored by or endorsed by these makers. Figures come from each maker's published sheets and are shown for information only.
Sources: [3][2][4][5][6][7][8][9][10][11][12][13]
The list is in alphabetical order by maker, then by mix. Your bag's label comes first. If it says something different, use the label.
Questions
How do I calculate concrete for more than one slab?
Work out each slab's volume, add the volumes together, add the waste allowance to the total, then divide by the yield of your bag. Rounding up happens once, at the end. In the calculator, each slab you add is one item of the same pour.
Why add the slabs before rounding up?
Rounding each slab up to whole bags first can add a bag or two that the whole pour does not need. The calculator adds the exact volumes first and rounds up once, so the count matches the pour.
How do I find the volume of a round column or a tube form?
Take the area of the circle from the diameter, multiply by the depth, and multiply by how many there are. The calculator on this page does not take columns or tubes; the volume by shape table below works out a round slab this way.
How much extra concrete should I order?
The National Ready Mixed Concrete Association says to order a little more than the estimate worked out from the plan dimensions, to cover contingencies. The waste allowance is a starting value you can change.
Where do the bag yields come from?
From the bag maker's own data sheet, listed under Sources with the date it was checked. Other mixes and other makers can yield differently, so read your own bag's label.
Sources (13)
-
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.”
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) -
QUIKRETE 5000 High Early Strength Concrete Mix No. 1007 data sheet (opens in new tab), The Quikrete Companies, Revised November 2022.
Manufacturer data.
“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)”
“An 80 lb (36.2 kg) bag yields approximately 0.60 ft3 (17 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 3) -
QUIKRETE Crack Resistant Concrete Mix No. 1006 data sheet (opens in new tab), The Quikrete Companies, Revised December 2021.
Manufacturer data.
“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)”
“An 80 lb (36.2 kg) bag yields approximately 0.60 ft3 (17 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 4) -
QUIKRETE Fast-Setting Concrete Mix No. 1004 data sheet (opens in new tab), The Quikrete Companies, Revised November 2025.
Manufacturer data.
“Each 50 lb (22.6 kg) bag yields approximately 0.375 cu ft (10.6 L)”
“Each 60 lb (27.2 kg) bag yields approximately 0.45 cu ft (12.7 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 5) -
QUIKRETE Q•MAX PRO Concrete Mix No. 1004-81 data sheet (opens in new tab), The Quikrete Companies, Revised April 2022.
Manufacturer data.
“A 50 lb (22.6 kg) bag and an 80 lb (36.2 kg) bag of QUIKRETE Q•MAX PRO Concrete Mix will yield approximately 0.375 ft3 (10.6 L) and 0.6 ft3 (16.9 L) respectively, at the recommended consistency.”
Per QUIKRETE's data sheet, checked Nov 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 6) -
Rapid Set CONCRETE MIX datasheet DS_004_EN (opens in new tab), CTS Cement Manufacturing Corporation (Rapid Set), Datasheet DS_004_EN, web view, © 2026.
Manufacturer data.
“One 60-lb (27.2-kg) bag of CONCRETE MIX will yield approximately 0.5 ft3 (0.01 m3).”
Per Rapid Set's published data, checked Nov 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 7) -
SAKRETE 5000 Plus Concrete Mix technical data sheet (opens in new tab), SAKRETE of North America, Technical data sheet, 2023 (sakrete.com copy).
Manufacturer data.
“50 lb 0.38 ft3 2.1 qts”
“60 lb 0.47 ft3 2.5 qts”
“80 lb 0.6 ft3 3.5 qts”
Per SAKRETE's data sheet, checked Nov 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 8) -
SAKRETE Crack-Resistant Concrete Mix technical data sheet (opens in new tab), SAKRETE of North America, Technical data sheet, no date read (sakrete.com copy).
Manufacturer data.
“50 lb 22.7 kg 0.38 ft3 0.01 m3”
“80 lb 36.3 kg 0.6 ft3 0.017 m3”
Per SAKRETE's data sheet, checked Nov 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 9) -
SAKRETE Fast Setting Concrete Mix technical data sheet (opens in new tab), SAKRETE of North America, Rev. 05/18.
Manufacturer data.
“50 lb (22.6 kg) 0.38 ft3 (.01 m3) 2.5 to 3 qts (2.4 - 2.9 L)”
Per SAKRETE's data sheet, checked Nov 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 10) -
SAKRETE High Strength Concrete Mix technical data sheet (opens in new tab), SAKRETE of North America, Technical data sheet, 2023 (sakrete.com copy).
Manufacturer data.
“40 lb 0.30 ft3 1.75 qts”
“60 lb 0.45 ft3 2.5 qts”
“80 lb 0.6 ft3 3.5 qts”
“90 lb 0.66 ft3 4.25 qts”
Per SAKRETE's data sheet, checked Nov 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 11) -
SAKRETE Maximizer Concrete Mix technical data sheet (opens in new tab), SAKRETE of North America, File name dated 04-24 (sakrete.com copy).
Manufacturer data.
“40 lb 18.1 kg 0.46 ft3 0.013 m3”
“80 lb 36.3 kg 0.92 ft3 0.026 m3”
Per SAKRETE's data sheet, checked Nov 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 12) -
SAKRETE Pro-Mix Advanced Concrete Mix technical data sheet (opens in new tab), SAKRETE of North America, Technical data sheet, no date read (sakrete.com copy).
Manufacturer data.
“50 lb 22.7 kg 0.375 ft3 0.01 m3”
Per SAKRETE's data sheet, checked Nov 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 13)
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
- [3] QUIKRETE, QUIKRETE 5000 High Early Strength Concrete Mix No. 1007 data sheet. Checked November 12, 2026. https://www.quikrete.com/PDFs/DATA_SHEET-QUIKRETE%205000%201007.pdf
- [4] QUIKRETE, QUIKRETE Crack Resistant Concrete Mix No. 1006 data sheet. Checked November 12, 2026. https://www.quikrete.com/PDFs/DATA_SHEET-Crack%20Resistant%20Concrete%20Mix%201006-80.pdf
- [5] QUIKRETE, QUIKRETE Fast-Setting Concrete Mix No. 1004 data sheet. Checked November 12, 2026. https://www.quikrete.com/PDFs/DATA_SHEET-Fast%20Setting%20Concrete%20Mix%201004-50.pdf
- [6] QUIKRETE, QUIKRETE Q•MAX PRO Concrete Mix No. 1004-81 data sheet. Checked November 12, 2026. https://www.quikrete.com/PDFs/DATA_SHEET-QMAX-PRO-1004-81.pdf
- [7] Rapid Set, Rapid Set CONCRETE MIX datasheet DS_004_EN. Checked November 12, 2026. https://www.ctscement.com/datasheet/CONCRETE_MIX_Datasheet_DS_004_EN
- [8] SAKRETE, SAKRETE 5000 Plus Concrete Mix technical data sheet. Checked November 12, 2026. https://www.sakrete.com/wp-content/uploads/2021/07/Sakrete-5000-Plus-TDS.pdf
- [9] SAKRETE, SAKRETE Crack-Resistant Concrete Mix technical data sheet. Checked November 12, 2026. https://www.sakrete.com/wp-content/uploads/2021/07/Sakrete-Crack-Resistant-Concrete-TDS.pdf
- [10] SAKRETE, SAKRETE Fast Setting Concrete Mix technical data sheet. Checked November 12, 2026. https://www.sakrete.com/wp-content/uploads/2021/07/Fast-Setting-Concrete.pdf
- [11] SAKRETE, SAKRETE High Strength Concrete Mix technical data sheet. Checked November 12, 2026. https://www.sakrete.com/wp-content/uploads/2024/01/Sakrete-High-Strength-Concrete-Mix-TDS.pdf
- [12] SAKRETE, SAKRETE Maximizer Concrete Mix technical data sheet. Checked November 12, 2026. https://www.sakrete.com/wp-content/uploads/2024/09/Sakrete-Maximizer-Concrete-Mix-TDS-04-24.pdf
- [13] SAKRETE, SAKRETE Pro-Mix Advanced Concrete Mix technical data sheet. Checked November 12, 2026. https://www.sakrete.com/wp-content/uploads/2023/02/Pro-Mix-Advanced-Concrete-Mix-TDS-1.pdf