Concrete Steps Calculator
Find how much concrete you need for solid concrete steps or stairs, and how many bags of concrete mix to buy. Enter the number of steps, the riser height, the tread depth, the width, and the depth of the top landing.
- Choose US or Metric. This also sets the bag sizes in the results: 80, 60, 50, and 40 lb bags for US, and 30 and 20 kg bags for Metric.
- Enter the number of Steps. Count each step up, including the one onto the top step or landing. Two steps up to a door is 2.
- Enter the Tread depth, from the face of one riser to the face of the next, the Riser height, and the Stair width from side to side.
- If the top step is deeper than the others, such as a landing in front of a door, enter its depth from its front edge to the back in Landing depth. Leave it blank to make the top step as deep as the others.
- Keep the 10% waste allowance or change it. If your bag size is not listed, enter the yield printed on the bag in Custom bag yield.
- Optionally, enter a price per bag, per custom bag, or per cubic yard, cubic foot, or cubic meter to estimate the cost. Use a bag price from your store or a ready-mix quote.
Length fields accept whole numbers, decimals, fractions, and mixed
numbers, such as 7, 10.5, 3/4, or
7 1/2.
If you laid out the stair with the Stair Calculator, enter its Risers as Steps, and its riser height and tread depth here. Total depth in the results is the stair's Total run plus the depth of the top step or landing, because the top step is part of the concrete. It is the length of ground the forms cover.
How much concrete steps need
The calculator treats each step as a solid block from its top down to the ground, and the top step or landing as one block. Adding up the blocks gives:
Lower steps = width × riser height × tread depth × (steps − 1) × steps ÷ 2
Top step = width × top step depth × total rise
Total rise = steps × riser height
The step at the bottom is one riser tall, the next is two, and so on, so the lower steps add up to 1 + 2 + … + (steps − 1) risers of height. The top step depth is the landing depth, or the tread depth if you leave the landing blank. Convert every dimension to the same unit before you multiply. With dimensions in inches, divide cubic inches by 1,728 to get cubic feet, and cubic feet by 27 to get cubic yards.
The waste allowance is added to the net volume: total = net volume × (1 + waste % ÷ 100). The number of bags is the total volume divided by the yield of one bag, rounded up:
| Bag | Yield |
|---|---|
| 80 lb | 0.60 ft³ |
| 60 lb | 0.45 ft³ |
| 50 lb | 0.375 ft³ |
| 40 lb | 0.30 ft³ |
| 30 kg | 14 L |
| 20 kg | 9.26 L |
These are the same yields as the Concrete Calculator, from the Quikrete, Bomix, and Boral data sheets. Yields differ between products, so check the label on the bag you buy. The 10% waste allowance follows Sakrete's advice to add 10% to an estimate for bagged concrete.
Step size and US code limits
Quikrete's guide to concrete steps suggests making the steps at least as wide as the door and walk they serve, a landing at least 3 ft deep, and a tread of 10 to 11 in for a riser of 7 to 7 1/2 in. The 2024 International Residential Code (IRC) sets these limits for stairs in houses:
| Measurement | IRC limit |
|---|---|
| Riser height | 7 3/4 in (196 mm) or less |
| Tread depth | 10 in (254 mm) or more |
| Landing at the top of a straight stair | 36 in (914 mm) or more in the direction of travel |
The calculator adds a note when the riser height or tread depth falls outside these limits. It does not check the landing or anything else. The IRC section on stairs does not apply to steps that are not part of, and do not serve, a building, porch, or deck, such as garden steps. US states and cities adopt the IRC with their own changes, and the rules differ outside the US, so check the code where you build.
Examples
Three steps
Three steps with 7 in risers and 11 in treads, 48 in wide, are 12.83 ft³ of concrete: 6.42 ft³ for the two lower steps and 6.42 ft³ for the top step. With a 10% waste allowance, the total is 14.12 ft³, or 0.52 yd³. That's 24 bags of 80 lb (14.12 ÷ 0.60 = 23.53, rounded up) or 48 bags of 40 lb.
Steps up to a landing
For the same steps with a 36 in deep landing at the top, the landing is 48 × 36 × 21 in, or 21.00 ft³. With the two lower steps and 10% added, the total is 30.16 ft³, or 1.12 yd³. That's 51 bags of 80 lb, which cost $331.50 at $6.50 a bag. The forms cover 4 ft 10 in of ground.
Metric dimensions
Three steps with 170 mm risers and 300 mm treads, 1,000 mm wide, are 0.306 m³. With 10% added, the total is 0.34 m³, which is 25 bags of 30 kg or 37 bags of 20 kg.
FAQ
About 24 bags of 80 lb for three steps 48 in wide with 7 in risers and 11 in treads, with a 10% waste allowance. That's 0.52 yd³. A deeper top step or a wider stair needs more, so enter your sizes in the calculator.
Treat each step as a block from its top to the ground: the tread depth × the step's height above the ground × the width. Add the blocks, and the top step or landing as one more block, then add 10% for waste and divide by the yield of a bag.
Yes. Count the step up onto the landing in Steps, and enter the landing's depth in Landing depth. The landing is the top step, so it isn't added again on top of the last tread.
It depends on the prices near you. Enter the price of a bag of concrete mix to see the cost in bags, or switch the price to per cubic yard or cubic meter and enter a ready-mix quote. The calculator estimates the concrete only, not labor, forms, or rebar.
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