How do the Calculator.net and myCarpentry stair calculators compare?
Published · By Sai Nath
All three are free. Calculator.net's stair calculator shows feet-inches and centimetres side by side and warns when headroom falls short; myCarpentry's cites the 2024 IRC and gives the first-step cut; MeisterCalc's checks four countries' rules. For a 9' 1 1/8" rise, Calculator.net (checked 1 November 2026) and MeisterCalc both give 16 rises of 6.82".
We make MeisterCalc, so read this with that in mind. Every fact about Calculator.net and myCarpentry comes from their own pages (Calculator.net, myCarpentry), read on 1 November 2026 and linked where the fact appears; the Calculator.net results below are what its page returned that day for the inputs we give. We did not run myCarpentry's calculator, so we describe it from its page. MeisterCalc's figures come from its own formula code. Checked on 1 November 2026.
What do the three free stair calculators do?
All three work out the risers, run, stringer and angle of a straight stair from the total rise. They differ in what they add: Calculator.net checks headroom at your floor opening, myCarpentry gives cutting figures and quotes the IRC, and MeisterCalc gives the opening size and checks the stair against the rules of the country you pick. Checked on 1 November 2026; each row links the page it comes from.
| Checked on 1 November 2026 | |||
|---|---|---|---|
| What you get | Calculator.net | myCarpentry | MeisterCalc |
| Made by | calculator.net, “© 2008 - 2026” (source) | Matt Bray, “a carpenter, programmer, and sole contributor” (source) | Meru Apps |
| Ways to enter a stair | Basic and Comprehensive versions; one run or total run; a fixed rise or a fixed number of steps (source) | Automatic: total rise, a target step height from 4.00 to 8.50 in, tread depth 9 to 12 in. Manual: total rise, total run and number of risers (source) | Rise only, Rise + run, Run only, and Riser Limited to keep every riser under your limit |
| Units | Each field in feet, inches, metres or centimetres; results in both systems (source) | Inches, and a separate millimetres page | Millimetres, or feet and inches to the nearest 1/16", on one page |
| Tread thickness | Optional; gives the first step height with and without the tread (source) | Yes: the first step is cut to the step height less the tread thickness (source) | Not deducted; take it off by hand |
| Headroom | Checks the headroom at the floor opening you enter, with a “Headroom Requirement Not Met” warning (source) | A code note: not less than 6' 8" (source) | Gives the stairwell opening length for your floor thickness and headroom |
| Stringer | Length, height and placement; standard or flush mount (source) | Length as “the minimum length of 2x12 material required”, placement, standard or flush mount (source) | Line length and angle |
| Building rules | Figures that “Building codes generally suggest”, and a note to check local codes (source) | Quotes IRC limits, links the 2024 IRC and flags “Some results may not meet code requirements” (source) | Checks against the IRC, NCC 2025, D1/AS1 or Approved Document K, quoted with sources |
| Drawing | A reference figure beside the calculator (source) | A diagram with lettered dimensions, [A] to [H] (source) | Your stair drawn to scale |
| Landings | No landing input (source) | Explained in text and in a separate stairs and landings article | No landings |
| On a phone | The web page (source) | The web page; its page says “The old Mobile Stair Calculator … will be deprecated soon” (source) | The web page, and Stairs in the Android app, which is free and works offline |
How do you use the Calculator.net stair calculator?
Use the Comprehensive version, enter the run of one tread and the total rise, and choose “Fixed number of steps” rather than “Fixed rise”. The Calculator.net stair calculator has a Basic version (run or total run, and total rise) and a Comprehensive one that adds the rise setting, tread thickness, a headroom restriction (floor opening, floor thickness, headroom required) and a standard or flush stringer mount. It returns the rise, total run, number of steps, stringer length and height, angle, headroom, first step heights and stringer placement, each in feet-inches and in centimetres.
Two things we found when we ran it on 1 November 2026, both with a 109 1/8" total rise and a 10" run (Calculator.net stair calculator):
- “Fixed rise” keeps the rise you type and puts the rest in the first step. With a fixed rise of 7.75 in it returned Rise 7.75 inches, Number of Steps 14 and a First Step Height of 0.63 inch: 14 × 7.75 = 108.5 in, and the last 5/8" goes to the first step. The IRC wants risers in a flight within 3/8" of each other (City of Boise IRC handout, PDF), so for a real stair let it share the rise with “Fixed number of steps”.
- Its number of steps is one less than the rises. Fixed number of steps 15 returned Rise 6.82 inches, which is 109.125 ÷ 16, and Total Run 12 feet 6 inches, which is 15 × 10". So 15 steps means 16 rises. Check the Rise figure rather than the step count.
Its code figures are general: “Building codes generally suggest that the maximum height of a riser be 7.75 inches (19.7 cm)”, and “a person building a staircase should refer to the codes specific to their locations” (Calculator.net).
How does the myCarpentry stair calculator work?
You enter the total rise and pick a target step height, tread thickness and tread depth from lists, and it returns the cut figures for the stringer. The myCarpentry stair calculator has an Automatic form (target step height 4.00 to 8.50 in, in quarter inches; tread depth 9 to 12 in) and a Manual one where you give the total run and the number of risers. Results come as fractions and decimals: number of steps (risers), steps on stringer, height of first step, height of typical step, stringer placement, total run, stringer length and the stair/rail angle.
- When you cut the stringer, “the First Step Height [E] is always the Step Height [F] minus the Tread Thickness [C]”, so the first notch is ready to cut (myCarpentry).
- The stringer length “is the minimum length of 2x12 material required to lay out and cut the stringer” (myCarpentry).
- With a standard mount, “the number of risers will be one more than the number of Steps on Stringer [D]” (myCarpentry).
- For the rules it links the “2024 International Residential Code for One- and Two-Family Dwellings - Section 318 - MEANS OF EGRESS” and has a “Some results may not meet code requirements” warning that asks you to adjust the inputs (myCarpentry).
A metric version does the same in millimetres. We found no myCarpentry app on Google Play or the App Store when we searched on 1 November 2026.
Worked example: a 9' 1 1/8" floor-to-floor with 10" treads
One US stair, finished floor to finished floor 9' 1 1/8" (109 1/8"), with 10" treads, in MeisterCalc's free stair calculator set to feet and inches, Rise only. It works in millimetres inside, so 109 1/8" is 109.125 × 25.4 = 2771.8 mm and 10" is 254 mm.
- Target riser: (600 − 254) ÷ 2 = 173 mm.
- Risers: 2771.8 ÷ 173 = 16.02, which rounds to 16 risers of 2771.8 ÷ 16 = 173.2 mm, or 6.82": shown as 6 13/16".
- Treads: 16 − 1 = 15, each 10".
- Total run (Rise only): 16 × 10" = 13' 4", which counts one tread's depth past the top riser onto the floor. The 15 treads take 12' 6".
- Stringer line: √(2771.8² + 4064²) = 4919.2 mm, 16' 1 11/16", at 34.30°.
- Stairwell opening, with a 12 1/2" floor (joists, subfloor and ceiling) and 6' 8" headroom: (12.5 + 80) × 10 ÷ 6.82 = 135.6", 11' 3 5/8".
Against the IRC limits the calculator quotes, riser 7 3/4" or less and tread 10" or more (City of Boise IRC handout, PDF), it passes, with the tread right on the minimum. All 16 risers are equal, so the 3/8" rule is met. Tick Riser Limited with a desired riser of 7 3/4" and you get fewer, taller steps: 15 risers of 7.275" (shown as 7 1/4"), 14 treads, 12' 6" of run in Rise only (the treads take 11' 8") and a 15' 5 1/2" stringer line at 36.04°.
The same stair in Calculator.net (Comprehensive, run 10 in, total rise 109.125 in, Fixed number of steps 15, standard mount; result read on 1 November 2026): Rise 6.82 inches (17.32 cm), Total Run 12 feet 6 inches (381.00 cm), Number of Steps 15, Stringer Length 15 feet 1.57 inches (461.18 cm), Stringer Height 8 feet 6.3 inches, Angle 34.30°. The rise, the run of the treads and the angle match ours.
With its headroom restriction on, floor thickness 12.5 in and headroom required 80 in, a 130 in floor opening returned “Headroom Requirement Not Met” (6 feet 4.16 inches of headroom), and a 136 in opening returned “Meets Headroom Requirement” (6 feet 10.98 inches) (Calculator.net). MeisterCalc's 135.6" opening sits between the two: one tool tests an opening you choose, the other tells you the length to frame.
Why the stringer lengths differ. Each step's diagonal is √(6.82² + 10²) = 12.10". Calculator.net's Stringer Height of 8' 6.3" is 15 rises (15 × 6.82 = 102.3"), so its stringer length covers 15 step diagonals: √(102.3² + 150²) = 181.6", its 15' 1.57" (Calculator.net). MeisterCalc's line runs 16 diagonals, up to the upper floor level: 16 × 12.10 = 193.7", or 16' 1 11/16". myCarpentry's figure is a third thing, the board length to buy (myCarpentry). Set the stringer out on the board before you cut, whichever you use.
Which IRC limits do these calculators use?
The same core figures: a riser of 7 3/4" or less, a tread of 10" or more and 6' 8" of headroom. They differ in what else they quote and where it comes from. Checked on 1 November 2026.
| Checked on 1 November 2026 | |||
|---|---|---|---|
| Limit | IRC, as the handouts MeisterCalc cites quote it | Calculator.net's page | myCarpentry's page |
| Riser height | 7 3/4" or less, R311.7.5.1 (Boise, PDF) | “maximum height of a riser be 7.75 inches” (source) | “should not exceed 7 3/4 inches” (source) |
| Risers in one flight | Within 3/8" of each other, R311.7.5.1 (Boise, PDF) | Not stated (source) | “should not vary more than 3/8 inch” (source) |
| Tread depth | 10" or more, R311.7.5.2 (Boise, PDF) | “a minimum length of 10 inches” (source) | “should not be less than 10 inches” (source) |
| Headroom | 6' 8", R311.7.2 (Knox County, PDF) | “at least 6 ft. 8 inches” (source) | “not be less than 6' 8"” (source) |
| Rise between landings | Not checked by MeisterCalc's calculator | Not stated (source) | “should not exceed 151 inches” (source) |
| Edition named | Section numbers as the City of Boise and Knox County handouts give them | None; “refer to the codes specific to their locations” (source) | 2024 IRC, Section R318 (source) |
US states and cities adopt the IRC with their own amendments, and some change these figures. Your building department decides what applies to your stair; no calculator makes a stair pass inspection.
Where is Calculator.net better?
- Both unit systems at once. Every result shows feet-inches and centimetres, for example “15 feet 1.57 inches or 461.18 cm”, and each input can be in its own unit (Calculator.net).
- A headroom warning. Enter the floor opening and it tells you whether the headroom is met (Calculator.net).
- Tread thickness, mount type and stringer placement. First step heights with and without the tread, standard or flush mount, and where the stringer sits (Calculator.net).
Where is myCarpentry better?
- It cites the IRC. It links the 2024 IRC, Section 318, quotes the riser, tread, variation, headroom, landing and open-riser rules, and flags results that may not meet them (myCarpentry).
- Figures ready to cut. The first step already has the tread thickness taken off, and the stringer length is the 2x12 you need (myCarpentry).
- Written by a carpenter. Its author describes himself as “a carpenter, programmer, and sole contributor” (myCarpentry), and a separate article covers landing heights (stairs and landings).
Where is MeisterCalc better?
- Four countries' rules. The free stair calculator checks the riser, going, 2R + G, pitch and headroom against the US IRC, Australia's NCC 2025, New Zealand's D1/AS1 or England's Approved Document K, with each limit's source.
- Riser Limited and Run only. Riser Limited rounds the count up so no riser is taller than your limit. Run only fits the treads to a fixed length; see fitting a stair into a fixed length.
- The opening to frame. It gives the stairwell opening length directly; the method is in how big a stairwell opening needs to be.
- Millimetres first, feet and inches on the same page, and an Android app where Stairs is free and every calculation runs on the phone.
Which free online stair calculator should you use?
Pick by the question you have. To test whether a floor opening gives enough headroom, Calculator.net answers it directly. To get the first-step cut and the stringer board length for a US stair, myCarpentry does. To size the opening, check the stair against your country's rules, or work in millimetres, use MeisterCalc's; and if you want it on the phone without a signal, Stairs in the app is free. For a stair with a landing, work out each flight on its own in any of them. For more on step counts, see how many steps a floor height needs.
What about Blocklayer?
Blocklayer's stair calculator draws and prints stringer templates and works out concrete stairs. It has its own page: Blocklayer compared with MeisterCalc.
Questions people ask
Does Calculator.net's number of steps count the risers?
Not in our test. With a 109 1/8" rise, 15 steps gave a rise of 6.82", which is 109.125 ÷ 16, so there were 16 rises (Calculator.net). Read the Rise figure to be sure.
Is there a myCarpentry app?
We found none on Google Play or the App Store on 1 November 2026. Its stair page says the old Mobile Stair Calculator “will be deprecated soon” and suggests using the page itself on a phone (myCarpentry).
Do these calculators check the building code?
In different ways. Calculator.net quotes general figures (Calculator.net); myCarpentry quotes the IRC and flags results (myCarpentry); MeisterCalc checks against the country you pick. None of them approves a stair: your building department does.
Can I use them in metric?
Yes. Calculator.net takes metres or centimetres in any field (Calculator.net), myCarpentry has a separate millimetres page (myCarpentry metric), and MeisterCalc starts in millimetres. To convert a total by hand, use the feet and inches calculator.
What are the limits of this comparison?
- Facts about Calculator.net and myCarpentry are what their own pages said on 1 November 2026. The Calculator.net results are what its page returned that day for the inputs given above; we did not run myCarpentry's calculator.
- The IRC figures are as the City of Boise and Knox County handouts quote them. Your state or city may amend them.
- Pages change. Check the calculator itself before you rely on a detail here.
Checked on 1 November 2026. Spotted something out of date? Write to meruappsdev@gmail.com.
Sources
- Calculator.net: Stair Calculator (versions, inputs, results for the example, code notes)
- myCarpentry: Stair Calculator, Stair Calculator Metric, Stairs and Landings and About the Carpenter
- City of Boise IRC handout 437, treads and risers (PDF) and Knox County stair guide (PDF), as cited in our stair calculator
- Google Play search and Apple's App Store search API (US), run on 1 November 2026
Stairs in MeisterCalc
Stairs (Home ▸ Stairs) has Rise Only, Rise + Run and Run Only modes, Riser Limited, and a live side view of the flight with the stairwell opening marked. For feet, inches and sixteenths, go to Settings ▸ Units ▸ Default units ▸ Imperial (ft/in). It is free, with Concrete and Check Square, and runs on Android 7.0 or later. The other 13 calculators unlock with a weekly subscription that starts with a 3-day free trial, or with a one-time lifetime unlock; Google Play shows the prices in your currency. See all the construction calculators.