Size a stair or a ramp from the rise
Type the floor to floor height, get the number of risers, their height, the run and whether the stair is comfortable. Switch to a ramp for the length at a given slope.
Sizing a stair early
A stair is set by its rise. Divide the floor to floor height into equal risers and the rest follows: how many treads, how deep each one, how long the run and how much of the plan it takes. Getting that right in the first sketch saves a redesign later.
The calculator rounds to a whole number of risers, which is the one thing a stair cannot fudge, and reports the comfort line, two risers plus a tread between 600 and 650 millimetres, that most people find natural to climb.
Codes set hard limits on riser height, tread depth, headroom and handrails, and they differ by country and by building type. Use the result to lay out the stair, then check the code that applies before drawing it.
Ramps are set by slope. An accessible ramp is usually 1 in 12 or gentler, with a level landing every 9 meters of run and at every change of direction. The calculator gives the length and the number of landings for the slope you pick.
Other free tools
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- File Size EstimatorEstimate image file size from pixel dimensions and format, JPEG, WebP, PNG or TIFF, and check whether it fits an email. Free, no sign up.
The numbers are done. Now the image.
Turn the sketch, plan or model into a render the client can react to.