Circular Stairs Calculator
Arc Length =
Used to find the Angle, Chord and Arc Length when Radius is known.
Enter Radius then Angle, Chord and Arc Length are calculated. Change Chord then Angle and Arc Length are re-calculate. Change Arc Length then Angle and Chord will re-calculate.
Arc Length will sometimes equal the Chord. This is because they are so close in value that they fall within the same precision which is set to ¹/₆₄.
To change precision select ([icon--app-more]) in upper right corner, then select Settings.
Laying out circular stairs.
A plan calls for a curved section of stairs. The Radius is 90 inches and the Angle is 45°. The Chord and Arc Length are calculated and displayed.
Radius = 90in or 7ft 6in
Angle = 45
Chord = 5ft 8&7/8in
Arc Length = 5ft 10&11/16in
To calculate the Chord for the individual treads select the Arc Length, then select the calculator icon. Click on the Arc Length at top of the screen. Now divide it by the number of treads (in this case 6), then click done. The individual Angle, Chord , and Arc Length are re-calculated and displayed.
Angle = 7.5001766932
Chord = 11&49/64in
Arc Length 11&25/32in