Stair Handrail Length

Finds the slope distance between nosings by Pythagoras — the run is tread × (steps − 1), the rise is riser × steps — then adds a fixed margin for the end fittings.

Your numbers

Number of steps()Riser height(cm)Tread depth(cm)End allowance(cm)

Handrail length

4.73m

Slope distance

4.43m

Formula

Handrail length = √((Tread depth×(Number of steps-1))² + (Riser height×Number of steps)²) ÷ 100 + End allowance÷100

If your baluster spacing is fixed by code, divide this length by that spacing first to plan how many you need.

What to enter

Input	Default	Accepted range
Number of steps	14	1 ~ 60
Riser height (cm)	18	5 ~ 30
Tread depth (cm)	28	15 ~ 50
End allowance (cm)	30	0 ~ 100

Step by step

FormulaHandrail length = √((Tread depth×(Number of steps-1))² + (Riser height×Number of steps)²) ÷ 100 + End allowance÷100

With the default numbersHandrail length = √((28×(14-1))² + (18×14)²) ÷ 100 + 30÷100

AnswerHandrail length = 4.73 m

Quick reference table

Results when only Number of steps changes and everything else stays put.

Number of steps	Handrail length (m)	Slope distance (m)
7	2.4	2.1
10.5	3.56	3.26
14	4.73	4.43
21	7.06	6.76
28	9.39	9.09

What each result means

Result	At default values
Handrail length (m)The slope distance plus a margin for the end fittings — what you actually order.	4.73
Slope distance (m)The slope distance between nosings, found by Pythagoras from the run and rise.	4.43

Common mistakes

If your baluster spacing is fixed by code, divide this length by that spacing first to plan how many you need.

Glossary

Handrail length: The slope distance plus a margin for the end fittings — what you actually order.
Slope distance: The slope distance between nosings, found by Pythagoras from the run and rise.

Frequently asked questions

QHow is Stair Handrail Length calculated?

Handrail length = √((Tread depth×(Number of steps-1))² + (Riser height×Number of steps)²) ÷ 100 + End allowance÷100 — Finds the slope distance between nosings by Pythagoras — the run is tread × (steps − 1), the rise is riser × steps — then adds a fixed margin for the end fittings.

QCan you walk through an example?

With Number of steps 14, Riser height 18cm, Tread depth 28cm, End allowance 30cm, the answer is Handrail length 4.73m.

QWhat do I need to enter?

Enter Number of steps, Riser height, Tread depth, End allowance. The result recalculates as you type, and an empty box counts as zero.

QHow much does the answer move if I change a number?

Changing only Number of steps moves the answer to Number of steps 7 → Handrail length (m) 2.4 and Number of steps 28 → Handrail length (m) 9.39. The table below lays out five steps.

QHow are the numbers rounded?

Money is shown to the nearest whole unit, percentages to one decimal place and everything else to two. What you see is rounded; the calculation itself carries the unrounded value forward.

QAnything to watch out for?

If your baluster spacing is fixed by code, divide this length by that spacing first to plan how many you need.

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Keep your length units consistent across inputs — mixing centimetres and metres throws results far off.