Balustrade Calculator
Calculate baluster count for 99mm max gap compliance (Part K sphere test), handrail length, newel height and base rail.
Total run of balustrade
Top and bottom of each flight
Full height from floor
How We Calculate This
This calculator determines the number of balusters to achieve a maximum 100mm gap (Part K compliance), plus handrail length, base rail and newel post quantities.
The formula
Balusters = Length ÷ (Baluster width + Max gap)
Actual gap = (Length ÷ Balusters) - Baluster width
Handrail length = Total balustrade run
Must satisfy: Gap < 100mm (100mm sphere must not pass through)
Part K requirements
- 99mm max clear gap (100mm sphere must not pass through)
- Handrail 900-1000mm on stairs and internal landings, 1100mm on external balconies
- Balustrade must resist 0.36 kN/m horizontal loading
- No climbable features below 600mm height
Frequently Asked Questions
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Last updated: March 2026
All calculations are estimates. Verify with your supplier.