Baluster Spacing Calculator

Space balusters perfectly on any deck, porch or stair railing. Enter the space between your posts and your baluster width, and get the number of balusters, the exact gap and every mark to make on the rail.

The result updates as you type. No Calculate button, no account, no ads.

WHAT IT DOES
• Equal spacing: the fewest balusters that keep every gap under the limit, spaced evenly
• Fixed gap: set the gap you want and get equal end gaps at both posts
• Stair railings at any angle: enter rise and run (or the angle) and measure the span along the rail
• Code check: a green or red result against the 4" sphere rule (4-3/8" on stairs), with the rule shown
• Marks measured from the post face, to the baluster edge or centre
• Inches with fractions to 1/16" (or 1/8"), or millimetres
• Drawing to scale of the whole run
• Even spacing calculator for siding, board and batten, panels and shelves
• Works offline, no limits on span or angle

BUILDING CODE PRESETS
US (IRC), California, Canada, UK (Approved Document K) and Australia. Openings of 4", 100 mm or 125 mm, depending on your region. You can also turn the code check off.

PRO: ONE PAYMENT, NO SUBSCRIPTION
• Saved projects with several runs, for example the three sides of a deck
• Material list: total balusters across all runs, plus 5, 10 or 15 % spares
• Voice readout: the app reads each mark aloud; step with the volume keys and keep your hands on the tape
• Share the layout as an image or PDF, with the drawing and every mark

The calculator itself is free and complete. Pro just saves time if you build railings often.

Made for DIY homeowners building or fixing a deck railing, and for carpenters and railing installers who do it every week.

Always check your local building code before you build.

Recent changes:
Enabled code shrinking and obfuscation to make the app smaller and faster, and to meet Google Play's DEX optimization requirements.