Staircase Calculator

A convenient, highly accurate staircase calculator, stair layout tool, and baluster spacing calculator in one easy-to-use app.

Designed for professional contractors, carpenters, woodworkers, DIYers, and anyone installing stair balusters, spindles, deck railing, fence pickets, or other components requiring precise, uniform spacing.

ACCURATE STAIR & BALUSTER SPACING

Calculate the exact, even spacing required between balusters, spindles, posts, or pickets within a specific run.

Enter the length of the run, baluster width, and maximum spacing. The app calculates the layout and provides the measurements needed to mark your starting position and each subsequent baluster.

AUTOMATIC STAIR ANGLE MEASUREMENT

Your phone's built-in sensors can detect the slope or incline of your staircase.

Place your phone along the stair stringer or sloping surface and tap the arrow button. The measured angle transfers directly into the calculator, avoiding complicated geometric calculations.

Already know the angle? Enter it manually.

FULL US IMPERIAL SUPPORT

Designed for US construction measurements, including:

• Feet and inches
• Inches
• Fractions of an inch
• Decimal measurements

You can also switch to Metric units, including meters, centimeters, and millimeters.

MAIN FEATURES

• Accurate baluster and spindle spacing calculations
• Automatic stair slope and angle detection
• US Imperial and Metric measurements
• Inch and fractional-inch measurements
• Custom baluster or spindle widths
• Adjustable maximum spacing
• Detailed layout measurements
• Compensation for turned or shaped wooden balusters
• Fast recalculation when measurements change

HOW TO CALCULATE BALUSTER SPACING

1. Measure the diagonal run along the actual slope of the staircase, between the inside edges of the starting and finishing posts. Do not use the horizontal floor distance.

2. Measure the stair angle by placing your phone along the incline. Tap the arrow button to transfer the angle into the calculator, or enter a known angle manually.

3. Enter your baluster, spindle, or picket width.

4. Set your maximum permitted spacing.

5. Tap Calculate to see the required spacing and layout measurements from the starting post.

STAIR & RAILING CODE CONSIDERATIONS

For many residential applications in the United States, the commonly referenced IRC requirement is the 4-inch sphere rule, intended to prevent a 4-inch sphere from passing through openings in guards and stair railings.

The app uses a 3.75-inch default maximum spacing as a conservative starting point. Building codes vary by location, building type, and application, so always check the requirements applicable to your project and local building authority.

If the calculated spacing is awkward, adjust the maximum spacing and recalculate to find a clean, symmetrical layout.

MORE THAN A STAIR CALCULATOR

Use the app for:

• Interior staircases – wooden spindles, turned balusters, square balusters, and metal bars
• Deck railings – wood, composite, and other railing pickets
• Porches and guards – evenly spaced railing components
• Fences – fence pickets, garden fencing, and privacy screens
• General carpentry – any project requiring evenly spaced components

Whether you're a professional carpenter, contractor, stair installer, remodeler, woodworker, or DIY homeowner, this staircase calculator makes it easy to work out accurate baluster spacing, spindle spacing, stair railing spacing, and railing layouts.

Measure it. Enter it. Calculate it. Build it.