Dovetail Spacing Calculator
Enter geometric parameters to see tail width, gap width, and layout marks in the same units.
A geometry diagram aid only. It does not provide woodworking safety or tool guidance.
A QUICK WALKTHROUGH
How to use this tool
- Enter the board width.
- Set the tail count and tail-to-gap ratio.
- Review the calculated geometric layout.
Simple geometric model
The calculator divides the width into the selected number of equal tails and the gaps between them. The ratio controls gap width relative to tail width.
Marks are measurements
Positions are measured from the left edge in the same units as board width. This is a layout diagram aid and does not model slope angles, end margins, kerfs, or joinery tolerances.
Local processing
Calculations happen in this browser. No measurements are uploaded or stored.
GOOD TO KNOW
Common questions
What does the ratio mean?
A ratio of 1 means each gap is the same width as a tail; 0.5 means each gap is half a tail width.
Does this design a complete joint?
No. It only calculates a simple width distribution and mark positions.
Are units converted?
No. Use one consistent unit; the output keeps that unit implicitly.