Dovetail Layout Calculator
Half pins stop the end tail splitting off.
Work out Dovetail Layout. Half pins stop the end tail splitting off. Counts the thing everyone forgets to count.
Tail width
31.5 mm
4 tails, 3 pins, 1:8 slope (7.13°)
The slope is conventionally 1:8 for hardwood and 1:6 for softwood, and the reason is grain strength: a steeper slope leaves more short grain at the tip of the tail, which softwood can afford and hardwood need not. Half pins at each end are not decoration. They are what stops the outermost tail from splitting the end of the board, and they are the only pins present on a single-tail joint. Pin width is a style decision with a practical floor. Fine London-pattern pins look superb and leave almost nothing to saw to — a beginner is far better served by pins roughly a third of the tail width.
How the Dovetail Layout Calculator works
Tail and pin spacing from board width, thickness and tail count, with marking positions from the edge and the flare on the wide face. Slopes from 1:6 for softwood to 1:10 for fine hardwood.
Also known as: how to space dovetails · dovetail angle 1:8 · dovetail marking out · how many tails for a drawer
Frequently asked questions
What dovetail angle should I use?
1:8 for hardwood and 1:6 for softwood. A steeper slope leaves more short grain at the tail tip, which softwood can afford and hardwood does not need.
What is a half pin?
The narrower pin at each end of the joint. It is structural, not decorative — it stops the outermost tail from splitting the end of the board, and a single-tail joint has nothing but half pins.
How many tails should I cut?
Roughly one every 25 to 40 mm of board width is a common starting point. More tails is more work and more strength; fewer looks bolder and is faster.
Should pins be narrower than tails?
By convention in hand-cut work, yes — often a third of the tail width or less. Machine jigs cut them equal, which is the quickest way to tell the two apart from across a room.
Why is the pin wider on one face?
Because the slope flares it. The wide face is the narrow width plus twice the thickness divided by the slope ratio, which is why thick stock produces such visibly tapered pins.
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