Dovetail Spacing Calculator — Joint Layout

Use 1:6 for softwoods (steeper angle for better grip in softer fibres) and 1:8 for hardwoods (shallower angle to prevent short grain breakout). 1:7 is a good general-purpose compromise. The ratio describes the rise to run of the tail angle.

Pin width is a matter of style. Fine pins (London pattern) are narrow and decorative. Equal pins and tails look balanced. Traditional tails are wider than pins for maximum mechanical strength. Fine pins are typically 3-5mm at the narrow end.

Half pins are narrow pins at each edge of the board. They prevent the joint from opening at the edges under stress and stop the end grain of the corner tail from being exposed. Fine Woodworking sizes half-pins to about 6–9.5mm (1/4–3/8in) at the narrow end — an absolute dimension, not a fixed fraction of the board thickness — so the edge pins stay neat even on thick stock.

Through dovetails are visible from both sides and are the strongest. Half-blind dovetails are hidden from the front, used in drawer construction where you want a clean face. Sliding dovetails are used for shelves and dividers in a housing channel.