Dovetail Angle Calculator

The dovetail angle (slope ratio) determines how much the tails flare out. The correct angle balances mechanical strength (more flare = harder to pull apart) against structural integrity (too much flare = short grain that can split).

Traditional dovetail angles:

• Hardwood (oak, maple, cherry, walnut): 1:8 (7.1°): less flare, strong grain
• Softwood (pine, cedar, spruce): 1:6 (9.5°): more flare, weaker grain needs more mechanical lock
• Variation: Anywhere from 1:5 (11.3°) to 1:10 (5.7°) will work

Slope formula: Slope angle = arctan(1 / ratio) Example: 1:8 ratio → arctan(0.125) = 7.125°

How to set a sliding bevel: The ratio notation (1:6, 1:8) tells you how to set the bevel physically:

• Mark 1 unit across the baseline
• Mark the ratio number (6 or 8) along the direction of cut
• Set your bevel to connect these two marks

Proportions of pins to tails: There is no single correct proportion, but common ratios are:

• Fine furniture: thin pins (1/3 of tail width), many tails
• Utility boxes: equal pins and tails
• Rustic / structural: thick pins, fewer tails

Half-blind dovetails (used for drawer fronts) are typically set to 1:6–1:7 to give more mechanical resistance since only the tails are hidden. The dropdown pairs half-blind with 1:7 for that reason. An earlier version of this page offered it at 1:5, which is a softwood angle and more flare than a half-blind joint wants.

Which way round the ratio runs

This is the bit that gets stated backwards more often than not, including in places that ought to know better, so it is worth being blunt about it.

A bigger second number means LESS flare. 1:10 is the shallowest angle on the page at 5.7°, and 1:5 is the steepest at 11.3°. The ratio is rise over run, so a run of 10 for a rise of 1 is a gentler slope than a run of 5.

Which means hardwoods take the high numbers and softwoods the low ones. Hardwood has long, tough grain that holds a joint together on its own, so it does not need much mechanical lock and a steep flare would only create fragile short grain at the tail corners. Softwood is the opposite: weaker grain, so more flare to make the joint hold mechanically, and the short grain it creates is less of a liability in a wood that was never going to hold on grain strength alone.

Anything from 1:5 to 1:10 cuts and holds. The traditional pairing is 1:8 for hardwood and 1:6 for softwood, and honestly, plenty of fine work has been done at whatever angle the maker’s bevel happened to be set to.