Dovetail Layout Calculator
A dovetail joint is one of the strongest and most attractive joints in hand woodworking. Laying out tails and pins evenly across a board requires dividing the available width to accommodate half-pins at each edge and full tails between them, with pins filling the gaps between tails. This calculator takes the board width, the number of tails, and the tail-to-pin width ratio, then computes the centre-to-centre spacing, the tail width, the pin width, and all the layout marks from the left edge. The layout uses the standard convention of a half-pin at each edge, with all tails and interior pins equally spaced.
Dovetail layout formula
Unit = board width / (tails × ratio + (tails - 1) + ratio)
Pin width = unit
Tail width = unit × ratio
Half-pin = unit / 2
Pitch = tail width + pin width
The layout divides the board into segments: two half-pins at the edges, (tails - 1) full pins between tails, and n tails. Solving for the unit width that satisfies these constraints gives the dimensions above. The pitch is the centre-to-centre distance between adjacent tail centres.
Laying out dovetails by hand
- Mark the baseline (thickness of the mating board) with a marking gauge on all four faces.
- Divide the board width into equal segments using the divider method or the calculator output above.
- Mark tails first (tails board), then use them as a template to scribe the pins (pins board).
- Cut the tails with a fine-tooth saw such as a Japanese ryoba or a Western dovetail saw, staying on the waste side of the line.
- Chop out the waste between tails with a sharp chisel, working from both faces to the baseline.
Dovetail layout calculator: frequently asked questions
What is the traditional dovetail ratio for hardwoods?
The standard dovetail angle for hardwoods is 1:8 (about 7 degrees), meaning 1 unit of rise for every 8 units of run. For softwoods a gentler 1:6 ratio (about 9.5 degrees) is used. These ratios balance strength with resistance to splitting along the grain.
How many tails should a dovetail joint have?
The number of tails depends on board width and personal aesthetics. A common approach is to use one tail per inch of board width, or to size tails so they are roughly twice the width of the pins. Most hand-cut dovetails use an odd number of tails.
What are half-pin tails at the edges?
Traditionally the outermost elements of a dovetail joint are half-pins (pins at each edge of the board). This calculator places a half-pin at each edge and distributes full tails evenly between them, matching the most common hand-cut layout.
What is the difference between through dovetails and half-blind dovetails?
Through dovetails are cut all the way through the board and are visible on the end grain of both pieces. Half-blind dovetails leave a thin wall of wood on the show face, hiding the joint. Both use the same spacing formula; only the depth differs.
Can I use this calculator for drawer making?
Yes. Drawers typically use half-blind dovetails at the front and through dovetails at the back. Enter the drawer-front or side width to get the tail and pin spacing for either location.
Official sources
- USDA Forest Products Laboratory: Wood Handbook, FPL-GTR-190 (joint design principles).
- USDA Forest Service: FPL Homepage.
Reviewed by the CalculatorHub team, edited by James Graham, 15 June 2026. See our methodology.