The calculation uses the arctangent function to find the angle from the sides of a right-angled triangle.

1. Determine Triangle Sides: Imagine a right-angled triangle where the 'adjacent' side is the length of your drawer side, and the 'opposite' side is the difference between your tallest and shortest heights.
2. Calculate Height Difference: The calculator finds the length of the 'opposite' side by subtracting the shortest height from the tallest height.
3. Apply Arctangent: The angle is found by calculating the arctangent of the ratio of the opposite side to the adjacent side. The result is then converted from radians to degrees.
   Angle = arctan( (Height Difference) / Length )

Example 1: A classic tapered drawer side.
Tall end 6″, short end 4″ over an 18″ side. The height difference is 2″, so the taper angle is arctan(2 ÷ 18) ≈ 6.34°. On a tapering jig you set that 6.34°; on a miter gauge you'd instead dial in 90 − 6.34 = 83.66°.

Example 2: A gently tapered table leg.
A leg that's 2.5″ at the top and 1.5″ at the bottom over 30″ has a 1″ difference, giving arctan(1 ÷ 30) ≈ 1.9°. Small angles like this are exactly where a jig beats eyeballing the fence offset.

• Setting the miter gauge to the taper angle. The result is the taper itself, not the gauge reading. Subtract it from 90° to get the miter-gauge angle, or you'll cut a taper many times too steep.
• Tapering both faces from one number. A leg tapers on more than one side; each cut removes its own wedge. Re-measure the height difference for each face instead of assuming one angle finishes the leg.
• Using the diagonal, not the length. Feed the horizontal run (the length of the side) into the calculator, not the slanted top-to-bottom distance, or the angle comes out short.
• Forgetting grain direction on legs. A taper cut across a weak grain line can chip or flex; orient the taper so the strong grain runs with the cut.

"For drawer sides I aim for the taper that lets the front sit proud and the back tuck under the runners — often a couple of degrees. I calculate it once, set a stop and the jig, and every side in the set matches without chasing fit at the bench." — Furniture Builder

"Cut just shy of the line and clean up with a plane. On a taper, a hair of extra material is invisible and adjustable, but a cut gone too far means a new part. Let the number on this page be your target, not your first pass."

• Taper: A gradual narrowing of an object from one end to the other.
• Tapering Jig: A table saw jig that holds a workpiece at a specific angle to the blade, allowing for the creation of tapered cuts.
• Arctangent (arctan): A trigonometric function that calculates the angle of a right-angled triangle from the ratio of its opposite and adjacent sides.