Turn a tapered-leg drawing into a jig setting. Enter the tapered length, the wide and narrow widths, and how many faces share the taper. The page returns the angle, the taper per foot, and how far to open the jig.
Use this when you are cutting tapered table or cabinet legs on a table saw with a hinged or adjustable taper jig and want the setting from the drawing rather than by trial cuts.
Measure the length of the tapered section (not the whole leg if the top stays square for the apron), the leg width where the taper starts, and the width you want at the foot. Decide whether the taper goes on one face of that dimension (typical for the inside faces of a table leg) or on both opposite faces.
The jig opening is given at a distance from the hinge you choose — some jigs have a scale at 12 in, others you measure with a ruler at the far end.
Each tapered face removes part of the width change. If only one face of the dimension is tapered, it removes all of it; if both opposite faces are tapered, each removes half. That per-face rise over the tapered length is the slope of the cut.
A hinged taper jig opens like a pair of scissors, so the gap at any distance from the hinge is that distance times the same slope. For opposite faces, the second cut is usually made with the already-tapered face against the jig, which tilts the leg by the first angle — so the second setting is twice the first.
rise per face = (W₁ − W₂) / faces
angle = atan(rise / L)
taper per foot = rise × 12 / L
jig opening at J = J × rise / L
opposite face (tapered face on the jig) = 2 × opening
Each row below starts from the default inputs and changes only the columns shown. Recompute any row by hand with the formula above.
| L | W₁ | W₂ | Faces | At | Angle | In/ft | Opening | 2nd face |
|---|---|---|---|---|---|---|---|---|
| 24 | 1.75 | 1 | 2 | 24 | 0.895° | 0.1875 | 0.3750 | 0.7500 |
| 24 | 1.75 | 1 | 1 | 24 | 1.790° | 0.3750 | 0.7500 | — |
| 24 | 1.75 | 1 | 2 | 12 | 0.895° | 0.1875 | 0.1875 | 0.3750 |
| 28 | 2.5 | 1.5 | 2 | 24 | 1.023° | 0.2143 | 0.4286 | 0.8571 |
| 18 | 1.5 | 0.875 | 1 | 12 | 1.989° | 0.4167 | 0.4167 | — |
With the calculator defaults (Tapered length (in) = 24; Measure jig opening at (in) = 24; Width at start of taper (in) = 1.75; Width at the foot (in) = 1; Faces tapered in this direction = 2), the arithmetic runs like this:
rise per face = (W₁ − W₂) / faces = (1.75 − 1) / 2 = 0.3750 in
angle = atan(rise / L) = atan(0.3750 / 24) = 0.895°
taper per foot = rise × 12 / L = 0.1875 in/ft
jig opening at 24 in = 24 × 0.3750 / 24 = 0.3750 in
opposite face, tapered face riding the jig: 2 × 0.3750 = 0.7500 in
Result: 0.3750 in jig opening. Angle 0.895° per face, 0.1875 in per foot. About 3/8 in on a tape. Second (opposite) face: 0.7500 in if the first tapered face rides against the jig.
Now change Faces tapered in this direction to 1 and leave everything else alone:
rise per face = (W₁ − W₂) / faces = (1.75 − 1) / 1 = 0.7500 in
angle = atan(rise / L) = atan(0.7500 / 24) = 1.790°
taper per foot = rise × 12 / L = 0.3750 in/ft
jig opening at 24 in = 24 × 0.7500 / 24 = 0.7500 in
Result: 0.7500 in jig opening. Angle 1.790° per face, 0.3750 in per foot. About 3/4 in on a tape.
Putting the whole taper on one face doubles the per-face rise and the jig opening, but there is no second cut to set. That is the usual choice for the two inside faces of a table leg, where the outside faces stay straight.
Mark the taper on the first leg with a pencil and a straightedge before you cut. Set the jig from this page, then lay the leg on the jig against the blade with the saw off and check that the blade lines up with the pencil line at both ends. That catches a reversed leg or a measurement taken from the wrong end.
Start the taper a little below the apron line so the joint stays square. If the drawing says the taper starts 5 in from the top of a 29 in leg, the tapered length is 24 in, not 29 in.
Tapers on two adjacent faces (the inside faces of a table leg) are each cut with untapered faces against the jig, so both use the first setting. Only an opposite face that rides on an already-cut taper needs the doubled setting.
Units: Inches throughout. Angles in degrees.
Where the model stops: It assumes a straight taper from start to foot and a jig whose gap opens in proportion to distance from the hinge. Jigs with a fixed-angle scale should be set by angle instead.
Not a substitute: Use the jig maker’s instructions, hold-downs, and a push block. Keep hands clear of the blade; this page only does the geometry.
After the first cut, the tapered face is no longer parallel to the leg’s centerline. When it rides against the jig, the leg is already tilted by the first angle, so the jig must open twice as far to cut the matching taper on the far side.
Use the taper-per-foot output. A rise of 0.375 in over 24 in is 0.1875 in per foot.
No — only the distance from the hinge to where you measure the gap. Measure at the same point every time.
Yes. Run the page once for each direction of the leg with 2 faces selected, and use the doubled setting for each opposite face.