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Morse Taper Dimensions Chart

Guide · Updated October 28, 2026

Morse tapers are self-holding tapers used on drill shanks, lathe tailstocks and headstock spindles, and drill press spindles. They are about 5/8 in per foot, but each number has its own slightly different taper, so a reamer or sleeve must match the number. The table gives the diameter at the gage line (the large end of the socket), the small end of the plug, the taper per foot and the plug depth from Machinery’s Handbook Table 1b, Morse Standard Taper Shanks.

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Step by step

  1. Measure the large end: Mic the shank at the large end of the taper, near where it would enter the socket.
  2. Measure the length: Measure the tapered length from the large end to the small end.
  3. Measure the small end: Mic the small end.
  4. Find the number: Match the large end to the chart; diameters are far enough apart to identify the number.
  5. Check the taper: Taper per foot = (large − small) ÷ length × 12, and compare with the chart.
  6. Check the fit: Blue the shank and twist it in the socket; contact should run the full length.

Morse taper chart (inches)

Taper per inch is the taper per foot ÷ 12: MT2 is 0.04995 in/in and MT3 is 0.05019 in/in. Metric equivalents of the gage diameters are 9.045, 12.065, 17.780, 23.825, 31.267, 44.399 and 63.348 mm for MT0 to MT6 (ISO 296).

Half angle for setting the compound

Half angle = arctan(taper per foot ÷ 24). MT1: 1.4287°, MT2: 1.4307°, MT3: 1.4377°, MT4: 1.4876°, MT5: 1.5073°. Most shops call it 1°29’ or about 1.43° to 1.49°, but the compound cannot be set that closely from the scale, so set it with an indicator travel or a test bar.

Worked example: identify a shank

A drill shank measures 0.935 in near the large end and 0.785 in at the small end over 3.0 in of length. The large end matches MT3 (0.938). Taper per foot = (0.935 − 0.785) ÷ 3.0 × 12 = 0.600 in/ft, close to the MT3 value of 0.602. It is MT3.

Worked example: set the compound by indicator

For MT2, taper per inch on diameter is 0.04995, so per side it is 0.02498 in per inch. Set an indicator on the compound slide against an MT2 test bar or a known good shank; move the carriage 1.000 in and adjust the compound until the indicator changes 0.0250 in. Over 2 in of travel, look for 0.0500 in. A 0.001 in error over 2 in changes the fit enough to show up in bluing.

Tangs, drifts and stub tapers

Drill shanks have a tang that fits a slot in the socket so a drift can knock the tool out; the tang is not meant to drive the drill. Lathe spindles and tailstocks often use tangless shanks with a draw bar or rely on friction. Morse stub tapers are shorter versions with the same tapers, used where length is limited.

Common problems

Using a Brown and Sharpe or Jarno taper reamer on a Morse socket, setting the compound from the scale only, dirty or burred sockets that let the tool spin, and assuming every MT number is exactly 5/8 in per foot. Clean the socket, stone burrs and check fit with bluing.

FAQ

What is the taper per foot of MT2?

0.59941 in/ft, about 1.43 degrees half angle.

What is the large end diameter of an MT3?

0.938 in at the gage line.

Are all Morse tapers the same angle?

No, they range from 0.59858 in/ft (MT1) to 0.63151 in/ft (MT5).

How do I check a taper?

Check the gage itself before trusting a measurement: gage blocks set mics, calipers and indicators; build any stack free at gageblockcalc.com.

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General shop information only — follow your drawing, tool maker's data and your quality system.