Morse Taper Dimensions Chart (MT0 to MT7): Gauge Line, Angle & TPF Calculator
Standard Morse Tapers (MT0 through MT7) governed by ISO 296, DIN 228, and ASME B5.10 are self-holding conical machine tool shanks with a nominal taper ratio of approximately 1:20 (~0.600 in/ft TPF, ~1° 26' half-angle). Their exact gauge-line diameters (D_1) are MT1 = 12.065 mm (0.475"), MT2 = 17.780 mm (0.700"), MT3 = 23.825 mm (0.938"), MT4 = 31.267 mm (1.231"), and MT5 = 44.399 mm (1.748").
Morse Taper Dimensions & Gauge Line Calculator (MT0 to MT7)
Lookup exact ISO 296 / DIN 228 / ASME B5.10 Morse taper gauge line diameter (D_1), small end (d), socket depth (l), drawbar thread, and half-angle (α).
How Do You Identify a Morse Taper Size (MT1, MT2, MT3, MT4, MT5) with Calipers?
Every machine shop houses dozens of taper-shank twist drills, lathe live centers, drill chuck arbors, and reducing sleeves whose stamped size markings have worn off over years of service. Under ISO International Metrology Standard (ISO 296 Self-Holding Tapers) and ASME Geometric & Mechanical Standards (ASME B5.10), the definitive way to identify any Morse taper in 5 seconds is to measure the Gauge-Line Diameter (D_1)—the diameter of the conical shank right at the mouth of the female spindle socket (or about 2 to 5 mm back from the large shoulder of the male arbor)—using a digital vernier caliper.
If the large end of the cone measures just under 1/2" (12.065 mm / 0.4750"), it is an MT1; if it measures 0.7000" (17.780 mm), it is an MT2 (the standard tailstock taper on 10"–14" bench and toolroom lathes); if it measures 15/16" (23.825 mm / 0.9380"), it is an MT3; if it measures 1-15/64" (31.267 mm / 1.2310"), it is an MT4; and if it measures 1-3/4" (44.399 mm / 1.7480"), it is an MT5. Simply type your caliper measurement into the interactive identifier box above to lock in the exact standard match.
| Morse Taper Size | Gauge Line Dia D_1 (Large End) | Small End Dia d (Tang Neck) | Socket Depth l (Tanged Shank) | Taper Per Foot (TPF, in/ft) | Taper Ratio (1 : X) | Centerline Half-Angle (α) |
|---|---|---|---|---|---|---|
| MT0 | 9.045 mm (0.3561") | 6.401 mm (0.2520") | 50.8 mm (2.000") | 0.6246 in/ft | 1 : 19.212 | 1° 29' 27" (1.4908°) |
| MT1 | 12.065 mm (0.4750") | 9.373 mm (0.3690") | 54.0 mm (2.125") | 0.5986 in/ft | 1 : 20.047 | 1° 25' 43" (1.4286°) |
| MT2 | 17.780 mm (0.7000") | 14.580 mm (0.5740") | 64.0 mm (2.519") | 0.5994 in/ft | 1 : 20.020 | 1° 25' 50" (1.4307°) |
| MT3 | 23.825 mm (0.9380") | 19.792 mm (0.7792") | 80.2 mm (3.156") | 0.6024 in/ft | 1 : 19.922 | 1° 26' 16" (1.4378°) |
| MT4 | 31.267 mm (1.2310") | 25.908 mm (1.0200") | 102.5 mm (4.031") | 0.6233 in/ft | 1 : 19.254 | 1° 29' 15" (1.4876°) |
| MT5 | 44.399 mm (1.7480") | 37.592 mm (1.4800") | 129.5 mm (5.100") | 0.6315 in/ft | 1 : 19.002 | 1° 30' 26" (1.5074°) |
| MT6 | 63.348 mm (2.4940") | 53.848 mm (2.1200") | 182.0 mm (7.165") | 0.6256 in/ft | 1 : 19.180 | 1° 29' 36" (1.4933°) |
| MT7 | 83.058 mm (3.2700") | 72.085 mm (2.8380") | 254.0 mm (10.000") | 0.6000 in/ft | 1 : 20.000 | 1° 25' 56" (1.4321°) |
Why Each Morse Taper Size Has a Slightly Different Taper Angle and TPF
Unlike the later Jarno taper system (which was mathematically defined at an exact 1:20 ratio or 0.6000 in/ft across all sizes), Stephen A. Morse developed the original Morse taper gauges in 1864 in New Bedford, Massachusetts, by empirically fitting twist-drill shanks before standardized optical goniometers existed. When ANSI Engineering Standards Webstore and Machinery's Handbook (Industrial Press) later codified the existing industrial master plugs so millions of legacy machines would remain interchangeable, they preserved the exact historical angles of each size.
Consequently, if you are single-point turning or cylindrical grinding a replacement Morse taper arbor on a lathe, never assume all Morse tapers are 1.432°! Specifically, MT1 has a half-angle of 1.4286° (0.5986 in/ft), MT2 is 1.4307° (0.5994 in/ft), MT3 is 1.4378° (0.6024 in/ft), MT4 jumps to 1.4876° (0.6233 in/ft), and MT5 is 1.5074° (0.6315 in/ft). Because a self-holding taper relies on >85% Prussian-blue contact area for frictional torque transmission, an angular error of just 0.05° causes the arbor to rock and spin inside the spindle socket.
| Morse Taper Size | Max Tang Thickness (c) | Spindle Drift Slot Width × Length | DIN 228 Form A Metric Drawbar Thread | ANSI B5.10 Inch Drawbar Thread | Typical Shop Application |
|---|---|---|---|---|---|
| MT1 | 5.2 mm (0.203") | 5.5 × 19.0 mm (0.219" × 0.75") | M6 × 1.0 | 1/4"-20 UNC | Small sensitive drill presses, mini-lathe tailstocks |
| MT2 | 6.5 mm (0.250") | 7.0 × 22.0 mm (0.281" × 0.88") | M10 × 1.5 | 3/8"-16 UNC | Benchtop mills, 12"–14" engine lathe live centers, Ø14–23 mm drills |
| MT3 | 8.0 mm (0.312") | 8.5 × 27.0 mm (0.344" × 1.06") | M12 × 1.75 | 1/2"-13 UNC | Geared-head drill presses, 16" lathe tailstocks, Ø23.5–31.75 mm drills |
| MT4 | 11.9 mm (0.469") | 12.5 × 32.0 mm (0.500" × 1.25") | M16 × 2.0 | 5/8"-11 UNC | Radial arm drills, heavy turret lathes, Ø32–50 mm taper-shank drills |
| MT5 | 15.9 mm (0.625") | 16.5 × 38.0 mm (0.656" × 1.50") | M20 × 2.5 | 3/4"-10 UNC | Heavy oilfield lathes, boring mills, Ø50.5–75 mm twist drills |
| MT6 | 19.0 mm (0.750") | 20.0 × 44.0 mm (0.781" × 1.75") | M24 × 3.0 | 1"-8 UNC | Large floor-type horizontal boring mills and heavy shipyard lathes |
DIN 228 Form A (Tapped Drawbar) vs Form B (Flat Ejection Tang) Shanks
Under DIN 228 Part 1 and NIST (National Institute of Standards and Technology) workshop safety rules, Morse taper shanks are manufactured in two distinct rear-end configurations that must never be confused on a milling machine: Form B (Tanged Shank) features a flat paddle tang at the small end designed to engage the drift slot of a drill press quill or lathe tailstock for wedge ejection, whereas Form A (Tapped Shank) features a precision female thread (such as M10 or 3/8"-16 on MT2, and M12 or 1/2"-13 on MT3) for a through-spindle retention drawbar. Never side-mill with an un-drawn Form B tanged arbor—lateral cutter vibration will break the friction lock and drop the spinning cutter out of the spindle! Cross-check your lathe compound angle setup on our Lathe Taper Per Foot (TPF) to Degrees Calculator, verify sine-bar grinding heights on our Sine Bar Gage Block Calculator, check drawbar thread limits on our ASME B1.1 Thread Class Calculator, and size drill shanks on our Drill Bit Size Converter.