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Brown & Sharpe and Jarno Taper Chart

Guide · Updated October 28, 2026

Brown & Sharpe and Jarno tapers are older self-holding tapers still found on grinder spindles, dividing heads, older milling machines, lathe headstocks and watchmaker and jeweler tooling. Brown & Sharpe tapers run close to 0.500 in per foot; Jarno tapers are exactly 0.600 in per foot with a simple naming rule. Dimensions below follow the published B&S table (Machinery's Handbook values as reproduced in the Wikipedia machine taper article); Jarno values come straight from the Jarno rule.

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Step by step

Measure the large end: Mic the shank at the gauge end or the socket mouth.
Measure the small end: Mic the small end and measure the cone length.
Compute taper per foot: (Large − small) ÷ length × 12.
Classify: About 0.50 in/ft is Brown & Sharpe, 0.60 is Jarno, about 0.62 is Morse.
Match the size: Find the row whose large end matches within a few tenths.
Confirm with bluing: Blue the shank and twist in the socket; full-length contact confirms the match.

Brown & Sharpe taper dimensions

B&S No. 1: large end 0.2392 in, small end 0.2000 in, length 0.94 in
B&S No. 2: large end 0.2997 in, small end 0.2500 in, length 1.19 in
B&S No. 3: large end 0.3753 in, small end 0.3125 in, length 1.50 in
B&S No. 4: large end 0.4207 in, small end 0.3500 in, length 1.69 in
B&S No. 5: large end 0.5388 in, small end 0.4500 in, length 2.13 in
B&S No. 6: large end 0.5996 in, small end 0.5000 in, length 2.38 in
B&S No. 7: large end 0.7201 in, small end 0.6000 in, length 2.88 in
B&S No. 8: large end 0.8987 in, small end 0.7500 in, length 3.56 in
B&S No. 9: large end 1.0775 in, small end 0.9001 in, length 4.25 in
B&S No. 10: large end 1.2597 in, small end 1.0447 in, length 5.00 in
B&S No. 11: large end 1.4978 in, small end 1.2500 in, length 5.94 in
B&S No. 12: large end 1.7968 in, small end 1.5001 in, length 7.13 in

Taper per foot is 0.500 to 0.502 in/ft for most sizes; No. 10 is the exception at about 0.516 in/ft. The most common sizes are No. 7, No. 9 and No. 11, used on milling spindles and arbors. B&S shanks often have a tang or are drawn in with a drawbar on milling machines.

Jarno taper dimensions

Jarno No. 2: large end 0.2500 in, small end 0.2000 in, length 1.00 in
Jarno No. 3: large end 0.3750 in, small end 0.3000 in, length 1.50 in
Jarno No. 4: large end 0.5000 in, small end 0.4000 in, length 2.00 in
Jarno No. 5: large end 0.6250 in, small end 0.5000 in, length 2.50 in
Jarno No. 6: large end 0.7500 in, small end 0.6000 in, length 3.00 in
Jarno No. 7: large end 0.8750 in, small end 0.7000 in, length 3.50 in
Jarno No. 8: large end 1.0000 in, small end 0.8000 in, length 4.00 in
Jarno No. 9: large end 1.1250 in, small end 0.9000 in, length 4.50 in
Jarno No. 10: large end 1.2500 in, small end 1.0000 in, length 5.00 in
Jarno No. 11: large end 1.3750 in, small end 1.1000 in, length 5.50 in
Jarno No. 12: large end 1.5000 in, small end 1.2000 in, length 6.00 in
Jarno No. 13: large end 1.6250 in, small end 1.3000 in, length 6.50 in
Jarno No. 14: large end 1.7500 in, small end 1.4000 in, length 7.00 in
Jarno No. 15: large end 1.8750 in, small end 1.5000 in, length 7.50 in
Jarno No. 16: large end 2.0000 in, small end 1.6000 in, length 8.00 in
Jarno No. 17: large end 2.1250 in, small end 1.7000 in, length 8.50 in
Jarno No. 18: large end 2.2500 in, small end 1.8000 in, length 9.00 in
Jarno No. 19: large end 2.3750 in, small end 1.9000 in, length 9.50 in
Jarno No. 20: large end 2.5000 in, small end 2.0000 in, length 10.00 in

Jarno rule: large end = number ÷ 8 in, small end = number ÷ 10 in, length = number ÷ 2 in. The taper is always 0.600 in per foot (0.050 in per inch on diameter, 1:20), and the angle from center is 1.4321°.

How to tell B&S, Jarno and Morse apart

All three look alike by eye. Compute taper per foot: B&S about 0.500, Jarno 0.600, Morse 0.599 to 0.631 depending on size. Jarno and Morse are close enough that you must also check diameters: a Jarno No. 8 large end is exactly 1.0000 in, while no Morse size has a 1.0000 in gauge diameter.

Worked example: identify a dividing head center

A center shank measures 0.7195 in large end, 0.6002 in small end, 2.875 in long. Taper per foot = (0.7195 − 0.6002) ÷ 2.875 × 12 = 0.498 in/ft, so it is B&S. The row with 0.7201 / 0.6000 / 2.88 is B&S No. 7.

Worked example: set a taper attachment for Jarno

A Jarno No. 6 is 0.750 in large and 0.600 in small over 3.000 in. Taper per foot = 0.600 in/ft. Set the taper attachment to 0.600 in/ft, or to an angle of atan(0.025) = 1.4321° per side. Over a 3.000 in length, the diameter changes 0.150 in, so a 0.075 in change in radius.

Common problems

Using a Morse reamer on a B&S socket, which bells the mouth. Trusting markings on old tooling; resurfaced shanks can be undersize. Forgetting that B&S milling shanks often need a drawbar; a B&S taper alone does not resist side load.

FAQ

What taper per foot is Brown & Sharpe?

About 0.500 in per foot.

What taper per foot is Jarno?

Exactly 0.600 in per foot.

What is the most common B&S taper?

No. 7, No. 9 and No. 11.

How do I size a Jarno taper?

Large end = number ÷ 8 in, small end = number ÷ 10, length = number ÷ 2.

Are Jarno and Morse interchangeable?

No. The rates are close but diameters differ.

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