ER collet chart: size, range and nut torque
ER32 holds about 2 to 22 mm and ER20 about 1 to 13 mm, and each collet only grips from its nominal size down to about 1 mm smaller. Tightening torque depends on the nut maker: for an ER32 standard nut REGO-FIX gives 136 N·m, Techniks 112 ft-lb (about 152 N·m) and Tungaloy 215.7 N·m, so use the value of the nut you own.
ER collet sizes ER8 to ER50
Clamping range as printed by two makers, the collapse of one collet, and the nut thread. The REGO-FIX range includes its micro-bore (MB) collets.
| Size | REGO-FIX range | PTP range | Each collet clamps | Nut thread | Mini nut thread | Slotted nut OD |
|---|---|---|---|---|---|---|
| ER8 | 1.0–5.0 (MB 0.2–0.9) mm [1] | 0.5–5 mm 9 collets [6] | 0.5 mm [6] | Mini nut only: M10 × 0.75 [7] | M10 × 0.75 [7] | - |
| ER11 | 1.0–7.0 (MB 0.2–0.9) mm [1] | 0.5–7 mm 13 collets [6] | 0.5 mm [6] | M14 × 0.75 [7][3] | M13 × 0.75 [7] | 19 mm (hex) [7] |
| ER16 | 1.0–10.0 (MB 0.2–0.9) mm [1] | 0.5–10 mm 10 collets [6] | 1 mm [5][6] | M22 × 1.5 [7][3] | M19 × 1 [7] | 32 mm [7][3] |
| ER20 | 1.0–13.0 mm [1] | 1–13 mm 12 collets [6] | 1 mm [5][6] | M25 × 1.5 [7][3] | M24 × 1 [7] | 35 mm [7][3] |
| ER25 | 1.0–17.0 mm [1] | 1–16 mm 15 collets [6] | 1 mm [5][6] | M32 × 1.5 [7][3] | M30 × 1 [7] | 42 mm [7][3] |
| ER32 | 2.0–22.0 mm [1] | 2–20 mm 18 collets [6] | 1 mm [5][6] | M40 × 1.5 [7][3] | - | 50 mm [7][3] |
| ER40 | 3.0–26.0 mm [1] | 3–26 mm 23 collets [6] | 1 mm [5][6] | M50 × 1.5 [7][3] | - | 63 mm [7][3] |
| ER50 | 6.0–36.0 mm [1] | 10–34 mm 12 collets [6] | 2 mm (PTP ER50 sizes) [6] | M64 × 2 [7][3] | - | 78 mm [7][3] |
Each collet clamps from its nominal size down to 1 mm less (0.5 mm for Ø 1, 1.5 and 2 mm) [5]. Collet OD and length are left out: we did not find two makers' tables that agree. PTP collets and nuts listed above are linked in the picker.
ER nut torque by maker
These tables disagree, often by a factor of two. They are for different nuts and different assumptions, so we show each maker's value as published and never average them. ft-lb ↔ N·m conversions (1 ft-lb = 1.3558 N·m) are ours and marked ≈.
Tighten to the value published by the maker of your nut, with a torque wrench. Too little lets the tool pull out; too much can damage the collet, the nut thread or the holder. Tungaloy notes its values are for the largest shank a collet takes and should be reduced for smaller shanks.
| Size | Shank Ø band | REGO-FIX ER / ERC (N·m) | REGO-FIX ERB bearing (N·m) | REGO-FIX ERM mini (N·m) | Techniks chart | Techniks PowerCOAT | Tungaloy ER / ER-Top |
|---|---|---|---|---|---|---|---|
| ER8 | MB 0.2–0.9 mm | not offered | not offered | 6 ≈ 4 ft-lb | 7 ft-lb ≈ 9 N·m [2] | - | - |
| 1.0–5.0 mm | not offered | not offered | 6 ≈ 4 ft-lb | ||||
| ER11 | MB 0.2–0.9 mm | 8 ≈ 6 ft-lb | not offered | 8 ≈ 6 ft-lb | 20 ft-lb ≈ 27 N·m [2] | 17 ft-lb ≈ 23 N·m [3] | 49 N·m ≈ 36 ft-lb; mini nut 29.4 N·m [4] |
| 1.0–2.9 mm | 8 ≈ 6 ft-lb | not offered | 8 ≈ 6 ft-lb | ||||
| 3.0–7.0 mm | 24 ≈ 18 ft-lb | not offered | 16 ≈ 12 ft-lb | ||||
| ER16 | MB 0.2–0.9 mm | 8 ≈ 6 ft-lb | not offered | 8 ≈ 6 ft-lb | 45 ft-lb ≈ 61 N·m [2] | 42 ft-lb ≈ 57 N·m [3] | 68.7 N·m ≈ 51 ft-lb; mini nut 39.2 N·m [4] |
| 1.0 mm | 8 ≈ 6 ft-lb | 6.4 ≈ 5 ft-lb | 8 ≈ 6 ft-lb | ||||
| 1.5–3.5 mm | 20 ≈ 15 ft-lb | 16 ≈ 12 ft-lb | 20 ≈ 15 ft-lb | ||||
| 4.0–4.5 mm | 40 ≈ 30 ft-lb | 32 ≈ 24 ft-lb | 24 ≈ 18 ft-lb | ||||
| 5.0–10.0 mm | 56 ≈ 41 ft-lb | 56 ≈ 41 ft-lb | 24 ≈ 18 ft-lb | ||||
| ER20 | 1.0 mm | 16 ≈ 12 ft-lb | 12 ≈ 9 ft-lb | 16 ≈ 12 ft-lb | 67 ft-lb ≈ 91 N·m [2] | 59 ft-lb ≈ 80 N·m [3] | 117.7 N·m ≈ 87 ft-lb; mini nut 78.5 N·m [4] |
| 1.5–6.5 mm | 32 ≈ 24 ft-lb | 24 ≈ 18 ft-lb | 28 ≈ 21 ft-lb | ||||
| 7.0–13.0 mm | 80 ≈ 59 ft-lb | 80 ≈ 59 ft-lb | 28 ≈ 21 ft-lb | ||||
| ER25 | 1.0–3.5 mm | 24 ≈ 18 ft-lb | 20 ≈ 15 ft-lb | 24 ≈ 18 ft-lb | 85 ft-lb ≈ 115 N·m [2] | 77 ft-lb ≈ 104 N·m [3] | 196.1 N·m ≈ 145 ft-lb [4] |
| 4.0–4.5 mm | 56 ≈ 41 ft-lb | 48 ≈ 35 ft-lb | 32 ≈ 24 ft-lb | ||||
| 5.0–7.5 mm | 80 ≈ 59 ft-lb | 72 ≈ 53 ft-lb | 32 ≈ 24 ft-lb | ||||
| 8.0–17.0 mm | 104 ≈ 77 ft-lb | 104 ≈ 77 ft-lb | 32 ≈ 24 ft-lb | ||||
| ER32 | 2.0–2.5 mm | 24 ≈ 18 ft-lb | 20 ≈ 15 ft-lb | not offered | 112 ft-lb ≈ 152 N·m [2] | 100 ft-lb ≈ 136 N·m [3] | 215.7 N·m ≈ 159 ft-lb [4] |
| 3.0–7.5 mm | 136 ≈ 100 ft-lb | 128 ≈ 94 ft-lb | not offered | ||||
| 8.0–22.0 mm | 136 ≈ 100 ft-lb | 136 ≈ 100 ft-lb | not offered | ||||
| ER40 | 3.0–26.0 mm | 176 ≈ 130 ft-lb | 176 ≈ 130 ft-lb | not offered | 126 ft-lb ≈ 171 N·m [2] | 130 ft-lb ≈ 176 N·m [3] | 245.1 N·m ≈ 181 ft-lb [4] |
| ER50 | 6.0–36.0 mm | 240 ≈ 177 ft-lb | 240 ≈ 177 ft-lb | not offered | - | 130 ft-lb ≈ 176 N·m [3] | 343.2 N·m ≈ 253 ft-lb [4] |
REGO-FIX [1]: values per shank band; nut codes as REGO-FIX prints them (ER / ERC standard and coolant, ERB / ERBC ball-bearing, ERM / ERMC mini). Techniks chart [2] gives one value per size for slotted and hex nuts (ER16 castle nut 20 ft-lb; ER25 mini nut 25 ft-lb). Techniks PowerCOAT [3]. Tungaloy [4].
How to read this chart
Range vs. collet. "ER32 holds 2 to 22 mm" means the family. One ER32 collet marked 12 grips about 11 to 12 mm. To hold a 1/2 in (12.7 mm) shank you need the collet whose range includes 12.7 mm, for example a 13 mm collet (12 to 13 mm).
Why the torque tables differ. REGO-FIX gives lower torque for small shanks and for mini nuts, and a separate column for its ball-bearing nut. Techniks prints one value per nut size. Tungaloy prints the torque for the largest shank and says to reduce it for smaller ones. None of these is wrong for its own nut; mixing them is.
PTP parts. PTP CNC Toolings publishes 112 single-size DIN 6499 ER collets and ER collet chucks in 6 ER sizes, on 9 tapers: ER16 on BT30, BT40, BT50, HSK-A100, HSK-A50, HSK-A63, SK30, SK40, SK50; ER20 on BT30, BT40, BT50, HSK-A100, HSK-A50, HSK-A63, SK30, SK40, SK50; ER25 on BT30, BT40, BT50, HSK-A100, HSK-A50, HSK-A63, SK30, SK40, SK50; ER32 on BT30, BT40, BT50, HSK-A100, HSK-A50, HSK-A63, SK30, SK40, SK50; ER40 on BT40, BT50, HSK-A100, HSK-A63, SK40, SK50; ER50 on BT40, BT50, SK40, SK50. BT ER chucks, SK ER chucks, HSK ER chucks.
Not sure which taper your holder needs? Use the spindle taper identifier. Need the pull stud too? Pull stud finder by machine.
Sources and last checked
| # | Source | What we took from it | Checked |
|---|---|---|---|
| 1 | REGO-FIX: Recommended tightening torque for ER clamping nuts (PDF)REGO-FIX's link returned HTTP 503 on 2 Nov 2026. We read the same REGO-FIX sheet from a copy posted on the Carbide 3D forum: copy (PDF). | Collet range per ER size and torque in N·m by shank Ø band for ER / ERC, ERB / ERBC and ERM / ERMC nuts (ER* column: ER standard and ER-UP collets). | 2 Nov 2026 |
| 2 | Techniks: Torque specifications chart (PDF, posted by a distributor) | One torque value per ER nut size and wrench type, in ft-lb. | 2 Nov 2026 |
| 3 | Techniks catalogue p. 62: ER PowerCOAT nuts and coolant nuts (PDF copy) | Nut thread, outside Ø and torque spec (ft-lb) per PowerCOAT nut. | 2 Nov 2026 |
| 4 | Tungaloy Report No. 413-E, tooling system BT interface, p. 23 (PDF) | Recommended clamping torque (N·m) for standard ER and ER-Top nuts, and its note to reduce torque for smaller shanks. | 2 Nov 2026 |
| 5 | Hoffmann Group: ER collet ER 32 (product page, DIN ISO 15488-B) | Rule: each collet clamps from nominal down to 1 mm less (0.5 mm for Ø 1, 1.5 and 2 mm). | 2 Nov 2026 |
| 6 | PTP CNC Toolings: ER collets DIN 6499 (120 models) | Clamping range of every PTP ER collet, ER8 to ER50. | 2 Nov 2026 |
| 7 | PTP CNC Toolings: ER clamping nuts (slotted, hex, mini, sealed) | Nut thread, outside Ø and length per nut type. | 2 Nov 2026 |
Found a value that differs from your maker's current catalogue? Email the correction with the page link and we fix it.
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Questions
What is the clamping range of an ER32 collet set?
REGO-FIX lists ER32 collets from 2.0 to 22.0 mm; PTP CNC Toolings lists 2 to 20 mm. Each single collet grips from its nominal size down to about 1 mm smaller.
What is the largest shank an ER20 collet holds?
REGO-FIX lists ER20 up to 13.0 mm and PTP's largest ER20 collet is 12 to 13 mm. So 13 mm (about 1/2 in) is the ER20 maximum in both tables.
How tight should an ER32 collet nut be?
It depends on the nut maker. REGO-FIX gives 136 N·m for its ER / ERC nut on 3 to 22 mm shanks (24 N·m for 2 to 2.5 mm), Techniks 112 ft-lb (about 152 N·m) for its slotted nut, Techniks PowerCOAT 100 ft-lb, and Tungaloy 215.7 N·m at full capacity. Use your nut maker's value with a torque wrench.
Why do ER torque charts disagree?
They are for different nuts and assumptions: REGO-FIX gives values per shank band and per nut type (standard, ball-bearing, mini), Techniks gives one value per size, and Tungaloy gives the value for the largest shank and says to reduce it for smaller shanks.
What thread is an ER32 nut?
M40 × 1.5. ER11 is M14 × 0.75, ER16 M22 × 1.5, ER20 M25 × 1.5, ER25 M32 × 1.5, ER40 M50 × 1.5 and ER50 M64 × 2 (PTP CNC Toolings and Techniks catalogues agree). Mini nuts use other threads, for example ER20 mini M24 × 1.
Can I hold an inch shank in a metric ER collet?
Yes if the inch size falls inside that collet's range. 1/2 in is 12.7 mm, which falls in a 13 mm collet's range (12 to 13 mm). Type the size in the picker above to see which collets cover it.
What does ER mean, and is it DIN 6499 or ISO 15488?
ER collets are made to DIN 6499; the international standard is ISO 15488 (Hoffmann lists its ER collets as DIN ISO 15488-B, PTP as DIN 6499).
Do I need a different nut for a ball-bearing or mini nut?
Yes. Bearing and mini nuts are separate parts with their own torque values: REGO-FIX lists lower torque for its ERM mini nut than for its standard nut on the same collet, and a mini nut uses a different thread.
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