What is the tightening torque for an M8 bolt?

For a coarse-thread M8 bolt, new and uncoated (µ total = 0.14): 24 Nm for class 8.8, 35 Nm for class 10.9 and 41 Nm for class 12.9. Stainless A2/A4 M8: about 21 Nm (class 70) or 29 Nm (class 80).

What is the torque spec for an M10 bolt?

Coarse-thread M10, dry/lightly oiled: 47 Nm (8.8), 69 Nm (10.9), 83 Nm rounds to 81 Nm in the VDI-based table (12.9). Stainless A2/A4 M10: about 44 Nm (70) or 58 Nm (80). Fine pitch M10×1.25 runs slightly higher: 49/72/84 Nm.

What do bolt classes 8.8, 10.9 and 12.9 mean?

The first number is tensile strength in hundreds of MPa; multiplying the two numbers gives yield strength in tens of MPa. So 8.8 = 800 MPa tensile / 640 MPa yield, 10.9 = 1000/900, 12.9 = 1200/1080. Higher class = higher preload = higher tightening torque for the same size.

Do lubricated bolts need less torque?

Yes. Torque overcomes friction, so lubrication changes everything: with MoS2 paste or assembly grease (µ ≈ 0.10) apply roughly 0.82× the table value; degreased dry threads (µ ≈ 0.20) need roughly 1.25×. Applying a dry-value torque to a well-lubricated bolt can over-stretch it past yield.

Are stainless steel bolt torques different from grade 8.8?

Yes — A2/A4 class 70 yields around 450 MPa versus 640 MPa for 8.8, so torques are lower, and stainless galls easily so friction is higher and anti-seize is recommended. Use the dedicated A2/A4 table, not the carbon-steel one.

Is there a torque difference between coarse and fine pitch?

Fine-pitch threads have a larger stress area, so they carry slightly higher preload and torque — for example M12×1.25 at 88 Nm (8.8) versus 81 Nm for coarse M12. Use the fine-pitch table for fine threads rather than approximating from coarse values.

What torque should I use for bolts threaded into aluminum?

Standard tables assume a steel nut or steel tapped hole. Threads tapped directly into aluminum such as 6061 or 7075 strip long before the bolt yields — reduce torque substantially (often to roughly 60% or per joint calculation), increase engagement length to at least 1.5–2×d, or use a threaded insert.

Can I download this torque chart as a PDF?

Yes — the complete chart (coarse, fine pitch and stainless A2/A4 tables with the lubrication corrections) is available as a free one-click PDF on this page, with no email required.

Metric Bolt Torque Chart — 8.8, 10.9, 12.9 & Stainless A2/A4 + Calculator

// Torque Calculator — size · class · lubrication

Size

Material

Class

Thread condition

47 Nm≈ 35 ft·lb

Coarse thread, new uncoated fastener, steel joint. For stainless, table values already assume µ ≈ 0.20; the MoS₂ option approximates anti-seize compound. Safety-critical joints: verify per VDI 2230 or the equipment manual.

Torque Chart — Coarse Thread, Classes 8.8 / 10.9 / 12.9

Values in newton-metres (Nm) for new, uncoated bolts with a steel nut or steel tapped hole, thread and head bearing surface lightly oiled (µ_total = 0.14), preload at 90% of yield per the VDI 2230 convention. If your bolts are lubricated or fully degreased, apply the correction factors below.

Maximum tightening torque, Nm — metric coarse thread
Size	Class 8.8	Class 10.9	Class 12.9
M3	1.3	2.0	2.3
M4	2.9	4.3	5.0
M5	5.8	8.4	9.9
M6	9.9	14.5	17
M8	24	35	41
M10	47	69	81
M12	81	119	139
M14	129	190	222
M16	198	291	341
M18	283	402	471
M20	402	570	667
M22	552	783	917
M24	691	981	1148
M27	1022	1452	1700
M30	1387	1969	2305
M33	1884	2676	3132
M36	2418	3435	4020

Reading the classes: the first figure is tensile strength in hundreds of MPa, and the product of both figures is yield in tens of MPa — so 8.8 = 800 MPa tensile / 640 MPa yield, 10.9 = 1000/900, 12.9 = 1200/1080. Same size, higher class, higher preload, higher torque. If your bolt head carries no class marking, treat it as 4.6/5.8 commercial hardware and do not use this table's values.

Stainless Steel A2 / A4 Torque Chart (Classes 70 & 80)

Stainless bolts are weaker than 8.8 (class 70 yields ≈450 MPa) and gall easily, so they get their own table — commonly published for µ_total ≈ 0.20 with anti-seize recommended. A2 (≈304 chemistry) and A4 (≈316, marine) share the same property classes, so torque values are identical; only corrosion resistance differs.

Maximum tightening torque, Nm — stainless A2/A4, coarse thread
Size	Class 70 (A2-70 / A4-70)	Class 80 (A2-80 / A4-80)
M3	1.1	1.5
M4	2.6	3.4
M5	5.1	6.8
M6	8.8	11.7
M8	21	29
M10	44	58
M12	74	99
M14	119	158
M16	183	244
M18	259	345
M20	364	485
M22	495	660
M24	630	840
M27	920	1225
M30	1246	1660

Ordering stainless hardware in non-catalog dimensions? We machine custom stainless bolts in A2/304 and A4/316 to drawing, from single pieces.

Fine Pitch Torque Chart

Fine threads have a larger tensile stress area than coarse threads of the same nominal size, so preload and torque run slightly higher. Don't approximate — use the dedicated values:

Maximum tightening torque, Nm — metric fine pitch (µ = 0.14)
Thread	Class 8.8	Class 10.9	Class 12.9
M8 × 1	26	38	44
M10 × 1.25	49	72	84
M12 × 1.25	88	129	151
M12 × 1.5	86	126	148
M14 × 1.5	138	203	237
M16 × 1.5	210	308	360
M18 × 1.5	308	438	513
M20 × 1.5	431	615	719
M22 × 1.5	580	826	966
M24 × 2	731	1044	1221

Dry vs Lubricated: the Correction Most Charts Skip

Tightening torque mostly fights friction — only a small share becomes bolt tension. Change the friction and the "right" torque changes with it, which is why quoting one number per size without stating the thread condition is meaningless:

Lightly oiled, as-delivered (µ ≈ 0.14): use the table values above — this is the standard assumption.
MoS₂ paste, assembly grease, wax (µ ≈ 0.10): multiply by ≈0.82. Applying dry-table torque to well-lubricated threads can stretch the bolt past yield.
Degreased, bone-dry threads (µ ≈ 0.20): multiply by ≈1.25 to reach the same preload.
Threads into aluminum (6061, 7075): the tapped hole strips before the bolt fails — cut torque substantially, use ≥1.5–2×d engagement, or fit a threaded insert. Details in our stainless-in-aluminum guide.

Quick Answers by Size

M5 bolt torque

Coarse M5: 5.8 Nm (8.8), 8.4 Nm (10.9), 9.9 Nm (12.9); stainless A2/A4-70 ≈ 5.1 Nm. Small screws are torn off easily by power tools — use a torque-limiting driver near these values.

M6 bolt torque

Coarse M6: 9.9 Nm (8.8), 14.5 Nm (10.9), 17 Nm (12.9); A2/A4-70 ≈ 8.8 Nm. M6 into tapped aluminum housings is the classic stripped-thread case — drop the torque or spec an insert.

M8 bolt torque

Coarse M8: 24 Nm (8.8), 35 Nm (10.9), 41 Nm (12.9); fine M8×1: 26/38/44 Nm; stainless 70/80: 21/29 Nm. The most-asked size on this chart — and the answer changes ±20% with lubrication, so check the thread condition first.

M10 bolt torque

Coarse M10: 47 Nm (8.8), 69 Nm (10.9), 81 Nm (12.9); fine M10×1.25: 49/72/84 Nm; stainless 70/80: 44/58 Nm.

M12 bolt torque

Coarse M12: 81 Nm (8.8), 119 Nm (10.9), 139 Nm (12.9). Automotive fine pitches are common here — M12×1.25 runs 88/129/151 Nm and M12×1.5 runs 86/126/148 Nm.

M14 bolt torque

Coarse M14: 129 Nm (8.8), 190 Nm (10.9), 222 Nm (12.9); M14×1.5: 138/203/237 Nm; stainless 70/80: 119/158 Nm.

M16 bolt torque

Coarse M16: 198 Nm (8.8), 291 Nm (10.9), 341 Nm (12.9); M16×1.5: 210/308/360 Nm. From M16 up, verify with a calibrated wrench — hand feel is hopeless at these levels.

M18 bolt torque

Coarse M18: 283 Nm (8.8), 402 Nm (10.9), 471 Nm (12.9); M18×1.5: 308/438/513 Nm.

M20 bolt torque

Coarse M20: 402 Nm (8.8), 570 Nm (10.9), 667 Nm (12.9); stainless 70/80: 364/485 Nm. Structural M20 connections normally follow the joint spec (e.g. EN 1090 preloading), not a generic chart.

M24 bolt torque

Coarse M24: 691 Nm (8.8), 981 Nm (10.9), 1148 Nm (12.9); M24×2: 731/1044/1221 Nm; stainless 70/80: 630/840 Nm. At this size, thread condition swings the number by hundreds of Nm — state it on the drawing. Large and oversize bolts beyond catalog ranges are our specialty: see large custom bolts.

Collection of custom machined shoulder bolts, socket head and special bolts in steel, stainless, titanium and black oxide finishes — Custom and non-standard bolts we machine — when the size you need isn't in any chart or catalog

When this chart doesn't apply: non-standard threads, oversize or repaired threads, special materials (titanium, brass), reused or coated bolts, and any safety-critical joint. Those need a per-joint calculation — and if the bolt itself can't be bought, we machine non-standard thread bolts and replacement bolts from a sample, from one piece, with the torque guidance included.

Torque Chart FAQ

24 Nm (8.8), 35 Nm (10.9), 41 Nm (12.9) — coarse thread, lightly oiled. Stainless A2/A4: 21 Nm (70) or 29 Nm (80).

Strength classes: first figure = tensile in hundreds of MPa, product of both = yield in tens of MPa. 8.8 → 800/640 MPa; 10.9 → 1000/900; 12.9 → 1200/1080.

Yes — with MoS₂ or assembly paste apply ≈0.82× the table value; degreased dry threads need ≈1.25×. Torque is mostly friction, so the thread condition decides the number.

No — A2/A4 class 70 is markedly weaker than 8.8 and galls without anti-seize. Use the dedicated stainless table above.

Slightly, yes: fine threads have a larger stress area — e.g. M12×1.25 takes 88 Nm (8.8) vs 81 Nm coarse. Use the fine-pitch table.

Tapped 6061/7075 strips before the bolt yields. Reduce torque substantially, use 1.5–2×d thread engagement, or spec a threaded insert.

Bolts tightened to these near-yield values may be reused only if the joint spec allows and they're undamaged; torque-to-yield and stretch bolts are single-use. When in doubt, replace — the bolt is the cheapest part of the joint.

Yes — download the free PDF with all three tables and the lubrication corrections. No email required.

Metric Bolt Torque Chart

Torque Chart — Coarse Thread, Classes 8.8 / 10.9 / 12.9

Stainless Steel A2 / A4 Torque Chart (Classes 70 & 80)

Fine Pitch Torque Chart

Dry vs Lubricated: the Correction Most Charts Skip

Quick Answers by Size

M5 bolt torque

M6 bolt torque

M8 bolt torque

M10 bolt torque

M12 bolt torque

M14 bolt torque

M16 bolt torque

M18 bolt torque

M20 bolt torque

M24 bolt torque

Torque Chart FAQ

Free PDF Chart

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