Mechanical engineering fastener reference

Bolt Torque Chart

Estimate tightening torque and bolt preload for common SAE and metric steel fasteners. Select the thread, grade or property class, preload target, and friction assumption to see transparent dual-unit results.

Method: T = KFd
Systems: SAE inch and ISO metric
Outputs: N·m, lbf·ft, preload
Basis: Calculated starting estimates

JavaScript enables the live torque calculator, table filters, row comparison, copying, and chart. The complete default reference table and engineering guidance remain available below.

Interactive lookup

Bolt Torque and Preload Calculator

Calculates a general tightening-torque estimate from bolt proof strength, tensile stress area, target preload, nominal diameter, and nut factor.

Default reference: 1/2-13 UNC, SAE Grade 5, 75% of proof load, and K = 0.20 gives approximately 75.4 lbf·ft (102 N·m) and 9.05 kip (40.2 kN) preload.

Important application limit

Use this result as a calculated starting estimate, not as a manufacturer torque specification. Coating, lubricant, prevailing torque, reuse, washers, bearing surfaces, tool method, and joint stiffness can materially change the preload produced by a given torque.

Calculated reference

SAE and Metric Bolt Torque Chart

Default values use 75% of minimum proof load with K = 0.20 for dry/plain and K = 0.15 for the lubricated reference condition.

Search by designation or filter by standard system. Select up to four rows to compare the calculated torque values in the chart below.

Calculated general-purpose bolt torque estimates. Every torque cell shows N·m first and lbf·ft second. Values are not application-specific tightening specifications.
Compare				Pitch / TPI		Grade 2 / Class 8.8		Grade 5 / Class 10.9		Grade 8 / Class 12.9		Row action
Compare				Pitch / TPI		Dry K=.20	Lubed K=.15	Dry K=.20	Lubed K=.15	Dry K=.20	Lubed K=.15	Row action
	1/4-20 UNC	SAE inch	UNC	20 TPI	0.0318 in²	7.42 N·m 5.47 lbf·ft	5.56 N·m 4.10 lbf·ft	11.5 N·m 8.45 lbf·ft	8.59 N·m 6.34 lbf·ft	16.2 N·m 11.9 lbf·ft	12.1 N·m 8.95 lbf·ft
	1/4-28 UNF	SAE inch	UNF	28 TPI	0.0364 in²	8.48 N·m 6.25 lbf·ft	6.36 N·m 4.69 lbf·ft	13.1 N·m 9.66 lbf·ft	9.82 N·m 7.25 lbf·ft	18.5 N·m 13.6 lbf·ft	13.9 N·m 10.2 lbf·ft
	5/16-18 UNC	SAE inch	UNC	18 TPI	0.0524 in²	15.3 N·m 11.3 lbf·ft	11.5 N·m 8.45 lbf·ft	23.6 N·m 17.4 lbf·ft	17.7 N·m 13.1 lbf·ft	33.3 N·m 24.6 lbf·ft	25.0 N·m 18.4 lbf·ft
	5/16-24 UNF	SAE inch	UNF	24 TPI	0.0581 in²	16.9 N·m 12.5 lbf·ft	12.7 N·m 9.36 lbf·ft	26.1 N·m 19.3 lbf·ft	19.6 N·m 14.5 lbf·ft	36.9 N·m 27.2 lbf·ft	27.7 N·m 20.4 lbf·ft
	3/8-16 UNC	SAE inch	UNC	16 TPI	0.0775 in²	27.1 N·m 20.0 lbf·ft	20.3 N·m 15.0 lbf·ft	41.9 N·m 30.9 lbf·ft	31.4 N·m 23.2 lbf·ft	59.1 N·m 43.6 lbf·ft	44.3 N·m 32.7 lbf·ft
	3/8-24 UNF	SAE inch	UNF	24 TPI	0.0878 in²	30.7 N·m 22.6 lbf·ft	23.0 N·m 17.0 lbf·ft	47.4 N·m 35.0 lbf·ft	35.6 N·m 26.2 lbf·ft	67.0 N·m 49.4 lbf·ft	50.2 N·m 37.1 lbf·ft
	7/16-14 UNC	SAE inch	UNC	14 TPI	0.1063 in²	43.4 N·m 32.0 lbf·ft	32.5 N·m 24.0 lbf·ft	67.0 N·m 49.4 lbf·ft	50.2 N·m 37.1 lbf·ft	94.6 N·m 69.8 lbf·ft	70.9 N·m 52.3 lbf·ft
	7/16-20 UNF	SAE inch	UNF	20 TPI	0.1187 in²	48.4 N·m 35.7 lbf·ft	36.3 N·m 26.8 lbf·ft	74.8 N·m 55.2 lbf·ft	56.1 N·m 41.4 lbf·ft	106 N·m 77.9 lbf·ft	79.2 N·m 58.4 lbf·ft
	1/2-13 UNC	SAE inch	UNC	13 TPI	0.1419 in²	66.1 N·m 48.8 lbf·ft	49.6 N·m 36.6 lbf·ft	102 N·m 75.4 lbf·ft	76.7 N·m 56.5 lbf·ft	144 N·m 106 lbf·ft	108 N·m 79.8 lbf·ft
	1/2-20 UNF	SAE inch	UNF	20 TPI	0.1600 in²	74.5 N·m 55.0 lbf·ft	55.9 N·m 41.2 lbf·ft	115 N·m 85.0 lbf·ft	86.4 N·m 63.7 lbf·ft	163 N·m 120 lbf·ft	122 N·m 90.0 lbf·ft
	9/16-12 UNC	SAE inch	UNC	12 TPI	0.1819 in²	95.4 N·m 70.4 lbf·ft	71.5 N·m 52.8 lbf·ft	147 N·m 109 lbf·ft	111 N·m 81.6 lbf·ft	208 N·m 154 lbf·ft	156 N·m 115 lbf·ft
	9/16-18 UNF	SAE inch	UNF	18 TPI	0.2030 in²	106 N·m 78.5 lbf·ft	79.8 N·m 58.9 lbf·ft	164 N·m 121 lbf·ft	123 N·m 91.0 lbf·ft	232 N·m 171 lbf·ft	174 N·m 128 lbf·ft
	5/8-11 UNC	SAE inch	UNC	11 TPI	0.2260 in²	132 N·m 97.1 lbf·ft	98.7 N·m 72.8 lbf·ft	203 N·m 150 lbf·ft	153 N·m 113 lbf·ft	287 N·m 212 lbf·ft	215 N·m 159 lbf·ft
	5/8-18 UNF	SAE inch	UNF	18 TPI	0.2560 in²	149 N·m 110 lbf·ft	112 N·m 82.5 lbf·ft	230 N·m 170 lbf·ft	173 N·m 127 lbf·ft	325 N·m 240 lbf·ft	244 N·m 180 lbf·ft
	3/4-10 UNC	SAE inch	UNC	10 TPI	0.3345 in²	234 N·m 172 lbf·ft	175 N·m 129 lbf·ft	361 N·m 267 lbf·ft	271 N·m 200 lbf·ft	510 N·m 376 lbf·ft	383 N·m 282 lbf·ft
	3/4-16 UNF	SAE inch	UNF	16 TPI	0.3730 in²	261 N·m 192 lbf·ft	196 N·m 144 lbf·ft	403 N·m 297 lbf·ft	302 N·m 223 lbf·ft	569 N·m 420 lbf·ft	427 N·m 315 lbf·ft
	7/8-9 UNC	SAE inch	UNC	9 TPI	0.4617 in²	226 N·m 167 lbf·ft	169 N·m 125 lbf·ft	582 N·m 429 lbf·ft	437 N·m 322 lbf·ft	822 N·m 606 lbf·ft	616 N·m 455 lbf·ft
	7/8-14 UNF	SAE inch	UNF	14 TPI	0.5095 in²	249 N·m 184 lbf·ft	187 N·m 138 lbf·ft	642 N·m 474 lbf·ft	482 N·m 355 lbf·ft	907 N·m 669 lbf·ft	680 N·m 502 lbf·ft
	1-8 UNC	SAE inch	UNC	8 TPI	0.6057 in²	339 N·m 250 lbf·ft	254 N·m 187 lbf·ft	873 N·m 644 lbf·ft	654 N·m 483 lbf·ft	1232 N·m 909 lbf·ft	924 N·m 681 lbf·ft
	1-12 UNF	SAE inch	UNF	12 TPI	0.6630 in²	371 N·m 274 lbf·ft	278 N·m 205 lbf·ft	955 N·m 704 lbf·ft	716 N·m 528 lbf·ft	1348 N·m 995 lbf·ft	1011 N·m 746 lbf·ft
	M5 × 0.8	ISO metric	Metric coarse	0.8 mm pitch	14.2 mm²	6.17 N·m 4.55 lbf·ft	4.63 N·m 3.41 lbf·ft	8.83 N·m 6.51 lbf·ft	6.62 N·m 4.88 lbf·ft	10.3 N·m 7.61 lbf·ft	7.74 N·m 5.71 lbf·ft
	M6 × 1.0	ISO metric	Metric coarse	1 mm pitch	20.1 mm²	10.5 N·m 7.75 lbf·ft	7.88 N·m 5.81 lbf·ft	15.0 N·m 11.1 lbf·ft	11.3 N·m 8.32 lbf·ft	17.6 N·m 13.0 lbf·ft	13.2 N·m 9.72 lbf·ft
	M8 × 1.25	ISO metric	Metric coarse	1.25 mm pitch	36.6 mm²	25.5 N·m 18.8 lbf·ft	19.1 N·m 14.1 lbf·ft	36.5 N·m 26.9 lbf·ft	27.3 N·m 20.2 lbf·ft	42.6 N·m 31.4 lbf·ft	32.0 N·m 23.6 lbf·ft
	M8 × 1.0	ISO metric	Metric fine	1 mm pitch	39.2 mm²	27.3 N·m 20.1 lbf·ft	20.4 N·m 15.1 lbf·ft	39.0 N·m 28.8 lbf·ft	29.3 N·m 21.6 lbf·ft	45.6 N·m 33.6 lbf·ft	34.2 N·m 25.2 lbf·ft
	M10 × 1.5	ISO metric	Metric coarse	1.5 mm pitch	58.0 mm²	50.5 N·m 37.2 lbf·ft	37.8 N·m 27.9 lbf·ft	72.2 N·m 53.2 lbf·ft	54.1 N·m 39.9 lbf·ft	84.4 N·m 62.2 lbf·ft	63.3 N·m 46.7 lbf·ft
	M10 × 1.25	ISO metric	Metric fine	1.25 mm pitch	61.2 mm²	53.2 N·m 39.3 lbf·ft	39.9 N·m 29.5 lbf·ft	76.2 N·m 56.2 lbf·ft	57.1 N·m 42.1 lbf·ft	89.0 N·m 65.7 lbf·ft	66.8 N·m 49.3 lbf·ft
	M12 × 1.75	ISO metric	Metric coarse	1.75 mm pitch	84.3 mm²	88.0 N·m 64.9 lbf·ft	66.0 N·m 48.7 lbf·ft	126 N·m 92.9 lbf·ft	94.4 N·m 69.6 lbf·ft	147 N·m 109 lbf·ft	110 N·m 81.4 lbf·ft
	M12 × 1.5	ISO metric	Metric fine	1.5 mm pitch	88.1 mm²	92.0 N·m 67.9 lbf·ft	69.0 N·m 50.9 lbf·ft	132 N·m 97.1 lbf·ft	98.7 N·m 72.8 lbf·ft	154 N·m 113 lbf·ft	115 N·m 85.1 lbf·ft
	M14 × 2.0	ISO metric	Metric coarse	2 mm pitch	115.4 mm²	141 N·m 104 lbf·ft	105 N·m 77.8 lbf·ft	201 N·m 148 lbf·ft	151 N·m 111 lbf·ft	235 N·m 173 lbf·ft	176 N·m 130 lbf·ft
	M14 × 1.5	ISO metric	Metric fine	1.5 mm pitch	124.5 mm²	152 N·m 112 lbf·ft	114 N·m 83.9 lbf·ft	217 N·m 160 lbf·ft	163 N·m 120 lbf·ft	254 N·m 187 lbf·ft	190 N·m 140 lbf·ft
	M16 × 2.0	ISO metric	Metric coarse	2 mm pitch	156.7 mm²	218 N·m 161 lbf·ft	164 N·m 121 lbf·ft	312 N·m 230 lbf·ft	234 N·m 173 lbf·ft	365 N·m 269 lbf·ft	274 N·m 202 lbf·ft
	M16 × 1.5	ISO metric	Metric fine	1.5 mm pitch	167.2 mm²	233 N·m 172 lbf·ft	175 N·m 129 lbf·ft	333 N·m 246 lbf·ft	250 N·m 184 lbf·ft	389 N·m 287 lbf·ft	292 N·m 215 lbf·ft
	M18 × 2.5	ISO metric	Metric coarse	2.5 mm pitch	192.5 mm²	312 N·m 230 lbf·ft	234 N·m 172 lbf·ft	431 N·m 318 lbf·ft	323 N·m 239 lbf·ft	504 N·m 372 lbf·ft	378 N·m 279 lbf·ft
	M18 × 1.5	ISO metric	Metric fine	1.5 mm pitch	216.2 mm²	350 N·m 258 lbf·ft	263 N·m 194 lbf·ft	485 N·m 357 lbf·ft	363 N·m 268 lbf·ft	566 N·m 418 lbf·ft	425 N·m 313 lbf·ft
	M20 × 2.5	ISO metric	Metric coarse	2.5 mm pitch	244.8 mm²	441 N·m 325 lbf·ft	330 N·m 244 lbf·ft	610 N·m 450 lbf·ft	457 N·m 337 lbf·ft	712 N·m 525 lbf·ft	534 N·m 394 lbf·ft
	M20 × 1.5	ISO metric	Metric fine	1.5 mm pitch	271.5 mm²	489 N·m 360 lbf·ft	367 N·m 270 lbf·ft	676 N·m 499 lbf·ft	507 N·m 374 lbf·ft	790 N·m 583 lbf·ft	593 N·m 437 lbf·ft
	M22 × 2.5	ISO metric	Metric coarse	2.5 mm pitch	303.4 mm²	601 N·m 443 lbf·ft	451 N·m 332 lbf·ft	831 N·m 613 lbf·ft	623 N·m 460 lbf·ft	971 N·m 716 lbf·ft	728 N·m 537 lbf·ft
	M22 × 1.5	ISO metric	Metric fine	1.5 mm pitch	333.1 mm²	659 N·m 486 lbf·ft	495 N·m 365 lbf·ft	912 N·m 673 lbf·ft	684 N·m 505 lbf·ft	1066 N·m 786 lbf·ft	800 N·m 590 lbf·ft
	M24 × 3.0	ISO metric	Metric coarse	3 mm pitch	352.5 mm²	761 N·m 562 lbf·ft	571 N·m 421 lbf·ft	1053 N·m 777 lbf·ft	790 N·m 583 lbf·ft	1231 N·m 908 lbf·ft	923 N·m 681 lbf·ft
	M24 × 2.0	ISO metric	Metric fine	2 mm pitch	384.4 mm²	830 N·m 612 lbf·ft	623 N·m 459 lbf·ft	1149 N·m 847 lbf·ft	861 N·m 635 lbf·ft	1342 N·m 990 lbf·ft	1007 N·m 743 lbf·ft

The lower, medium, and high strength groups pair SAE Grade 2/5/8 with metric property classes 8.8/10.9/12.9 for compact comparison. These are different standards, not direct grade equivalents. “Lubricated” is an illustrative K = 0.15 case, not a universal lubricant correction. Grade 2 and property class 8.8 use diameter-dependent proof-stress bands within the listed range.

Selected-row comparison

Compare Bolt Torque by Size and Strength

The chart uses N·m so SAE and metric rows can share one axis. Change the table’s condition or strength filter to control the plotted series.

The reference table above contains the comparison values. JavaScript enables row selection, the responsive chart, and the accessible chart-data view.

What a Bolt Torque Value Means

A torque value is an indirect attempt to create bolt preload. In the simplified relationship T = KFd, torque T depends on the assumed nut factor K, target preload F, and nominal diameter d. It is not a direct measure of clamp force.

Diameter
Sets the torque arm and thread geometry. Proof strength
Sets the reference elastic load limit. Preload target
Controls the desired clamp force. Nut factor
Represents thread and bearing friction.

Two published charts can give different values for the same bolt because they use different preload percentages, friction assumptions, coatings, strength values, or rounding rules.

When Not to Use a Generic Bolt Torque Chart

Use the governing manufacturer, equipment, structural, flange, or engineered tightening procedure when the assembly has its own specification. Do not substitute this chart for:

Special tightening methods

Torque-to-yield or torque-angle fasteners
Turn-of-nut or direct-tension-indicator procedures
Hydraulic tensioning or controlled elongation

Safety-critical assemblies

Wheel and axle fasteners
Lifting, aerospace, medical, or pressure-boundary joints
Critical rotating equipment

Condition-sensitive joints

Gasketed flanges
Prevailing-torque or self-locking hardware
Coated, plated, reused, damaged, or specialty-alloy fasteners

How the Bolt Torque Chart Is Calculated

The calculator first estimates tensile stress area from the thread geometry. It multiplies that area by the applicable proof stress to obtain proof load, applies the selected preload percentage, and then estimates tightening torque.

Resolve thread geometry: nominal diameter and TPI or pitch.
Estimate tensile stress area: the effective threaded area carrying axial load.
Calculate proof load: proof stress × tensile stress area.
Set target preload: preload percentage × proof load.
Estimate torque: nut factor × preload × nominal diameter.

Primary relationship T = K × F × d

T is tightening torque, K is the empirical nut factor, F is target preload, and d is nominal bolt diameter.

Tensile stress area equations used

Unified inch threads: A_t = (π/4) × (d − 0.9743/n)², where n is threads per inch.

ISO metric threads: A_s = (π/4) × (d − 0.9382p)², where pitch p and diameter d are in millimetres.

Internal calculation: The page converts all force and length quantities to SI before calculating N·m, then converts the displayed result to lbf·ft and lbf·in.

Worked Bolt Torque Examples

1/2-13 UNC SAE Grade 5

Assumptions: tensile stress area 0.1419 in², proof stress 85 ksi, 75% preload, and K = 0.20.

Proof load: approximately 12.1 kip.

Target preload: approximately 9.05 kip.

Torque: approximately 102 N·m or 75.4 lbf·ft.

Sanity check: changing only K from 0.20 to 0.15 reduces the calculated torque by 25% while target preload remains unchanged.

M10 × 1.5 Class 8.8

Assumptions: tensile stress area approximately 58.0 mm², proof stress 580 MPa, 75% preload, and K = 0.20.

Proof load: approximately 33.6 kN.

Target preload: approximately 25.2 kN.

Torque: approximately 50.5 N·m or 37.2 lbf·ft.

Sanity check: a project-specific lubricant or coating can require a substantially different tested nut factor.

Dry vs. Lubricated Bolt Torque

“Dry” and “lubricated” are not universal engineering properties. The same nominal lubricant description can produce different friction at the threads and under the rotating bearing surface. Plating, wax, oil, anti-seize, washers, surface roughness, installation speed, temperature, and reuse all influence the torque-preload relationship.

Why published charts disagree

A chart using K = 0.15 will show 25% less torque than a chart using K = 0.20 for the same bolt and target preload. A chart using 70% of proof load will also be about 6.7% lower than one using 75%, before any other differences are considered.

Practical tightening workflow

Confirm the fastener designation, grade marking, material, coating, and condition.
Check the equipment or joint documentation for a controlling specification.
Use a tested torque-tension relationship when preload accuracy matters.
Use a calibrated tool in an appropriate operating range.
Follow the required tightening sequence, staging, and recheck procedure.
Record the actual lubricant, torque method, and assumptions used.

Engineering Basis, Scope, and Data Rights

Scope: common carbon- and alloy-steel unified inch and ISO metric fasteners included in this limited calculated reference.

The torque cells are original calculations from the displayed equations and assumptions. They are not copied manufacturer torque specifications and do not reproduce a complete commercial standards table.

NASA RP-1228 — Fastener Design ManualSupports torque-preload methodology, friction limitations, lubrication effects, and general fastener-design context.
SAE J429_201405Controlling commercial reference for the scope and mechanical properties of SAE inch-series steel fastener grades.
ISO 898-1:2013 with Corrigendum 1Published commercial reference for metric property classes. ISO lists this edition as current and marked to be revised, with a successor project under development.
ASME B1.1-2024 and ISO 262:2023Support the unified inch and selected metric thread designation scope used by the page.

Dataset and Source-Check Details

Method: Calculated from T = KFd after proof-load and preload calculations
Default conditions: 75% of proof load; K = 0.20 dry/plain and K = 0.15 lubricated reference
Displayed units: N·m and lbf·ft; calculator also reports lbf·in and preload
Valid page range: 1/4 through 1 inch SAE rows; M5 through M24 metric rows listed in the table
Known exclusions: Specialty alloys, prevailing-torque hardware, structural installation methods, flanges, and manufacturer-specific assemblies
Rights status: Limited transformed calculations; CSV disabled because the cited standards are rights-sensitive
Dataset version: bolt-torque-v1.2
Source check: Official source pages verified August 9, 2026

Bolt Torque Chart FAQs

What torque should I use for a 1/2-13 Grade 5 bolt?

At 75% of proof load and K = 0.20, this page calculates approximately 102 N·m or 75.4 lbf·ft. Use the governing manufacturer or assembly specification when one exists because actual friction and joint conditions may require a different value.

How much should bolt torque be reduced when threads are lubricated?

Is bolt torque the same as bolt preload?

Can this chart be used for metric 8.8, 10.9, and 12.9 bolts?

Can I use this chart for structural bolts, flange bolts, or wheel lug nuts?

Use the Chart as a Transparent Starting Point

Select the exact bolt thread and grade, state the preload target and nut-factor assumption, and preserve those assumptions with the result. When joint reliability or safety depends on preload accuracy, replace the generic nut factor with tested torque-tension data or use the controlling engineered tightening method.