Contact Bolt Calculator
A torque value that disagrees with your wrench, a K factor you think should differ, a clamp-load conversion that doesn't match the joint spec, a calculator you wish existed — this page routes your message to the person who can re-run the numbers and verify them against the standards, not a form that vanishes into a queue.
Most replies within two business days — correction reports that affect calculator output are prioritized.
Answered Already, Most Likely
Most bolt and fastener questions are covered somewhere on the site. These are the destinations that resolve the majority of emails — worth a look before you write. The fastest path to a verified torque value is usually one of these pages.
Every email read by a humanPhoto: Unsplash- Bolt Torque Calculator — Torque ↔ Clamp Load
- The T = K·F·d Torque Formula, Explained
- K-Factor Table by Finish & Lubrication
- Reference Torque Chart by Grade & Size
- How the Torque ↔ Preload Conversion Works
- Torque Calculator FAQ on the Home Page
- Bolt Weight Calculator — Fastener Set Mass
- Bolt Shear Calculator — Single & Double Shear
What to Include for a Fast Reply
- ✓Browser & device (for UI glitches)
- ✓The nominal bolt diameter (and thread pitch, if entered)
- ✓The K value or the finish & lubrication selection
- ✓The clamp load or torque you input, with units
- ✓Bolt grade (ISO 898-1 class or SAE grade) if the strength check is involved
- ✓The result you expected vs. the result shown
- ✓A screenshot of your calculator inputs
A screenshot of your calculator inputs halves the back-and-forth.
Pick the Right Inbox
Four routes, four inboxes — each one lands with someone who can act on it. Unsure which fits? Use support@ and we will forward it ourselves.
Calculator Support
Calculation & Estimate Help
A torque value that disagrees with your torque wrench? A clamp load that looks too high for the bolt size? Send the inputs you entered — the nominal diameter, the K value or finish and lubrication selection, the force or torque, and the units — along with the result you expected versus the one shown.
Replies in ~2 business days
Corrections
Report a Formula or Data Error
The site computes the torque ↔ preload conversion from T = K·F·d with the lubrication factor, K constants by finish, torque scatter ranges, strength checks against ISO 898-1 and SAE J429 property classes, fastener set weights from ASME B18.2.1/B18.2.2 geometry, and AISC-style shear capacity. If any output or table value disagrees with those standards, send the page URL and the exact numbers.
Verified before anything changes
Product Feedback
Feature Requests & Ideas
Want a thread pitch calculator, a turn-of-nut or torsion method, a bolt length estimator, a flange bolt-pattern spacing tool, or a printable torque-spec sheet for the shop wall? We build from what mechanics, engineers, and fabricators actually need at the bench — including real stories from assembly floors.
Read every week
Partners
Partnerships & Education
Fastener manufacturers, distributor training teams, engineering schools, and apprenticeship programs — we are open to classroom integrations, co-developed calculators, printed torque-reference companions, and training materials for assembly crews.
Replies in ~4 business days
Who You’re Writing To
Three facts about the people behind the inbox, so you know what kind of answer to expect.
Bench-side experience
The answers are written by people who have stood at a workbench and argued about a torque spec — replies speak plain, not legal.
Standards checked by hand
Every numeric claim is re-derived against ISO 898-1, SAE J429, ASME B18 geometry, and AISC shear practice before it is sent, not after.
No sales layer
There is nothing to upsell and no quota to hit — the site carries no products, so no reply ever ends in a pitch.
What Happens After You Hit Send
No ticket numbers, no canned macros. Here is the actual path a message takes from your outbox to a verified answer — the same path whether you found a five-percent discrepancy in a torque value or want a new fastener type added.
| Step | What Happens | What It Means for You |
|---|---|---|
| 1 | A Person Reads It | No ticket bot, no autoresponder loop. Messages with exact inputs — the diameter, the K value, the lubrication choice, the force or torque — are reproducible, and reproducible messages get answered first. |
| 2 | We Re-Run the Numbers by Hand | For anything numeric, we rebuild your calculation by hand — the T = K·F·d conversion, the lubrication factor, the grade strength check, the fastener set weight, or the shear capacity — and compare against ISO 898-1, SAE J429, ASME B18 geometry, and published fastener references before replying. |
| 3 | You Get the Math Attached | The reply shows the formulas and the inputs that moved the number. If we were wrong, the reply says so plainly and the fix is dated on the page it affects. |
| 4 | Verified Fixes Go into the Data | Confirmed corrections feed the K-value, torque, geometry, and strength tables the calculators read from, and strong feature requests feed the roadmap. Your email stays with your thread, is never added to a list, and there are no lists to add it to. |
Quick Answers
The eight questions we hear most from mechanics, engineers, and fabricators.
How do I get a faster reply?▼
Include the exact inputs: the bolt diameter and grade you entered, the K value or the finish and lubrication selected, the clamp load or torque with its units, and the result you expected versus the one shown. Add a screenshot of your calculator inputs. That one message usually lets us reproduce and explain the difference in a single reply.
Do you offer live chat or phone support?▼
Not yet. Email lets us re-run the full calculation and verify every answer against ISO 898-1, SAE J429, ASME B18 geometry, and AISC shear practice before responding — which matters when the topic is a torque spec for a real joint or a capacity check for a loaded connection. We read every message and answer most within two business days.
Can you tell me exactly what torque my bolt needs?▼
We can tell you what the calculator's method says for the inputs you enter — and show every formula behind it, including the K factor and the lubrication term. But a real joint has real conditions: thread condition, coating, washer faces, tool accuracy, and the manufacturer's own installation specification are the ground truth. Treat the computed value as the strong hypothesis and confirm it against the joint's specification before you pull the wrench.
Why does my result differ from the bolt manufacturer's table?▼
Manufacturers publish torque tables with their own assumed friction conditions and often apply their own safety margins. Two tables for the same bolt can differ by twenty percent and both be correct for the conditions each assumed. Compare the K value, lubrication, and utilization behind each table before comparing final numbers — the discrepancy is almost always in the assumptions, not the arithmetic.
Do you sell bolts, tools, or torque wrenches?▼
No. The site sells nothing, carries no affiliate links to any manufacturer, supplier, or marketplace, and is not affiliated with any brand. Advertising is clearly labeled and separately handled — see the advertising section of the Privacy Policy for how that works.
Can I suggest a new calculator?▼
Please do — that is how the toolset grows. Send the problem you were trying to solve, the fastener and joint you were working with, and what you wished had been calculated for you. Requests that describe a real bench or design problem (e.g., 'can you account for a prevailing-torque locknut?') go to the top of the content queue.
Do you keep the calculations or screenshots I send you?▼
Only for as long as your thread is open. Whatever you include — inputs, screenshots, the result you expected — is used to reproduce the calculation and fix whatever you reported, then it is deleted. Your address is never added to a mailing list, because there is no mailing list, and nothing you send is shared with third parties.
Can I use the site's results in a customer quote or bid?▼
Yes — that is planning use, and it is what the tools are for. Run your own inputs, treat the output as your working figure, and verify it against the fastener manufacturer's published specification and your engineering review before committing. What you may not do is present the output as a manufacturer's certified torque table or a stamped engineering document — the Disclaimer covers the line in detail.
Still need a human? One tap away.
One inbox per purpose keeps your message from bouncing between desks.
Everything Links Back to the Tool
Every answer we send names the exact calculator input that changes — the diameter, the K value, the lubrication factor, the grade utilization — so the fix is something you can apply yourself in seconds.