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Engineering calculator

A bench-side suite of 15 calculators for metric fasteners. Inputs validate as you type; every result is computed from the published standards — ISO 261, ISO 273, ISO 4014 / 4017 / 4762, ISO 4032, ISO 7089 / 7093, ISO 898-1, ISO 3506 and ASME B1.1.

Why we built this

Most fastener calculations are not difficult — they are just tedious, easy to get subtly wrong, and scattered across a dozen standards documents. Working out an M10 tightening torque means finding the proof load in ISO 898-1, choosing a friction coefficient that matches the surface, and remembering that the published tables usually assume a condition your parts are not in.

So we built the tools we use ourselves and put them on one page. Every result is computed from the published standards — ISO 261, ISO 273, ISO 4014 / 4017 / 4762, ISO 4032, ISO 7089 / 7093, ISO 898-1, ISO 3506 and ASME B1.1 — not from a lookup table someone typed out once. Nothing is stored, nothing needs an account, and every calculator shows the inputs it used so you can check the result rather than trust it.

  • Answers, not tables. Enter your case and read the number, instead of interpolating between rows.
  • Real surface conditions. Friction, material and property class are inputs, because they change the answer.
  • Standard sizes out. Results round to lengths and drills that exist, so what you specify can be supplied.
  • Straight to a quote. Each result links to the matching parts in our catalog when you are ready to order.

What each calculator does

Selecting and sizing the fastener

Start here when you know the joint but not the part. These work out the length, the engagement and the load the fastener can actually carry.

Bolt Length Calculator
Adds up clamp thickness, washers, nut height and projection, then rounds up to the next length that is actually stocked — so you order M8×45 instead of discovering M8×43 does not exist.
Thread Engagement Calculator
Minimum engagement length into steel, cast iron, aluminium, brass or plastic, so the threads in the parent material are not the weak point.
Thread Strip Strength Check
Checks the failure mode. A joint should fail by the bolt breaking, never by the internal thread stripping out of the parent part.
Bolt Shear Capacity Calculator
Single and double shear capacity by property class, for the cases where the bolt is loaded across the shank rather than along it.
Washer Size Selector
ISO 7089 normal against ISO 7093 large — the flat washer dimensions that decide whether the bearing surface is big enough for a soft material.
Helical Compression Spring Calculator
Rate, working force and Wahl-corrected shear stress for helical compression springs.

Tightening it correctly

Torque is a proxy for clamp force, and the relationship depends on friction. These make that relationship explicit instead of leaving it to a generic chart.

Tightening Torque Calculator
T = K · F · d with the friction coefficient picked from a real surface condition — dry, lightly oiled, zinc plated, waxed — rather than one assumed value for everything.
Preload from Torque Calculator
Works backwards: enter the torque your wrench actually delivers and read the clamp force it produces, as a force and as a percentage of proof load.

Machining the hole

The half of the joint that is not the fastener. Get these wrong and the part is scrap before the bolt is anywhere near it.

Tap Drill & Clearance Hole Calculator
Tap drill diameter for a target thread engagement, plus the three ISO 273 clearance grades — fine, medium and coarse.
Counterbore & Countersink Calculator
Counterbore and countersink dimensions to ISO 4762 and ISO 7721, so a socket head or a countersunk screw finishes flush.
Bolt Pattern (PCD) Calculator
Pitch circle geometry: chord length between holes and the X/Y coordinate of every hole, ready to type into a CNC program.

Looking something up

Reference tables you would otherwise be searching a PDF for, answered in one field.

Property Class & Material Lookup
Property class and material lookup — ISO 898-1 for steel, ISO 3506 for stainless, with proof and tensile figures.
Wrench / Socket Size Reference
Across-flats, Allen key and Torx sizes for every metric fastener, with the SAE equivalents.
Pitch ↔ TPI Converter
Metric pitch in millimetres converted to threads per inch, and back.
Metric ↔ Imperial Converter
Length, torque, force and pressure conversion, in the units these calculations actually use.

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