Thread Pitch Calculator

Work out the tap drill size for a metric or imperial thread at a chosen percentage of thread engagement.

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Input
Output

About thread pitch calculator

Thread Pitch Calculator works entirely in the browser tab. Open it, use it, close it. Nothing about the session outlives the page.

Everything runs client side, which is the only arrangement where a privacy claim is checkable. Open the network tab and watch it stay empty.

You will find it under Engineering, alongside 8 other tools for the same sort of job.

Runs in this tab, so nothing you type is uploaded.

How to use it

01
Start it
Every control is on the tool itself. Keyboard shortcuts, where there are any, are listed beside it.
02
Watch it run
It updates in the page as you go. Nothing is sent anywhere, so it keeps working with the network off.
03
Close when done
Nothing is stored between visits. Reloading gives you a clean start rather than picking up where you left off.

Examples

M10 x 1.5 at 75% engagement
A common metric machine screw thread
Input
system: metric
majorDiameterMm: 10
pitchMm: 1.5
Output
Tap drill diameter mm: 8.5386
Tap drill diameter inches: 0.3362
Pitch mm: 1.5
Threads per inch: 16.9333
Major diameter mm: 10
Major diameter inches: 0.3937
Engagement percent: 75

Questions

Does Thread Pitch Calculator work offline?+

Yes. It is JavaScript running in this tab, so once the page has loaded it needs nothing further from the network. Put the machine in flight mode and it carries on. Nothing you do here is sent anywhere, because there is nowhere for it to go.

Does it remember anything between visits?+

No. Reload the page and it starts from nothing. There is no account, no saved state and no cookie holding your last session. That is a deliberate trade: it cannot lose your data because it never keeps any.

Is it accurate?+

Timing comes from performance.now(), the high resolution clock the browser provides, rather than from setInterval, which drifts by a few milliseconds every tick and compounds over minutes. What can still shift things is the browser throttling a tab in the background, so leave it visible if the timing matters.

Does it make a sound?+

Where a sound makes sense, it is generated with the Web Audio API rather than loaded as a file, so there is nothing to download and nothing to block. Browsers refuse to start audio until you have interacted with the page, which is why the first press is what switches it on.

Can I use Thread Pitch Calculator on a phone?+

Yes. The controls are sized for touch and the layout collapses to one column on a narrow screen. Bear in mind that a phone locking its screen will suspend the page, and timing stops with it.