Screw Thread Data Calculator

Roger Pope

About this app

This screw thread calculator app provides all data required to machine and measure screw threads to standard tolerance bands selectable from a drop-down menu.

A 'ThreadFinder' option is included which lists parallel threads of all available types which have similar diameter to measured diameter of sample thread. These are listed in order of Pitch/TPI.

Select from various threads including ISO metric 'M', the modified metric 'MJ', Unified 'UN', modified Unified 'UNJ' and British Standard Whitworth form 'BSW', 'BSF', 'BSPP' & 'BSPT' variations (G, R, Rc & Rp) plus NPT, NPTR & PTF Dryseal variations; NPTF, PTF-SAE Short, PTF-SPL Short (Special Short), PTF-SPL Extra Short & F-PTF (Fine). CONDUIT threads; Pg, Metric Fine and BS Conduit are also included.

ACME thread options are currently under development.

Standard sizes are selected at a touch from scrolling list. Non-Standard threads can be input from keyboard in any Diameter & Pitch or Diameter &TPI combination depending on thread type selected.

LIMITS OF EFFECTIVE DIAMETER (PITCH DIAMETER) are displayed in addition to MEASUREMENT OVER SELECTED WIRE/PIN size. Both are calculated for the selected standard tolerance band.

All standard tolerance bands are available from drop-down menu and allowance can be made for PLATING or coating thickness with the use of a 'Slider' scale adjustment.

Software calculates the range of acceptable wire/pin sizes and any available pin which is within that calculated allowable range can then be input and used. The readings calculated give measurements required for screw cutting and screw thread inspection using the 3 WIRE METHOD. Effective/Pitch Diameter tolerances are also output for use with direct measurement methods.

Readings over pins for Internal Threads are provided as 'GO' & 'NO GO' GAUGE sizes which enables the manufacture of temporary soft gauges if necessary.

Final calculations can be held on screen, saved as a .pdf file or output to WIFI printer if correctly set up with print service software on your device. (Contact us for recommended app. - Current favorite seems to be 'Mopria Print Service' which is available in Google Play Store)

Default results are in MILLIMETRES with INCH output as optional selection.

The app contains NO ADVERTS but does have links to all major THREADING INSERT SUPPLIERS in order to help with sourcing required tools.

Ratings and reviews

Just downloaded the updated version. I have been playing with it to get used to it and found it very easy to use. I found that it will be a very useful tool. Well done and pretty much put together well. Would like to see pipe threads data and also Min. and Max tolerances on O.D. and I.D. I highly recommend this useful tool . Also was able to connect to printer easily and print out data. Very ,very satisfied with it.

2023: This is my go-to app for any type of thread work whether done on a lathe or by tap & die. It hasn't failed me even once and it just can't be beat. 2024: Still using this go-to app. Never had a single issue. One thing I'd like to see added would be a nut and bolt torque chart to cover most common applications.

Very nice and easy to use app. I would like to be able to input coating thicknesses as a min./max. range and also to the 5th place decimal (inches only). A calculator for STI threads would also be helpful.

What’s new

Home navigation button added