ISO Metric Thread Calculator


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IThe UtileApp Metric Thread Calculator is the ideal tool for professionals and students working in mechanical design, machining, CAD, or maintenance.
It instantly provides all the fundamental dimensions of ISO metric threads (60° profile) with speed and precision — based on just two inputs: the nominal diameter and thread pitch.

Whether you’re a technician, machinist, designer, or mechanical engineering student, this app saves valuable time and reduces the risk of errors during tapping, turning, or dimensional inspection.

What It Calculates

For every Mxx × P combination, the calculator determines the main theoretical diameters according to ISO 68-1, including:

  • Nominal diameter (d) – reference thread size
  • Pitch (P) – distance between consecutive crests

External thread (bolt):

  • d₂ – pitch diameter (midpoint of the thread profile)
  • d₃ – minor diameter (root of the thread)

Internal thread (nut):

  • D₂ – internal pitch diameter
  • D₁ – minor diameter (tapping hole)

Additional results:

  • Thread depth: h = 0.61343 × P
  • Recommended tapping hole: ≈ D₁ or simply (d − P)
  • Optional check: compare your actual drilled hole to verify if it’s correct, oversized, or undersized

How It Works

  1. Select a standard M thread (e.g. M6×1.0, M10×1.5, M12×1.75, etc.)
  2. Or choose “Custom” and enter your own d and P
  3. (Optional) Enter a real hole diameter for automatic verification
  4. Click “Calculate Thread”
  5. Instantly get all main diameters and the optimal tapping hole — ready to copy into your notes or report

Example Calculation

For an M10 × 1.5 thread:

  • d = 10 mm
  • P = 1.5 mm

Results:

  • d₂ = 9.026 mm
  • d₃ = 8.160 mm
  • D₂ = 9.512 mm
  • D₁ = 8.377 mm
  • Recommended hole ≈ 8.4 mm
  • Thread depth h = 0.920 mm

All values are calculated using official ISO geometric formulas, ensuring accuracy and clarity.

Why Use It

  • ISO-accurate results for 60° metric threads
  • Instant summary of all theoretical diameters
  • Automatic verification of actual hole size
  • Ideal for training, inspection, and CAD design
  • Multilingual (compatible with Polylang via ua__())
  • Works on any device — desktop, tablet, or smartphone

Technical Details

Calculations are based on the standard triangular ISO thread geometry (60°) according to ISO 68-1 and ISO 965, assuming the basic profile (without specific tolerance classes).
The provided values are theoretical, suitable for:

  • CAD and design work
  • Tool or tap design
  • Preliminary production and maintenance checks

They do not replace tabulated tolerance values (e.g. 6g, 6H, 4h, etc.), but serve as a reliable reference for analysis, comparison, and pre-dimensioning.

Summary

The UtileApp Metric Thread (ISO) Calculator is an indispensable tool for anyone working with bolts, nuts, or tapping tools.
With just a few clicks, you can obtain:

  • All main diameters (d₂, d₃, D₂, D₁)
  • The optimal tapping hole
  • Theoretical thread depth
  • Consistency check for real measurements

Perfect for engineers, machinists, designers, and students who need fast, accurate thread data — without flipping through manuals or tables.