Thread Pitch Gauge - Tap Drill

Turn your iPhone into a precision thread pitch gauge, virtual caliper, and complete fastener reference — all in one app built for machinists, mechanics, engineers, and DIYers.

MEASURE THREAD PITCH
Place any bolt, screw, or fastener directly on your screen and align it with the on-screen guide lines. Adjust pitch with fine-grained controls (down to 0.001 mm), pinch to zoom, rotate for angled threads, and lock the gauge when you find a match. The app instantly shows matching thread standards with confidence ratings.

VIRTUAL CALIPER
Drag the on-screen jaws to measure outer diameters with real-time readout in millimeters or inches. The app suggests the nearest standard thread diameters so you can quickly identify unknown fasteners.

IDENTIFY ANY THREAD STANDARD
A built-in database covers the most widely used thread families:
• ISO Metric (M series — coarse & fine)
• Unified National Coarse (UNC)
• Unified National Fine (UNF) & Extra Fine (UNEF)
• National Pipe Taper (NPT)
• British Standard Pipe Taper (BSPT)
• SAE Machine Screw

Search, filter, and browse detailed specifications including pitch, TPI, major diameter, tap drill sizes, and clearance hole dimensions for every entry.

TAP DRILL & CLEARANCE HOLE CALCULATORS
Select any thread from the database and instantly get:
• Recommended tap drill in mm, decimal inch, and fractional inch
• Nearest standard metric and inch drill sizes
• Clearance hole diameters for close, normal, and loose fits

THREAD CONVERTER
Convert freely between pitch (mm), threads per inch (TPI), decimal inches, and millimeters. See the nearest standard threads for any value you enter.

DRILL SIZE REFERENCE
Complete reference tables for metric, number (#1–#80), letter (A–Z), and fractional (1/64" – 1") drill sizes with instant mm ↔ inch conversion.

GUIDED THREAD WIZARD
Not sure where to start? The step-by-step wizard walks you through:
1. Thread type (screw/bolt or pipe fitting)
2. Unit preference (metric or imperial)
3. Approximate diameter
4. Estimated pitch
…and returns ranked candidates with confidence levels.

SCREEN CALIBRATION
Accurate on-screen measurement requires calibration. Choose from three methods:
• Auto Device Preset — instant setup using known screen specs
• Credit Card — align a standard card for quick calibration
• Manual Ruler — the most precise method for demanding work

BUI