Interactive Screw Identifier
Pick head, drive, and thread system—get likely fastener matches and jump to tools.
Open toolUniversal Screw & Bolt Converter
Convert metric and imperial fasteners, thread pitch, and tap drill sizes instantly.
Fast, accurate, and designed for real workshop use.
More tools
Metric to Imperial Screw Converter
Full converter with direction control and all common sizes.
Open toolThread Pitch to TPI Converter
Convert mm pitch to TPI and back instantly while you type.
Open toolTap Drill Calculator
Tap drill diameter from thread size and pitch.
Open toolThread Identifier Tool
Match measured diameter and pitch to a thread standard.
Open toolBolt Torque Calculator
Recommended tightening torque by size and grade.
Open toolFastener Weight Calculator
Estimate weight by size, length, quantity, and material.
Open toolDrill Bit Size Converter
Number, letter, fractional inch, and millimeter drills.
Open toolGuides & references
Practical fastener and thread guides for mechanics, engineers, machinists, and DIY builders.
Metric vs imperial fasteners
When to use each system and how to convert between common sizes.
Bolt head markings
Read strength grades from stamps and symbols on bolt heads.
Thread pitch explained
Metric pitch in mm vs imperial TPI and coarse vs fine threads.
Why stainless bolts gall
What galling is and how to avoid seized stainless pairs.
Bolt vs screw difference
Nuts vs tapped holes, load paths, and everyday terminology.
Thread types explained
UNC, UNF, metric coarse/fine, and how to tell them apart.
How to measure thread pitch
Calipers, thread gauges, and repeatable shop techniques.
What is TPI?
Threads per inch and how they relate to metric pitch.
Tap drill basics
Choosing drill diameter for strong tapped holes.
Fastener materials guide
Steel, stainless, aluminum, and common coatings compared.
Metric thread tolerances
Classes like 6H and 6g and what they mean for fit.
Bolt strength grades
Metric 8.8–12.9 and SAE Grades 2, 5, and 8 in plain language.
Fastener reference system
Structured diagrams and tables—pair with tools when you need thread and size data.
Reference hub
Anatomy, thread types, drives, heads, and self-tapping vs self-drilling.
Screw anatomy
Head, shank, thread, and point—labeled diagram and what to measure.
Thread types
Metric, UNC, UNF, pipe—comparison and identification flow.
Screw head types
Hex, pan, truss, countersunk, oval, round, and more.
Screw drive types
Phillips, Torx, hex socket, slotted, Robertson, and torque notes.
Head shape profiles
Side-view diagrams: how heads sit on or below the surface.