Free tools

Free Machine Shop
Calculators & Reference Charts

Eight tools for the math and reference data every machinist needs. Shop rate, job quoting, profitability analysis, metal weight, speeds & feeds, tap drill sizes, hardness conversion, and surface finish. No signup. No email. Everything runs in your browser.

We build job tracking software for small machine shops. These are the tools we needed ourselves. No vendor bias, no paywall, no catch.

Calculators

Reference Tools

Reference

Metal Weight Calculator

Pick a shape, pick a material, enter dimensions. Get weight in pounds and kilograms plus an approximate material cost range. Imperial and metric units.

  • ·6 shapes: round bar, flat, plate, tube, hex, square
  • ·18 common shop materials with real densities
  • ·Imperial/metric unit toggle
  • ·Approximate $/lb cost range by alloy
  • ·PDF export with full calculation
Machining

Speeds & Feeds Calculator

Pick your material, tool coating, and operation. Get recommended SFM, RPM, chip load, feed rate, and MRR. Shows the formulas so you know why.

  • ·Milling (face, slot, profile) and drilling
  • ·HSS, carbide uncoated, TiAlN, AlTiN recommendations
  • ·Shows all formulas and intermediate values
  • ·Material removal rate output
  • ·PDF reference sheet
Reference

Tap Drill Size Chart

Complete tap drill chart for UNC, UNF, and Metric threads. See recommended drill sizes at 50%, 65%, and 75% thread engagement. Enter a custom drill to see the resulting thread percentage.

  • ·UNC, UNF, and Metric (ISO) thread standards
  • ·Tap drill sizes at 50/65/75% engagement
  • ·Custom drill size to thread % calculator
  • ·Search and filter to find any size instantly
  • ·PDF reference chart export
Reference

Hardness Conversion Chart

Mill cert says Brinell, drawing says Rockwell C. Type in one number, get every other hardness scale plus approximate tensile strength. Full ASTM E140 table for carbon and alloy steels.

  • ·HRC, HRB, Brinell, Vickers, Knoop, and tensile
  • ·Type any scale, get all others instantly
  • ·Interpolates between table values
  • ·Searchable full ASTM E140 table
  • ·PDF export of the whole chart
Reference

Surface Finish Conversion Chart

Drawing says Ra in micrometers, your profilometer reads microinches. Type in one, see every other unit. Plus which machining processes can actually hit your target finish.

  • ·Ra, Rz, and RMS in both µin and µm
  • ·ISO 1302 N-grade equivalents (N1 through N12)
  • ·Adjustable Ra-to-Rz ratio for your process
  • ·Process capability table: 20 operations
  • ·PDF export

Common questions about shop math

Start with your loaded labor cost, add machine depreciation spread across the hours you actually run, add allocated overhead, and divide by billable hours in a month. That's your break-even. Your real selling rate adds a target margin on top. The shop rate calculator does the math end to end.

These tools are free forever. No email gate, no ads, no tracking beyond the basic page view counter. Everything runs in your browser and your numbers stay on your computer. We built them because we needed them ourselves.

Feedback or a tool you wish existed? Email [email protected].