Machining calculators that do the math for you
Stop eyeballing feeds, speeds, and tap drill sizes. Sixty-five free tools for the shop math you do between cuts — built for the floor, not a textbook.
Speeds & Feeds
Machine Profiles
Set your machine once and get warned before a calculator exceeds its RPM or spindle power.
Feed & Speed Calculator
RPM and table feed together, from cutting speed, diameter, flutes, and chip load.
Cutting Speed Calculator
Convert surface feet per minute to spindle RPM for any material and tool diameter.
Feed Rate Calculator
Get table feed (IPM) from chip load, flute count, and spindle RPM.
Chip Load Calculator
Work backward from feed rate and RPM to find your actual chip load per tooth.
SFM ↔ RPM Calculator
Convert cutting speed to RPM, or RPM back to cutting speed, either direction.
Drill Speed Calculator
Spindle RPM for drilling any material at any drill diameter.
Lathe Turning Speed Calculator
RPM from cutting speed and workpiece diameter for turning operations.
Chip Thinning Calculator
Adjusted feed to compensate for thin chips at low radial engagement.
Horsepower Calculator
Estimate the spindle horsepower a cut actually requires before you run it.
Drilling
Drill Feed Calculator
Table feed (IPM) from spindle RPM and feed per revolution.
Peck Drilling Calculator
Number of pecks and final peck depth for a deep hole.
Spot Drill Depth Calculator
Depth to hit a target spot diameter at any included angle.
Drill Point Depth Calculator
Tip length by point angle, plus through-hole breakthrough allowance.
Drill Size Converter
Convert any drill size to its equivalent in every other system.
Fraction ↔ Letter ↔ Number Drill Chart
Every fraction matched against its closest letter and number drill.
Threading & Tapping
Tap Drill Size Calculator
The right pilot hole for any thread size and target thread engagement.
Thread Pitch Reference Chart
UNC, UNF, and metric thread pitches side by side.
Thread Depth Calculator
Single-point threading depth of cut for any pitch and thread form.
Thread Percentage Calculator
Find the actual thread engagement a drill size you already used produces.
Tap Feed Calculator
The exact feed rate rigid tapping requires, from RPM and thread pitch.
Metric ↔ Imperial Thread Converter
Pitch in mm to TPI, or TPI back to pitch, either direction.
Thread Pitch Calculator
Pitch, TPI, and lead together — handles multi-start threads correctly.
Thread Identification Guide
Match a measured diameter and pitch against common thread standards.
Turning
Turning Feed & Speed Calculator
RPM and feed rate together, from cutting speed, diameter, and feed per rev.
Constant Surface Speed Calculator
RPM at any diameter, checked against your machine's max RPM limit.
Turning Horsepower Calculator
Spindle power required for a turning cut, from speed, feed, and depth of cut.
Facing Speed Calculator
The RPM range a facing pass needs from outer diameter down to center.
Conversions & Reference
Decimal & Fraction Converter
Convert between decimal inches and the nearest standard fraction.
Metric & Imperial Converter
Length, and common machining units, converted both directions.
Drill Bit Size Chart
Number, letter, fractional, and metric drill sizes, cross-referenced.
Hardness Conversion Chart
Rockwell, Brinell, and Vickers hardness, cross-referenced.
Torque Conversion Calculator
Convert between ft-lb, in-lb, and Nm instantly.
Tap Drill & Thread Chart
Major diameter, pitch, and recommended tap drill for every common thread.
Cutting Speed Chart
SFM by material and tool type, for milling, drilling, and turning alike.
End Mill Size Chart
Standard, commonly stocked fractional and metric end mill diameters.
Allen Wrench (Hex Key) Size Chart
The hex key that fits a socket head cap screw of a given size.
Machining Math
Bolt Circle Calculator
X/Y coordinates for evenly spaced holes on any bolt circle.
Sine Bar & Angle Calculator
Gauge block stack height for any angle on a sine bar or sine plate.
Material Removal Rate Calculator
Estimate MRR from depth of cut, width of cut, and feed rate.
Surface Finish (Ra) Guide
What common Ra values actually look and feel like, and where they're used.
Surface Finish Calculator
Estimate theoretical Ra from feed and nose or corner radius.
Stepover Calculator
Scallop height and stepover for ball nose finishing passes.
Cutter Engagement Calculator
Radial engagement percentage and engagement angle from stepover.
Tool Deflection Calculator
Estimate end mill deflection from stickout, force, and shank material.
Trig Calculator
Sin, cos, tan and their inverses, without hunting for a calculator app.
Right Triangle Calculator
Solve every side and angle from any two known values.
Chord Length Calculator
Straight-line distance between two points on a circle.
Polar Coordinate Calculator
Convert polar (r, θ) to X/Y, or X/Y back to polar.
Angle Calculator
Angle and distance between two points, plus DMS ↔ decimal degrees.
Hole Pattern Calculator
X/Y coordinates for a full rectangular grid of holes.
Materials & Tolerances
ISO Fit & Tolerance Reference
Common ISO fit classes (H7/g6 and friends) and what they're for.
Steel & Aluminum Comparison Chart
Common grades side by side: machinability, strength, and typical uses.
Bolt Torque Spec Chart
Standard torque values by bolt size and grade, dry and lubricated.
Feed Calculator for 6061 Aluminum
RPM and feed rate with 6061's own recommended speed and chip load ranges.
Feed Calculator for 7075 Aluminum
RPM and feed rate tuned for 7075's higher strength and heat.
Feed Calculator for Delrin
RPM and feed rate tuned to avoid melting and gumming in acetal/POM.
Feed Calculator for Brass
RPM and feed rate for free-machining and lead-free brass grades.
Feed Calculator for Copper
RPM and feed rate tuned to fight built-up edge in soft, gummy copper.
Feed Calculator for Titanium
Low-speed, high-feed numbers for Ti-6Al-4V that manage heat and work hardening.
Feed Calculator for 1018 Steel
RPM and feed rate for the baseline general-purpose mild steel.
Feed Calculator for 4140 Steel
RPM and feed rate by heat-treat condition: annealed, normalized, or hardened.
Feed Calculator for Stainless 304
RPM and feed rate tuned to avoid work hardening in 304.
Feed Calculator for Stainless 316
RPM and feed rate for 316's gummier, more work-hardening-prone behavior.
Feed Calculator for Inconel
Conservative starting numbers for one of the toughest common materials to cut.
Why this shop math still matters
Modern CAM software will happily compute a toolpath at whatever speeds and feeds you tell it to use, but it won't tell you whether those numbers are actually right for the material, tool, and machine in front of you — that part is still on the machinist. Cutting speed depends on the material being cut and the tool material doing the cutting, not a number CAM assumes by default, and getting it wrong burns tools, burns time, or leaves a bad finish on a part that then has to be scrapped or reworked.
Reference numbers, not a substitute for judgment
Every calculator here gives a solid starting point based on standard reference data, not a guarantee for your specific machine, tool wear, or setup rigidity. Chatter, tool deflection, and coolant condition all shift what actually works in practice — dial in from these numbers, don't treat them as gospel, the same way you'd treat any handbook value on the shop floor.