CNC Calculators - Formula Factory

Section in active development

A growing collection of calculators for everything from feeds and speeds to G-code arc math. Built for machinists, programmers, and shop owners who need the right number fast — without the textbook lookup. Categories below show the planned scope; individual calculators ship as they’re built.

Conversion CalculatorsInch↔mm, decimal↔fraction, SFM↔m/min, RPM↔surface speed, feed rate, pressure, force, torque, temperature.Coolant & Lubrication CalculatorsFlow rate, pressure, mist flow, nozzle velocity, heat generation, chip evacuation, concentration.Cutting & Tooling CalculatorsEnd mills, drills, taps, thread mills, boring bars, turning, inserts, tool deflection, helix and ramp angles.Dimensions & Geometry CalculatorsBolt circles, hole patterns, true position, right triangles, chamfers, fillets, angles, degrees↔radians.Feeds & Speeds CalculatorsRPM, surface speed (SFM), feed rate, chip load, feed per tooth, plunge rate, MRR, time-to-machine — the core feed math.G-Code & CNC CalculatorsG-code converter, radius comp, feed-per-rev, line numbers, backlash, spiral/circular interp, canned cycles.Material & Weight CalculatorsPlate, bar, and tube weight, density, volume, center of gravity, cutting and workholding forces.Setup & Workholding CalculatorsVise jaw width, soft-jaw allowance, work and tool length offsets, clamping force, parallels, setup sheets.Tool Path & CAM CalculatorsStep-over, cutter engagement, spindle load, max chip thickness, trochoidal milling, helical interp, peck drilling.

About these calculators

CNC machining lives and dies by the numbers — spindle speed, feed rate, depth of cut, chip load, surface finish, and a dozen unit conversions. These calculators turn the formulas you already know into one-click answers so you can keep your eyes on the part instead of the textbook. Every result will include the equation used, the working units, and (where it makes sense) sensible defaults for common materials and tool types.

Quick-reference formulas

The most common math that shows up at the machine, in case you just need a quick number:

Quantity	Formula	Variables
Spindle RPM (imperial)	RPM = (SFM × 3.82) ÷ D	SFM = surface speed, D = tool diameter (in)
Cutting speed (metric)	Vc = (π × D × RPM) ÷ 1000	D in mm, result in m/min
Feed rate (IPM)	IPM = RPM × CL × Z	CL = chip load (in/tooth), Z = number of flutes
Material removal rate	MRR = IPM × DOC × WOC	DOC = axial depth, WOC = radial width of cut
SFM ↔ m/min	m/min = SFM × 0.3048	Surface feet per minute to meters per minute
Power (kW from MRR)	P = MRR × Kc	Kc = specific cutting force (N/mm²)

FAQ

Where should I start if I’m new to CNC programming?

Start with Feeds & Speeds — RPM and feed rate are the two most consequential numbers on any cutting operation. Once you’re comfortable there, move on to Cutting & Tooling for chip load and depth of cut, then Tool Path & CAM for step-over, engagement, and trochoidal math.

Imperial or metric — which units do these calculators use?

Most calculators will accept both and let you switch on the fly. The Conversion category covers the in-between cases — SFM to m/min, fractional drills to decimal, kg/mm³ to lb/in³, and the rest of the bilingual numbers a typical shop runs into.

Are these numbers safe to send straight to the machine?

Treat any calculated value as a starting point. Manufacturer-recommended SFM and chip loads vary by coating, coolant flow, and machine rigidity — always sanity-check against the tool maker’s data and dial in via cut tests before sending production parts.

Why isn’t a specific calculator available yet?

The CNC section is in active development. The category pages exist as placeholders for navigation and SEO; individual calculators are being built one at a time. Feeds & Speeds and Cutting & Tooling are next in line.

Can I request a calculator that’s not on the list?

Yes — if there’s a specific calculation you reach for often (or a niche one you can’t find anywhere else), the request queue is open. Higher-vote ideas tend to ship first.