Mech Calc

Mech Calc is a machinist calculator that runs 100% offline. It asks for no network permission, so it works at the bench, on the shop floor, and anywhere your phone has no signal.

38 calculators, grouped by what you're doing:

CUTTING
• Speeds & Feeds. Spindle speed, feed rate, SFM, chip load, MRR and power from your material, tool and diameter, with a live cut setup diagram.
• Turning. RPM, cut time and part-off.
• Surface Finish. Ra from turning and milling passes.
• Grinding. Wheel surface speed, aggressiveness factor and grit size.
• Sheet Metal. Bend allowance, bend deduction and flat pattern from K-factor tables by temper and R/T.
• Corner Feed. Adaptive feed that holds chip load constant through inside and outside corners.
• Tool Deflection. Stick-out deflection and a banded chatter risk rating.
• Endmill Runout. TIR, per-flute imbalance and when to re-grip.
• Coolant. Mix concentration and nozzle jet velocity, with a chip-evacuation warning.

HOLES & THREADS
• Thread Data. NPT, UNC/UNF, UNJ/UNEF/UNM, Whitworth and Stub Acme: TPI, tap drill, clearance and countersink, with a taper cross section.
• Drill Sizes. Target diameter to the nearest standard drill, letter and number sizes.
• Tap Drill. Thread size to tap drill bit, with an anodize/plating allowance.
• Reaming. Pre-hole, stock, feed and speed.
• Countersink. Diameter and depth from the fastener.
• Center Drill. Standard sizes and 60° point depth.
• Fastener Reference. SHCS sizes and mounting holes.

LAYOUT & INSPECTION
• ISO Tolerance. Fit codes and limits from ISO 286-1 and ANSI B4.1 inch fits, with a tolerance zone drawing.
• True Position. Position tolerance with MMC/LMC bonus, plus a GD&T symbol reference.
• Bolt Circle. PCD, angles and chords, with a layout drawing.
• Gauge Block Stack. Which blocks of a standard set to stack for a target height.
• Height over Ball. Countersink and taper bore check with a precision ball.
• Hardness. Rockwell, Brinell, Vickers and Shore conversions.
• Thermal Expansion. ΔL = L·α·ΔT from the material's CTE.
• Angle. Degrees/min/seconds, arc geometry and conversions.
• Splines. Involute spline diameters, IS 3665 / ANSI B92.1 / SAE J499a.
• Knurling. Wheel pitch, teeth per rev and post-knurl diameter.
• Material Weight. Volume × density for bars, tubes and plates.

PROGRAMMING
• G & M Codes. Searchable CNC lathe G/M code reference.
• Hole Cycle G-code. G81-G84 drilling and tapping cycles over single, circular and rectangular patterns.
• Thread Programming. G84 rigid tapping, thread milling and G76 lathe threading.
• Scientific Calc. Trig, log, memory, DEG/RAD, with history.

LIVE DIAGRAMS
Every calculator draws its geometry as you type. Change the diameter and the cut setup redraws. Change the fit code and the tolerance zone rescales. The diagram is part of the answer, not an illustration.

BUILT FOR THE SHOP
• DRO-style readout. The main answer stays pinned at the top in a large monospace display, like a machine's readout.
• One-tap mm/in. Switch units on any screen and every value converts in place.
• Shared job context. Pick your work material and machine limits once, and every calculator uses them.
• History. Recent calculations are saved, so you can find a number and check it again.
• Home-screen widget. Pin the calculators you use daily and launch them in one tap.
• Dark and light themes, both designed for the shop floor.

VERIFIED DATA
The reference data is checked against published standards (ISO 286-1, ASME B1.1, IS 3665, vendor cutting data). Every record carries its source, so if a number is ever wrong, we can trace where it came from and fix it. A wrong value is a defect here.

PRICING
17 calculators are free. Pro is a one-time $7 purchase that unlocks the other 21. No ads, no subscription, no account.