We run a CAD comparison directory, and over time it grew a second life: a toolbox of 480+ free engineering calculators and utilities. Every one is a single static page that computes locally in your browser — no signup, no uploads, no ads between you and the number.
These are the ten our users reach for most, and a note on what each one is actually doing under the hood.
1. Beam Deflection Calculator
Standard structural mechanics: deflection for a beam under point loads, distributed loads, and your choice of support conditions. The inputs are load, span, and section properties; the output tells you whether that shelf, platform, or shaft will sag within spec.
2. K-Factor Bend Allowance Calculator
Sheet metal's favorite constant. Enter material thickness, bend radius, and angle; get bend allowance and the flat pattern length. If you're programming a press brake or unwrapping a part in CAD, this is the number that decides whether the flange lands where you meant it to.
3. Bearing Life Calculator
L10 basic rating life from dynamic load rating and equivalent load — the standard 90%-reliability figure bearing catalogs are built around. Useful when a vendor's catalog stops at "should be fine" and you need the hours.
4. Anchor Bolt Calculator
Anchor rod capacity and embedment checks for base-plate connections. The kind of calculation structural folks do twenty times a day and everyone else does once, badly, in a spreadsheet.
5. Arc Flash Calculator
Estimates incident energy for electrical safety boundary decisions. Not a substitute for a full arc-flash study, but exactly the right tool for a quick sanity check before someone opens a panel.
6. Air Duct Pressure Drop Calculator
Duct sizing and pressure loss for HVAC runs. Friction rate in, total pressure drop out — the number that settles the argument between the layout and the blower.
7. 3D Print Cost & Time Estimator
Material volume plus print parameters in, cost and hours out. Print farms use it for quoting; hobbyists use it to explain to their families why the printer runs all weekend.
8. Ball Screw Calculator
Lead, torque, and thrust relationships for ball screw selection. The difference between a axis that moves like butter and one that stalls halfway is usually this calculation done early.
9. ADA Ramp Slope Calculator
The 1:12 rule and friends, computed properly — run length, rise, and landing requirements for accessibility ramps. Architects and facilities people keep this one pinned.
10. Acoustic Decibel Calculator
Decibel addition and distance attenuation. One of those calculations that everyone does slightly wrong in their head (dB doesn't add linearly) and this page does exactly right.
The common thread
Every calculator above is a single static page. No signup, no file uploads, no server round-trip — the formula runs in your browser, so it works on confidential projects and costs nothing to operate. Each page also documents the formula it uses, because a calculator you can't verify is a calculator you shouldn't trust.
The full toolbox — 480+ calculators, converters, cheat sheets, and troubleshooting wizards — is at CADGuide.tools. Bookmark the ones you use; they'll still be there, and still free, next year.
If there's a calculation you can't find, tell us in the comments — the backlog is community-driven at this point.
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