About PE-Calc
Built by a licensed Professional Engineer for working engineers, students, and contractors.
Why this site exists
The two big incumbents — Engineering Toolbox and LMNO Engineering — are great resources but show their age. Layouts are dated, ads are aggressive, and many calculators don't show the formula they apply or the coefficient values they assume. PE-Calc fixes those three things in every tool.
Design rules every tool follows
- Show the formula. Each calculator displays the equation it's solving and names every variable. No black boxes.
- Spell out coefficients. Manning's roughness, weir discharge coefficient, friction factor — these aren't constants. Every tool either accepts the coefficient as input or shows the value being assumed.
- Cite a reference. Engineering calculators get re-derived in textbooks every few years. Each tool cites the source equation (Chow, Brater & King, ASCE manual, etc.) so you can chase it back.
- Run client-side only. Inputs and results stay in your browser. Nothing is sent to a server.
Author
Built by a licensed PE based in the southeastern US. Day job is dam engineering and stormwater design. PE-Calc grew out of internal tools used on real projects and is being released for free, supported by ads.
Suggesting a tool
If there's a calculator you'd like to see prioritized, subscribe to the newsletter below and reply to any issue — tool requests are read and queued. The current backlog includes additional environmental, geotech, and structural calculators.