My name is Daniel Müller. I am a mechanical engineer and have worked as a development engineer, design engineer and project engineer in special purpose machinery; today I head the design department at a special purpose machinery company. The calculations on this site are the same ones I use and need in my own work.
It started as a collection of my own Excel spreadsheets. One file per recurring calculation, one sheet per standard, and more of them every year. What bothered me was not the effort but the uncertainty: after six months I often could no longer tell which assumption sat behind a given cell, or against which source I had checked it at the time.
That is exactly what is better here. The calculators name the standard or reference work they follow, show the calculation path and state the limits of application. A large part is additionally verified against worked examples from the literature. What that looks like in detail is described under method and quality assurance.
The calculators are free to use in the browser. If you would like to support the project and my work, and want access to the export documents and verification PDFs, you can unlock a single calculator with a one-off payment or take a subscription.
Feedback from people in mechanical engineering doing the same kind of sizing work is very welcome - it is what makes the project broader and better. Get in touch.