About CalcuCalcu

CalcuCalcu is a collection of free online tools for everyday tasks: timestamp and case converters, image resizing and format conversion, color and meta-tag utilities, health calculators like TDEE and sleep cycles, random pickers and spin wheels, compound interest, and more. One site, no accounts, no installs — open a tool and use it.

Everything runs in your browser

Every tool on this site is built to work entirely client-side. The text you convert, the images you resize, the numbers you calculate — none of it is uploaded to a server. That makes the tools fast, keeps them working even on a flaky connection, and means your data stays on your device (see our Privacy Policy).

How we build the tools

Each tool uses standard, published methods: TDEE uses the Mifflin-St Jeor and Katch-McArdle equations, sunrise times use the NOAA solar calculation, UUIDs follow RFC 9562, and so on. Where a tool involves a formula or convention choice, we say which one we use on the page itself, so you can check our work instead of trusting a black box.

How a tool gets specified, sourced, tested and corrected is written up on our methodology page.

Limitations

These are practical everyday tools, not professional advice. Health calculators give standard estimates that vary by individual — consult a professional for medical or nutrition decisions. Financial calculators illustrate the math, not investment advice.

Who builds it

CalcuCalcu is written and maintained by D. Shin, who has spent roughly fifteen years in furniture manufacturing and in building the software around it — CAD automation, cut-list optimisation and production data pipelines. The same hands run our sister site RollCalculator, which covers trade and industrial calculations.

Most of these tools exist because we needed them ourselves: converting a timestamp out of a log, resizing a batch of photos without uploading them to a stranger's server, checking what a compound-interest quote actually implies. If a tool here feels like it was built by someone who uses it, that is why.

Tools that depend on a published equation or standard carry a note of which one, and the date the page was last reviewed. Corrections are credited and applied — see how we work.

The site is funded by advertising, which keeps every tool free. We take no payment for mentioning products, and no tool result is influenced by an advertiser.

Get in touch

Bug reports, suggestions and tool requests are always welcome — contact us and we'll get back to you. For a wrong result, include the tool and the exact inputs you used — that is usually enough to reproduce it the same day.