About MultiConvers
MultiConvers is a free collection of calculators, converters and everyday tools. Simple tools. Instant answers.
The site exists so a conversion, a date calculation or a small utility can stay a short task: open a page, enter a value, get an answer. There are no accounts and no logins.
Why MultiConvers exists
Everyday questions — centimetres to inches, days between dates, electricity cost, formatting JSON — should not require a signup or a product to manage. MultiConvers is an independent place for those tools, kept simple and free to use.
Who runs MultiConvers
MultiConvers was created and is maintained by Andreas Rosenberg through AR Digital Services, an independent web development and IT services business based in Åland, Finland.
The site is independently developed. There is no larger company or editorial team behind it.
Andreas Rosenberg
AR Digital Services
Åland, Finland
Web development, IT services & digital solutions
How the tools are built
Accuracy, usability, privacy and mobile use matter when building each tool. Calculators and converters are tested and maintained as the site grows.
For calculators and converters, the formula or method is documented on the individual tool page where that is useful.
Many browser utilities transform text or data locally in your browser where that is technically possible. Production pages may still load anonymous analytics and advertising scripts; those scripts do not receive the values you type.
How formulas are chosen
A calculator page states the equation it runs. Where that equation is a published definition or a named paper — an SI conversion factor, a WHO adult BMI band, the Mifflin-St Jeor resting-energy equation — the page links the source. Prices, tariffs and activity levels are inputs you type. The site does not invent them.
A new URL is added when the question has its own method and its own limits. A reverse conversion stays on the same widget when the reverse is the same definition read the other way.
Corrections and updates
If a formula, unit or explanation is wrong, use the Contact page. The public address is hello@multiconvers.com. A fix is dated on the tool page when the explanation itself changes.
- — Source notes on defined formulas (BMI bands, Mifflin-St Jeor, the Navy tape method, NIST unit factors, kilowatt-hours, sample size and confidence intervals). Guides on what BMI measures and how L/100 km relates to MPG. Worked examples on the shortest Base64 and JSON guides.
- — Guides for units, percentages, markup versus margin, Pythagoras, averages, calendar days and electricity cost.
- — Guides for QR codes, passwords, JSON, Base64 and URL encoding.