We got tired of it too.

Everything runs in your browser

There's no server crunching your mortgage numbers or logging your BMI. The calculations happen right on your device, the instant you type them. That's not a privacy claim we're making to sound good — there genuinely is no backend. Your data never touches our servers, because we don't have any.

Offline by design

Each tool is built as a PWA — a Progressive Web App — which means your browser caches it locally after the first visit. Lost signal on the underground? Your sleep calculator still works. Flying without Wi-Fi? Still fine. The tools are just there when you need them.

What the app remembers

Your recently used tools and your pinned favourites are stored locally in your browser — so when you come back, the things you use most are right at the top. That information never leaves your device, and you can wipe it any time by clearing your browser's site data.

The site is ad-supported and uses Google AdSense to show ads. Google may set cookies to personalise those ads based on your browsing history. See our Privacy page for the full breakdown, including how to opt out.

Who's behind this?

Pocket Multitool is built and maintained by one independent developer. No VC funding, no growth team, no dashboard tracking your every tap. Just a set of tools we actually use ourselves, put online in case they're useful to you too.

If something's broken, or you'd love to see a tool added, feel free to get in touch. We do read the messages.

How tools get chosen

A tool earns a place here only if it passes three questions. Is it a problem people hit every week or so, and not once a year? Is it a moment where a quick search or a chatbot is a worse answer, for example when you are standing in a shop aisle with one hand free, or offline? And does your phone's built-in calculator, clock or notes app fail to cover it? Tools that only explain a concept, with nothing to adjust or save, are left out.

The in-depth tools (Mortgage, Loan Payoff, Compound Interest, Unit Price, BMI, Calorie Calculator, Sleep Calculator, Hydration, Pregnancy, PawPortions, EV Charging Cost, Trip Fuel Cost, Salary Converter, Time Zone Planner, Image Converter, Random Picker, Secret Santa and the Christmas Countdown) each have a written guide under the tool that shows the formula, a worked example, and what the result does not cover. Simpler utilities are kept because they are useful, but they are not listed in search results until they have a guide of the same standard.

How the numbers are checked

The calculation code is kept separate from the screens, so it can be tested on its own. PawPortions, Secret Santa, EV Charging Cost, the Christmas Countdown and the image converters have automated tests covering the calculation code, for example checking that no Secret Santa draw ever gives someone their own name, and that day counts stay correct when clocks change. The worked examples in the guides are computed with the same formulas the tools use.

Tools are estimates, not advice. The health, pet and money tools say what they assume, and for anything that matters (a mortgage offer, a medical decision, a pet with a health condition) you should confirm with the lender, doctor or vet. Prices in the EV tool are examples you replace with your own.

How the site is paid for, and how we fix mistakes

The tools are free, with no paywall or account. The site is supported by ads from Google AdSense, which is why you see them. Ads have no influence on what the tools calculate or how they are written.

If something is wrong, tell us on the Contact page. Fixes, new tools and corrections are recorded with dates in the changelog.