Independent tool sites

Small tools that answer one question well

We build small, focused web tools and give them away. Every one of them answers a single question, runs in your browser, and shows its working. Ads pay for them, so you do not have to.

See our sites Why we build them

Updated 9 August 2026

The sites we run

Every one of them is free to use, needs no account, and shows how it got the number.

BTU Sizer Work out what size air conditioner, heater, fan, dehumidifier or extractor a room needs: floor area in, BTU, kilowatts, CFM and the nearest size sold out. btusizer.com Days Until Free live countdowns: exactly how many days, hours and minutes until Christmas, Halloween, Easter and every major holiday or season. daysuntilnow.com What It Costs Work out what any appliance costs to run: watts and hours in, cost per hour, day, month and year out — in your own currency and at your own price per kWh. costrunning.com

The rules every site here follows

It calculates before it asks for anything
No sign-up wall, no email gate, no trial. You land on the page, you get your answer. An account exists only if you want us to remember something or email you.
The method is on the page
Every tool shows the formula, the assumptions and where the numbers came from. If we cannot explain how a result was reached, we do not publish the tool.
Your data stays in your browser
The calculations run on your device. We store an email address only when you ask us to send you something, and deleting it deletes it — not deactivates it.
One subscription, never one per site
If you decide to pay, it covers every site we run today and every one we add later. We will not sell you the same thing twice under a different name.

Pro, if you want the ads gone

Pro removes the ads on every site we run, saves your setups across devices, emails you on your own dates, and turns any result into a page you can share or embed. $24 a year or $3.99 a month — one subscription, all our sites, including the ones that do not exist yet.

See what Pro includes

Why these sites exist

Most answers to everyday questions are one calculation away, and most of the places that offer that calculation make you work for it: a wall of text before the input, a form that wants your email, a result buried under three ads.

We build the other thing. One question per site, answered in the first screen, with the reasoning written underneath for anyone who wants to check it. The sites are small on purpose — a tool that tries to do everything ends up doing none of it well, and a page that loads in a second beats a page that impresses.

Ads pay for the work. If you would rather not see them, Pro takes them off everywhere we operate, and the calculators stay free either way.