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 4 September 2026

The sites we run

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

AmpSizer Wire size, voltage drop, breaker size and conduit fill from the published NEC tables — one answer with the wire, the breaker, the ground and the conduit in it. ampsizer.com 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 CalculatorMulch How much mulch, soil, gravel or sand you need: area and depth in — cubic yards, bags, tons and cost out, with a link you can send to the yard. calculatormulch.com CostRunning 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 DaysUntilNow Date calculators and live countdowns: days between dates, business days, week numbers, holiday dates and a countdown you can build yourself. daysuntilnow.com Devicedial Test your microphone, camera, keyboard, mouse, controller and screen right in the browser — no download, nothing uploaded. devicedial.com FlagDuel Live 1v1 click duels: reflex, speed, aim, focus and memory games against real players around the world. Free, no sign-up. flagduel.com TimerPlan Timers, stopwatch, clocks and time calculators that keep running when your screen goes dark — nothing to install, nothing uploaded. timerplan.com WheelJar Spin the wheel and let chance decide: random name pickers, coin flips, dice rollers, number generators and team makers — free, in your browser. wheeljar.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 If we cannot explain how a result was reached, we do not publish the tool.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.
Free, and not a trial
There is no paid tier, no account and nothing to buy. Advertising pays for the work and the tools stay free for everyone.

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. The calculators stay free either way, and there is nothing to buy: no accounts, no subscription, no paid tier.