Tools
Controller tester: test your gamepad for stick drift
A free controller tester that runs in your browser: check every button, trigger and stick on a PlayStation, Xbox, Switch or PC controller, and test the sticks for drift.
Tools
Small calculators and converters that run in your browser. Use them here or copy the code.
Electronics
LED resistor calculator: what resistor for 12 V?
Work out the series resistor for an LED on 12 V, 5 V or any supply. Rounds up to a standard value and shows the current and the resistor's power.
3D Printing
3D print cost calculator: what prints really cost in the UK
A free calculator for the real cost of a 3D print in the UK, with filament prices, printer power figures and the maths shown.
Tools
How to write formulas on this site
Write maths in plain words and symbols and the site typesets it. Every example on this page, with what you type and what the reader sees.
Tools
Journey cost calculator UK: by number plate and postcode
Work out what a car journey will cost: type your number plate and two postcodes, or your own figures. Petrol, diesel or electric, one way or return, split between passengers.
Programming
Free QR code generator: static codes that never expire
Make free QR codes for links, Wi-Fi, email, phone numbers and texts. Static codes that never expire, with PNG and SVG downloads and code for your own site.
Tools
VAT calculator UK: add or remove VAT at 20% or 5%
Add VAT to a price or take it off at 20%, 5% or any rate. Shows the price without VAT, the VAT and the total, with the working.
Tools
Celsius to Fahrenheit converter, chart and gas marks
Convert Celsius to Fahrenheit or Fahrenheit to Celsius as you type, with the formula, quick mental methods, full charts and UK oven gas marks.
Tools
How to take VAT off a price: divide by 1.2
To take 20% VAT off a price, divide it by 1.2. Here is why it works, why taking 20% off gives the wrong answer, examples, the 5% rate and spreadsheet formulas.