Four Cents is a website dedicated to providing a convenient way to calculate how much petrol to pump when you’re using a per-litre discount. This solves a problem I often faced when pumping petrol: I have $40 to put in, but a 4c/L discount to be applied at checkout.. how much should I pump to reach $40.00 exactly? A small problem indeed, and one achievable with a calculator (but not very conveniently).

Any solution needed to be intuitive and quick to load; waiting for a bloated website/app to load while sitting at the service station wasn’t on. Therefore, the “back-end” is written in Javascript in a static/local manner. The website incredibly small (a few kB) and quick to load. The hosting is provided by GitHub Pages who provides static site hosting, and accelerated using CloudFlare’s free CDN to allow quick access worldwide.

The site itself has a simple design and provides an intuitive input steps to calculate the solution. Additionally, I included a calculation that determines at what price E10 fuel becomes cost-effective (this code can be seen here). This is based on the energy content in the fuel (as ethanol is less energy-dense than petrol), which is a relatively good approximation for the fuel’s possible Km/L (MPG). Of course, this still depends on the engine’s efficiency, and it doesn’t account for the environmental impact of ethanol fuel which can easily outweigh the few cents difference.

Summary

• Four Cents is a small, convenient website for calcuating fuel discounts and E10 cost effectiveness.
• It is static, local and its functionality is implemented in JavaScript.
• It uses custom CSS for a mobile-friendly and desktop-friendly design.
• It is reachable at: https://www.fourcents.me
• It’s code is available on my Github.