How I Built a GST Calculator with AI: Lessons from a Beginner-Friendly Project

As developers (and learners), we’re often told that the best way to grow is to build something useful. Recently, I decided to put this advice into practice by creating a simple GST (Goods & Services Tax) Calculator — with a twist: I let AI (ChatGPT) guide me through the build.

At first, the idea felt intimidating. I don’t consider myself a finance or tax expert, and my coding knowledge is still a work in progress. But what I discovered is that combining curiosity with AI support can turn a small idea into a working project much faster than expected.

Why a GST Calculator?

In Australia, GST applies to most goods and services at a rate of 10%. For small business owners, freelancers, and even everyday shoppers, it’s handy to quickly calculate GST-inclusive or GST-exclusive prices. I figured a lightweight calculator would be a practical tool to build — not too complex, but still impactful.

How AI Helped Me Build It

Breaking Down the Logic
ChatGPT helped me outline the formula:
GST = (price × 10%)
Price including GST = price + GST
Price excluding GST = price ÷ 1.1

Writing Clean Code

I asked AI to generate snippets in JavaScript and Python.
Then I refined the UI for simplicity — just input fields, a button, and a results area.

Iterating with Prompts

Each time I hit an error or formatting issue, I went back to ChatGPT with specifics.
The loop of try → test → refine became the fastest debugging process I’ve ever used.

Deployment & Usability

I used a lightweight framework to host it online.
Focused on making it mobile-friendly so anyone can calculate on the go.

The Final Tool

You can try it here: Online GST Calculator

It’s simple, but it works — enter a price and instantly see the GST and final totals.

What I Learned

• Start small: A tiny project teaches real lessons in logic, debugging, and deployment.
• AI is a great mentor: Not perfect, but incredibly helpful for breaking through roadblocks.
• Sharing matters: By publishing the project, I’m accountable to improve and open to feedback.

What’s Next?

This project gave me the confidence to explore more AI-assisted builds. I’m considering:

• Expense trackers
• Multi-currency tax tools
• Budgeting dashboards

If anyone here has tried building small tools with AI guidance, I’d love to hear your stories!