Barista FIRE Calculator UK: Calculate Your FIRE Number
Disclaimer
This post is not to be considered as financial advice or UK tax advice. This is for educational purposes only. Investment returns do vary and this is an illustrative example. When you invest your capital is at risk.
What this calculator does: Takes your current savings, annual expenses, target part-time income and expected return, and tells you the exact age you’ll hit Barista FIRE. It uses the 4% rule (adjustable for UK inflation) and compounds your monthly investments until you hit your target number.
New to Barista FIRE? Read my full Barista FIRE UK Guide first, then come back.
The guide covers how the maths works, UK tax wrappers (ISA and SIPP), and three worked examples.
If you already know what you’re doing, scroll down and plug your numbers in.
How to Use This Calculator
1. Enter your current age, savings and expected annual spend in retirement. Use your take-home pay (after tax and NI) as the starting point for expenses.
2. Add your target part-time income. This is what you plan to earn from semi-retirement work. Keep it realistic: typical UK Barista FIRE income is £8,000-£15,000/year.
3. Adjust the return and inflation assumptions if you want. The default return is 8% per year, based on the historical long-run average for global equities. Default inflation is 2.5% (Bank of England target). If you want a more cautious scenario, drop the return to 6% or bump inflation to 3%.
The output gives you your Barista FIRE number, the year you’ll hit it, and the monthly investment needed.
Understanding Your Result
Your Barista FIRE number is the total pot the calculator says you need invested.
It’s (annual expenses − part-time income) × 25, accounting for inflation.
The year you’ll hit it assumes you keep investing at the rate shown and your returns compound at the rate you set.
Markets don’t actually deliver steady returns year-on-year, so treat this as a midpoint estimate. The longer your timeline, the more reliable it is.
The monthly investment is what you need to put in each month to hit the number on the timeline shown.
If that number looks too high, you have three levers: extend the timeline, cut the target expenses, or raise the target part-time income.
Want the full explanation of how this maths works and why the 4% rule might need tweaking in a UK context?
Read my full Barista FIRE guide.
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