Coast FI Calculator
Find out whether your current savings are already enough to “coast” to your retirement number through compound growth alone, or how far off you are.
Projected Growth vs Your FI Number
Your Coast FI Numbers
Year-by-Year Projection
Coast FI Calculator UK 2026
Our Coast FI Calculator shows whether your current invested savings, left alone to compound, are already on track to reach your retirement number — without you saving another penny. “Coast FI” (Coast Financial Independence) is the point where you can stop contributing and simply let time and compound growth carry you to your goal.
What Does “Coast FI” Actually Mean?
Coast FI is different from full Financial Independence. Reaching full FI means you already have enough invested to cover your living costs indefinitely, right now. Reaching Coast FI means something less demanding: your current pot, given enough years and a reasonable rate of return, is projected to grow into your full FI number by the time you plan to retire — even if you never add another pound to it. Many people who reach Coast FI keep working and earning, but with far less pressure to save aggressively, because their retirement pot is already “on autopilot”.
How to Use This Calculator
- Enter your current age and target retirement age — this sets how many years your savings have left to compound.
- Enter your current invested savings — pensions, ISAs, and other investments earmarked for retirement (exclude your emergency fund and property equity you plan to live in).
- Set your expected annual return — a real (after-inflation) return, typically 4–6% for a diversified portfolio.
- Enter your target annual retirement expenses — what you expect to spend per year in retirement, in today’s money.
- Set your safe withdrawal rate — commonly 4%, though some prefer a more cautious 3–3.5%.
- Optionally add your current monthly contribution to compare coasting against continuing to save.
- Click Calculate Coast FI to see your results.
How Your FI Number Is Calculated
Your FI number is your target annual retirement expenses divided by your safe withdrawal rate. For example, if you expect to spend £30,000 a year in retirement and use a 4% safe withdrawal rate, your FI number is £750,000 (£30,000 ÷ 0.04). This is the pot size that, at your chosen withdrawal rate, should theoretically sustain your spending without running out.
Coast FI Examples at Different Ages
| Current Age | Current Savings | Years to Retirement (65) | Projected at 65 (5%/yr) |
|---|---|---|---|
| 25 | £30,000 | 40 | £211,200 |
| 30 | £50,000 | 35 | £275,800 |
| 35 | £80,000 | 30 | £345,760 |
| 40 | £120,000 | 25 | £406,300 |
Illustrative only, using a fixed 5% real annual return with no further contributions. Actual returns vary and are never guaranteed.
Factors That Affect Your Coast FI Age
- Time horizon: The single biggest factor. Compound growth does most of the work over 20–40 year horizons, so reaching Coast FI early has an outsized effect.
- Rate of return: A higher assumed return shortens your projected Coast FI age, but also carries more risk and volatility. Using a conservative, realistic real return avoids overstating your position.
- Your FI number: Lower planned retirement spending (or a higher safe withdrawal rate) reduces the target you’re coasting towards.
- Retirement age: A later target retirement age gives your current savings more years to compound, making Coast FI easier to reach.
Frequently Asked Questions
Is Coast FI the same as being fully financially independent?
No. Full financial independence means you already have enough invested to cover your living costs today. Coast FI means your current savings are projected to grow into that full amount by your target retirement age, purely through compounding, without any further contributions. Many people who reach Coast FI continue working.
What return should I assume for this calculator?
Most long-term UK planning tools use a real (after-inflation) return of around 4–6% for a diversified equity-heavy portfolio, though actual returns vary year to year and are never guaranteed. A more cautious assumption gives a more conservative, less optimistic projection.
Does this calculator account for inflation?
The calculator uses a “real” rate of return, meaning the growth rate you enter should already be adjusted for inflation. Your annual expenses figure should be entered in today’s money terms. This keeps the whole projection in constant, comparable pounds.
What counts as “current savings” for Coast FI?
Generally, money you’ve earmarked for retirement and don’t plan to touch before then — pensions, ISAs, and other long-term investments. Most people exclude their emergency fund, and typically exclude the equity in a home they plan to keep living in, since it doesn’t generate withdrawable income in the same way.
What is a safe withdrawal rate and why does it matter here?
A safe withdrawal rate is the percentage of your retirement pot you plan to draw down each year. It directly sets your FI number: a lower withdrawal rate (more cautious) means you need a bigger pot for the same spending, which raises the bar for reaching Coast FI. This calculator lets you adjust it to see the effect.
Why is my Coast FI age higher than my retirement age?
That simply means your current savings, growing at the rate you’ve entered with no further contributions, aren’t projected to reach your FI number until after your chosen retirement age. It’s a signal that you’d need to keep contributing, increase your savings, extend your working years, or revisit your assumptions to close the gap.
Is this calculator financial advice?
No. This is a simplified planning illustration using a single fixed rate of return. It does not model market volatility, sequence-of-returns risk, changing contributions, or changes to your future spending. For a plan tailored to your circumstances, speak to a regulated financial adviser.