Coast FIRE Calculator Australia — Test Reduced Contributions
Test whether your portfolio can coast to financial independence with lower future contributions.
Coast FIRE is the point where compound growth alone can reach your retirement target — you just need to cover current expenses, without saving aggressively.
Coast FIRE is not really about a magic number. It is about answering a specific question: "Have I saved enough that compound growth alone can reach my retirement target, even if I stop contributing?" If the answer is yes, you can downshift to lower-paid work, reduce hours, or simply stop stressing about maximising your savings rate.
How Coast FIRE works
The concept is straightforward. If your portfolio is large enough today, and you give it enough time to compound at a reasonable rate of return, it will eventually reach your FIRE target — without any further contributions from you. The formula is:
Coast FIRE number = FIRE target ÷ (1 + return rate) ^ years until retirement
For example, if your FIRE target is $1,250,000, you expect a 7% nominal return, and you plan to retire in 25 years, your Coast FIRE number is approximately $1,250,000 ÷ (1.07)^25 = $230,000. Once your portfolio reaches $230,000, you are technically at Coast FIRE.
Coast FIRE targets by current age
Assuming a FIRE target of $1,250,000 ($50,000/year spending at 4% SWR) and a target retirement age of 60:
| Current age | Years to 60 | Coast FIRE number (7% return) | Coast FIRE number (5% return) |
|---|---|---|---|
| 25 | 35 years | $117,000 | $227,000 |
| 30 | 30 years | $164,000 | $289,000 |
| 35 | 25 years | $230,000 | $369,000 |
| 40 | 20 years | $323,000 | $471,000 |
| 45 | 15 years | $453,000 | $601,000 |
| 50 | 10 years | $635,000 | $767,000 |
Notice how much the target changes between 7% and 5% returns. This is why stress-testing matters — Coast FIRE depends entirely on compounding assumptions, and small changes in return rate create large differences in the required balance.
Coast FIRE vs Barista FIRE vs Lean FIRE
| Variant | Definition | Income needed? | Drawing from portfolio? |
|---|---|---|---|
| Coast FIRE | Portfolio will reach FIRE target through compounding alone | Yes, for current expenses | No |
| Barista FIRE | Partially FIRE, supplementing with part-time work | Yes, part-time | Yes, partially |
| Lean FIRE | Fully FIRE but on a lean budget ($30-40k/year) | No | Yes, fully |
| Fat FIRE | Fully FIRE on a comfortable budget ($80k+/year) | No | Yes, fully |
How to model Coast FIRE in this calculator
This calculator does not have a dedicated "Coast FIRE" mode, but you can model it effectively using staged contributions:
- Build your baseline — set your current savings rate and portfolio balance as scenario 1
- Create a coast scenario — save the baseline, then create scenario 2 with contributions dropping to $0 (or a minimal amount) after a certain number of years using staged contributions
- Compare — check whether the coast scenario still reaches FIRE within your acceptable timeline
If the coast scenario reaches FIRE only 2-3 years later than the full-contribution baseline, Coast FIRE is probably viable. If it adds 8-10+ years, you may not have reached the coast threshold yet.
Example: 35-year-old testing Coast FIRE
A 35-year-old with $200,000 currently invested, spending $50,000/year (FIRE target $1,250,000), and saving $25,000/year. The baseline scenario with full contributions might reach FIRE by age 52.
The coast scenario: keep contributing $25,000/year until age 40 (5 more years, reaching approximately $380,000), then drop contributions to $0. At a 7% return, the portfolio reaches $1,250,000 around age 57 — five years later than the full-contribution path.
The question becomes: is the freedom from aggressive saving between age 40 and 57 worth a 5-year delay in full FIRE? That is a personal decision, but the calculator makes the tradeoff visible.
Why staged contributions are essential for Coast FIRE
A single flat contribution number cannot model the Coast FIRE question. Coast FIRE is inherently about changing your savings behaviour at a specific point. Use the staged contributions feature to model 2-3 phases: an accumulation phase with high savings, then a coast phase with zero or minimal contributions.
What a good Coast FIRE result looks like
A good result is not just "technically reaches FIRE". It is a path that still looks acceptable when you stress-test with a lower return rate. If the coast scenario only works at 7% but collapses at 5%, the coast plan is too fragile to rely on. Test at least two return assumptions before deciding you have reached Coast FIRE.
Frequently asked questions
What is Coast FIRE?
Coast FIRE is the point where your existing investments are large enough that, even without additional contributions, compound growth alone will carry the portfolio to your FIRE target by your desired retirement age. After reaching Coast FIRE, you only need to earn enough to cover current living expenses — you no longer need to save aggressively.
How is Coast FIRE different from regular FIRE?
Regular FIRE means your portfolio can support your spending right now through withdrawals. Coast FIRE means your portfolio will reach that point in the future without further contributions, but you still need active income to cover expenses today. It is a milestone on the way to full FIRE, not a replacement for it.
What is the difference between Coast FIRE and Barista FIRE?
Coast FIRE means you have enough invested that compounding alone reaches your target — you just need to cover current expenses. Barista FIRE means you have partially reached FIRE and supplement your portfolio withdrawals with part-time work income. The key difference is whether you are drawing from the portfolio (Barista) or leaving it untouched to grow (Coast).
What return rate should I assume for Coast FIRE calculations?
Most Coast FIRE calculations use a long-run nominal return of 7% for equities. However, because Coast FIRE depends entirely on compounding over a long period, even a 1% difference in assumed returns changes the target significantly. Always stress-test with a lower rate (5-6%) to see how sensitive your Coast FIRE number is.
Can I reach Coast FIRE with superannuation?
Yes, super contributions count toward Coast FIRE if you are comfortable waiting until preservation age (currently 60) to access them. Many Australians reach Coast FIRE inside super earlier than outside it, because of the lower tax rate (15%) on super contributions and earnings.