What this calculator includes
- All spending, balances and contributions use today’s purchasing power.
- Nominal effective annual return, separate annual asset fee and exact inflation conversion.
- Explicit zero, negative-growth, already-reached and out-of-range results.
- Accessible growth chart, annual checkpoints and complete monthly CSV.
- Private in-tab inputs, currency labels without FX conversion, reset and print.
How to calculate your Coast FIRE number
- Enter current age, intended full retirement age and current invested retirement assets. Do not automatically include home equity or emergency cash.
- Enter annual retirement spending the portfolio itself must fund, in today’s money, plus a chosen withdrawal-rate assumption.
- Enter nominal effective annual return before the separately entered fee, then inflation. The tool converts to an exact fee-adjusted real growth factor.
- Read the zero-further-contribution threshold, funded ratio, shortfall or surplus and projected no-deposit retirement balance.
- Optionally compare a continued-contribution scenario. That comparison never changes the core zero-contribution Coast status. Keep earning enough for current living costs and revisit the assumptions.
Coast FIRE formula with fees and inflation
Full FIRE target F = annual portfolio-funded retirement spending ÷ withdrawal fraction. Let t be years from current age to chosen retirement age and g the effective real annual growth rate. Coast threshold today = F ÷ (1+g)^t.
The rate is g = [(1+nominal return) × (1−annual fee) ÷ (1+inflation)] − 1. This divides growth factors rather than simply subtracting inflation. The fee is a disclosed annual asset-fee model; real product fee timing may differ. Do not deduct the same fee twice when your assumed return is already net.
Zero remaining years gives the full target immediately. At zero real growth the Coast threshold also equals the full target. With negative real growth the amount needed today can exceed the retirement target. A Coast threshold is not always lower than FIRE.
Compare Coast FIRE targets at different ages
| Current age | Years to retirement | Required invested balance today |
|---|---|---|
| 35 | 30 | 231,377.45 |
| 45 | 20 | 376,889.48 |
| 55 | 10 | 613,913.25 |
| 65 | 0 | 1,000,000.00 |
The 5% input here is already a real-growth assumption. To reproduce it directly in this interface for a simple check, use 5% nominal effective return with zero fee and zero inflation. With nonzero fee/inflation, choose nominal assumptions that produce the intended real factor rather than entering 5% as both real and nominal.
Default example: age35, retirement65, assets200,000, annual portfolio-funded spending40,000, 7% nominal return, 0.25% annual fee, 2.5% inflation and4% withdrawal. Real annual growth is about4.1293%, the threshold is about297,040.39 and the current gap is97,040.39. No-deposit retirement balance is about673,309.12.
Keep the no-contribution result separate from extra savings
The core Coast test compares current invested assets with today’s discounted requirement. It assumes no further retirement contributions. The optional extra-saving line is a separate fixed-real end-month contribution scenario that runs to the retirement age. It does not retroactively mean that you can already coast without those deposits.
The chart shows no-deposit portfolio growth and the required Coast threshold at each future age. At the retirement date that required threshold converges to the full FIRE target. The CSV includes every month, the core path and the optional scenario when enabled.
Coast FIRE is not retirement today
Meeting a Coast threshold means the existing portfolio could reach the later target under the stated growth assumptions. It does not supply cash for food, housing, taxes or healthcare between now and retirement. Current spending still requires employment, a business or another funding source.
FIRE asks whether the full spending-based number can be accumulated with continued contributions. Barista-style semi-retirement introduces earned income and spending assumptions that this calculator does not automatically model. Use the separate FIRE tool for the continued-saving timeline.
Interpret a gap, surplus or already-met threshold
A positive gap is the additional invested amount needed today in this deterministic no-deposit scenario. It is not necessarily the amount you must contribute monthly. A surplus is modelled headroom, not proof that future living costs or market losses are covered.
If no portfolio-funded retirement spending is entered, the target is zero and the tool labels that assumption explicitly. If retirement age equals current age, the result becomes an immediate full-target comparison. A retirement age earlier than current age is rejected.
The separate continued-contribution comparison can show one way the future balance changes. It is not a guarantee, a recommended savings amount or a validated drawdown plan.
Stress the assumptions before reducing contributions
Review a lower return, higher inflation, higher ongoing cost or lower chosen withdrawal rate. These can substantially raise the amount needed now. Compare changing the retirement age as well; fewer years leave less time for growth when the real rate is positive.
Market sequence, taxes, healthcare, retirement length, asset access and changing spending are outside the fixed-rate accumulation model. No Monte Carlo probability, historical survival rate or guaranteed safe withdrawal rate is supplied. Consider these separately before changing a real retirement plan.
Use today’s-money spending with the real-rate result. Do not inflate that spending target a second time. An entered return already net of fees should not also be reduced by the same fee input.
Assumptions and limits
This is a deterministic accumulation model, not a drawdown simulation, market forecast, success probability or decision that you can retire. Enter nominal effective annual return before the fee entered here. The assumed annual asset fee reduces the post-return annual value: (1+return)×(1-fee). Inflation is then removed by division, not subtraction. If your rate already includes the same fee, enter zero extra fee to avoid counting it twice. Fixed-real monthly contributions are paid at month-end; their nominal amounts would need to rise with inflation. Portfolio-funded annual spending must include applicable retirement taxes, healthcare and other expenses you intend the portfolio to cover. Benefits, pensions, access restrictions, individual tax rules, changing spending and market-return sequences are not calculated. Home equity and emergency cash are not automatically counted as invested retirement assets. Currency labels do not convert values. Current inputs are memory-only and reset on reload. Bounds are support limits, not recommended return/withdrawal ranges.
Frequently asked questions
What is Coast FIRE?
It is the modeled point where your existing invested assets could grow to a future full retirement target without further retirement contributions. You still need income for current living expenses.
How is the Coast FIRE number calculated?
Divide the full spending-based FIRE target by the real growth factor raised to years remaining until retirement. Fees and inflation must use a consistent basis.
Can my Coast target be higher than the full FIRE target?
Yes. With negative real growth, more invested money can be required today to preserve a smaller future purchasing-power target. At zero real growth the two targets agree.
Do optional contributions change my Coast status?
No. Core Coast status always uses zero further contributions. Optional deposits are a separate comparison path only.
Does reaching Coast FIRE mean I can stop working?
No. It does not fund current living expenses or validate future withdrawal sustainability. It only compares an entered investment balance with a modeled future requirement.
Does this use the same assumptions as the FIRE calculator?
Both use the same real-rate and fee conventions. FIRE includes continued monthly saving toward the full target; Coast discounts the target under a no-further-contribution assumption.
Are example withdrawal and return rates recommendations?
No. They are editable arithmetic assumptions. Individual spending, retirement horizon, tax, fees and market outcomes can differ.
Method references
Compare continued saving with full FIRE
Full FIRE models the spending-based target and the first month it may be reached while you keep contributing.
Open FIRE calculatorExplore Pro plan comparisonsPublished by MyBreakeven. Method and examples checked . Business calculation methodology · Check scope and corrections.