Coast FIRE calculator
Coast FIRE is the point at which what you have already invested will grow, on its own, into enough to retire on at the age you have in mind — so from here on you only need to earn what you spend. Enter your age, your savings, the spending you want in retirement and a real return; the calculator gives the coast number today, how far you are from it, and when you would reach it if you keep contributing.
Arithmetic from your own inputs: no statutory data Runs in your browser — nothing you type is sent to this site's servers or to its analytics No sign-up Methodology and data status
- Coast FIRE number today
- $181,290
- Short of it by
- $81,290
- FI number at 65
- $1,000,000
- Today's savings at 65
- $551,602
| How it is built | |
|---|---|
| FI number: $40,000 ÷ 4.00% | $1,000,000 |
| Years of growth until 65 | 35 |
| Coast number: FI number ÷ (1 + 5.0%)35 | $181,290 |
| Retire at | Coast number today | Today's savings would grow to |
|---|---|---|
| 50 | $376,889 | $265,330 |
| 55 | $295,303 | $338,635 |
| 60 | $231,377 | $432,194 |
| 65 | $181,290 | $551,602 |
| 70 | $142,046 | $703,999 |
"Coasting" means no further contributions: the coast number is what, invested today at the real return, grows to the FI number by the retirement age. Everything is in today's dollars, so the return to enter is the return above inflation. The FI number does not allow for Social Security, a pension or taxes on withdrawals.
How the coast number is computed
- FI number = annual spending in retirement ÷ withdrawal rate. At 4%, that is 25 times spending; at 3.5%, about 28.6 times.
- Years of growth = retirement age − current age.
- Coast number = FI number ÷ (1 + real return)years. It is the present value of the FI number at the real return.
- If your invested savings are at or above the coast number you have "coasted": with no further contributions they are projected to reach the FI number on time. If not, the gap is shown, and if you enter annual contributions the calculator steps year by year — contributions added at the end of each year, growth on the balance — until the balance first exceeds that year's coast number.
The barista variant assumes part-time work in retirement covers part of the spending: the FI number is (spending − part-time income) ÷ withdrawal rate, and the coast number follows from it.
What the assumptions mean
- Real return. Everything is in today's dollars, so the return to enter is the return above inflation. US large-company stocks have returned about 6.8% a year above inflation since 1928 (about 6.9% since 1871); a 60/40 stock/Treasury mix about 5.1%; bonds and cash far less. The default of 5% is a planning figure with a margin below the all-stock history, and the result is very sensitive to it over long periods — try 3% and 7% as well.
- Withdrawal rate. The rate at which you would draw the portfolio in retirement. The safe withdrawal rate calculator shows what different rates imply for how long money lasts.
- Spending. Retirement spending is assumed to be flat in real terms. Social Security, a pension, taxes on withdrawals and healthcare before Medicare are not in the FI number; the withdrawal calculator handles the first three.
Statements on this page and their sources
Each sentence below states a fact the calculator does not compute. It was checked against the document named, most recently on 2026-09-10; the date is when to re-read it.
- US large-company stocks have returned about 6.8% a year above inflation since 1928 (about 6.9% since 1871); a 60/40 stock/Treasury mix about 5.1%; bonds and cash far less.
- Aswath Damodaran, 'Historical Returns on Stocks, Bonds and Bills: 1928–2025', histretSP.xls, sheet 'Nominal vs Real Data' — geometric mean of the real S&P 500 total return 1928–2025 = 6.77% a year; 60/40 with 10-year Treasuries 5.15%; T-bonds 1.45%; T-bills 0.28%
- Robert Shiller, online data (ie_data.xls) — real total return of the S&P composite, January 1871 to September 2023 = 6.92% a year; from January 1926, 7.02%