Coast FIRE Cheat Sheet

Find your age in the left column. Find your annual spending in the top row. The cell where they meet is your Coast FIRE number — the amount you need invested today for compound interest to carry you to full retirement by age 65. If your current portfolio equals or exceeds that number, you have reached Coast FIRE.

The baseline table uses a 10% nominal return minus 3% inflation minus 0% fees = 7% real return. The conservative table uses an 8% nominal return minus 3% inflation = 5% real return. Both assume a 4% safe withdrawal rate (Trinity Study) and retirement at age 65. The 7% baseline reflects 90 years of S&P 500 data.

The baseline table (7% real return) reflects the historical average of a broad US stock market index fund from 1926 to today. The conservative table (5% real return) represents a lower bound that has held true in virtually every 30-year rolling period in recorded market history. If your portfolio is mostly bonds rather than stocks, the conservative table is closer to your reality.

The formula is exact: Coast Number = FIRE Number / (1 + real return)^years. The uncertainty is in the inputs, not the math. Use the baseline table as your planning target and the conservative table as your safety margin. The real S&P 500 return has ranged from 5% to 9% across different 30-year periods, so both tables are within historical bounds.

These tables use fixed parameters (retire at 65, 4% SWR, 0% fees). If you want to retire at 55, have investment fees above 0.2%, or use a different SWR, use the interactive Coast FIRE Calculator on the homepage. It accepts custom inputs and shows three scenario projections in real time.