Constant Amount Calculator
The same inflation-adjusted amount every year, regardless of how the market performs.
Part of the FIRE simulator, a historical backtest calculator that replays your plan across every rolling window of market history since 1871.
How the Constant Amount strategy works
The rule fixes a first-year withdrawal amount, for example 4% of the starting portfolio, then repeats that exact amount every subsequent year, grown only by realised inflation. This is the classic Bengen "4% rule" and the default most retirement studies benchmark against. The portfolio value never enters the calculation.
What the Constant Amount strategy trades off
Constant-amount withdrawals are the most predictable real income any of these rules produce, and the easiest to budget around. Nothing in the rule reacts to the market, so the portfolio absorbs a bad early sequence on its own, and a good one leaves money unspent.
Pros and cons
Pros
- Perfectly stable, predictable real spending
- Simple to understand and follow
- The most widely studied and benchmarked rule
Cons
- Ignores market signals, so it can deplete the portfolio in a bad early sequence
- Leaves large unspent balances in good sequences
- No mechanism to spend more when the portfolio grows
Parameters you can adjust
This strategy has no adjustable parameters. It runs from your portfolio, allocation, and starting withdrawal alone.
Backtest Constant Amount against market history
Opens the simulator with Constant Amount already selected, so you only set your portfolio and horizon.