The only number I track monthly
For years I tracked net worth, category budgets, and a "fun money" envelope. All of it was noise compared to one ratio: what fraction of take-home pay didn't get spent.
| Savings rate | Years to independence |
|---|---|
| 10% | ~51 |
| 25% | ~32 |
| 50% | ~17 |
| 65% | ~10 |
The table assumes a 5% real return and withdrawing 4% a year. The exact numbers matter less than the shape: the lever is on the spending side, and every point of savings rate shortens the walk.
How I compute it
On the first of the month I write down last month's income after tax, then everything that left the account that wasn't a transfer to savings or investments. Fifteen minutes, one spreadsheet row. Apps kept wanting to categorise a coffee; I just need the total.