Calculator
Compound interest calculator
Watch contributions and growth stack. The chart is drawn from the same month-by-month series as the table, so the picture and the numbers cannot drift apart.
| Year | Contributed | Growth | Balance |
|---|---|---|---|
| 1 | $16,000 | $955 | $16,955 |
| 2 | $22,000 | $2,413 | $24,413 |
| 3 | $28,000 | $4,411 | $32,411 |
| 4 | $34,000 | $6,986 | $40,986 |
| 5 | $40,000 | $10,182 | $50,182 |
| 6 | $46,000 | $14,042 | $60,042 |
| 7 | $52,000 | $18,614 | $70,614 |
| 8 | $58,000 | $23,952 | $81,952 |
| 9 | $64,000 | $30,108 | $94,108 |
| 10 | $70,000 | $37,144 | $107,144 |
| 11 | $76,000 | $45,122 | $121,122 |
| 12 | $82,000 | $54,110 | $136,110 |
| 13 | $88,000 | $64,182 | $152,182 |
| 14 | $94,000 | $75,416 | $169,416 |
| 15 | $100,000 | $87,895 | $187,895 |
| 16 | $106,000 | $101,710 | $207,710 |
| 17 | $112,000 | $116,958 | $228,958 |
| 18 | $118,000 | $133,742 | $251,742 |
| 19 | $124,000 | $152,173 | $276,173 |
| 20 | $130,000 | $172,370 | $302,370 |
| 21 | $136,000 | $194,461 | $330,461 |
| 22 | $142,000 | $218,582 | $360,582 |
| 23 | $148,000 | $244,881 | $392,881 |
| 24 | $154,000 | $273,515 | $427,515 |
| 25 | $160,000 | $304,653 | $464,653 |
| 26 | $166,000 | $338,475 | $504,475 |
| 27 | $172,000 | $375,176 | $547,176 |
| 28 | $178,000 | $414,964 | $592,964 |
| 29 | $184,000 | $458,062 | $642,062 |
| 30 | $190,000 | $504,709 | $694,709 |
Shockingly Simple Math
A popular FIRE essay pointed out that the savings rate, not the cleverness of the portfolio, sets the calendar when you start from zero. The bars below are this site's version of that chart. You save the share on the left, spend the rest, and the target is 25 times that spending — a 4% withdrawal rate. The default return is 5% after inflation. Nothing is contributed from a balance you already have, because the point is the rate itself.
5% real return. Shorter bars mean fewer years of work.
At 5% real, a 50% savings rate is about 16 years in this model. A 10% savings rate is about 50. Fees, taxes, and a down market are not in the bars.
Reading the chart
The lower area is money you contributed. The upper area is growth. Early on, the lower area is most of the picture. Later, the upper area pulls away if the rate is positive and the horizon is long. Hover or move across the chart for a single year. The table under it is the same series, which is the version a screen reader can walk.
The default — $10,000, $500 a month, 7% monthly, 30 years — is an illustration that finishes near $695,000. It is not a forecast and not a suggestion to invest at that rate.
Read how the formula works · Use your own income
Questions
How does this calculator compound?
Each month the contribution is added. At the end of each compounding period the balance is multiplied by one plus the annual rate divided by the number of compounds per year. Monthly is the default. Annual compounding on a lump sum matches principal times (1 + rate) to the years.
What is the Shockingly Simple Math section?
It charts years to financial independence against savings rate, starting from zero. Spending is the unsaved share of income. The portfolio target is that spending divided by 4%. The default return is a 5% real return. A popular FIRE essay used this relationship to argue that savings rate dominates the calendar. The chart here is our calculation of that idea, not a copy of the essay.
Are taxes and fees included?
No. Lower the rate by an expense ratio if you want a net illustration. Taxes on interest, dividends, and gains depend on the account and are not in the chart. A workplace plan and a taxable account with the same pre-tax return do not finish in the same place.