$1,000 today is $3,870 in 20 years at 7%.
Full growth tables for a $1,000 starting balance: returns from 4% to 10%, horizons from 5 to 30 years, with and without monthly contributions — plus rule-of-72 doubling times.
How much will $1,000 grow in 20 years?
$1,000 grows to about $3,870 in 20 years at a 7% average annual return — 3.87× the starting amount. At 5% it reaches $2,653; at 10%, $6,728. Add $100 a month and the 7% outcome climbs to roughly $56,131. Returns are illustrative averages, not guarantees.
$1,000 left to compound, no additions.
| Annual return | 5 years | 10 years | 20 years | 30 years |
|---|---|---|---|---|
| 4% | $1,217 | $1,480 | $2,191 | $3,243 |
| 5% | $1,276 | $1,629 | $2,653 | $4,322 |
| 7% (headline) | $1,403 | $1,967 | $3,870 | $7,612 |
| 8% | $1,469 | $2,159 | $4,661 | $10,063 |
| 10% | $1,611 | $2,594 | $6,728 | $17,449 |
Annual compounding on the starting amount only, before taxes, fees, and inflation. Returns are illustrative assumptions, not predictions.
What $1,000 becomes when you leave it alone.
Compound $1,000 at 7% a year for two decades and it becomes $3,870 — 3.87× the original stake, with $2,870 of that being growth. The engine is compounding: each year's return earns its own return the next year.
Small differences in return compound into huge differences in outcome: at 4%, $1,000 reaches $2,191 in 20 years; at 10% it reaches $6,728. Three extra points from 4% to 7% is worth $1,679; the full jump to 10% is worth $4,536.
Add a monthly deposit and the curve bends up.
| Monthly addition | 5 years | 10 years | 20 years | 30 years |
|---|---|---|---|---|
| $1,000 alone | $1,418 | $2,010 | $4,039 | $8,117 |
| + $100/month | $8,577 | $19,318 | $56,131 | $130,114 |
| + $250/month | $19,316 | $45,281 | $134,270 | $313,109 |
| + $500/month | $37,214 | $88,552 | $264,502 | $618,102 |
7% annual return compounded monthly, contributions at each month's end. The $1,000-alone row differs slightly from the annual-compounding table above because of the monthly compounding convention.
Deposits first, compounding later.
Adding even modest monthly contributions transforms the curve. Put $100 a month alongside the $1,000 and the 20-year total at 7% jumps from $3,870 to about $56,131; at $500 a month it reaches $264,502. Contributions do the heavy lifting early, compounding takes over later.
How fast $1,000 doubles.
| Annual return | Years to double (72 ÷ rate) | Rule-of-72 estimate, 30 yrs | Exact value, 30 yrs |
|---|---|---|---|
| 4% | 18.0 years | $3,175 | $3,243 |
| 5% | 14.4 years | $4,238 | $4,322 |
| 7% | 10.3 years | $7,545 | $7,612 |
| 8% | 9.0 years | $10,079 | $10,063 |
| 10% | 7.2 years | $17,959 | $17,449 |
At 7%, money doubles roughly every 10.3 years — so a 20-year horizon fits almost two full doublings of $1,000.
Other starting amounts, 20-year view.
| Starting amount | At 5% · 20 yrs | At 7% · 20 yrs | At 10% · 20 yrs |
|---|---|---|---|
| $1,000 starting (this page) | $2,653 | $3,870 | $6,728 |
| $5,000 starting | $13,266 | $19,348 | $33,638 |
| $10,000 starting | $26,533 | $38,697 | $67,275 |
| $20,000 starting | $53,066 | $77,394 | $134,550 |
Annual compounding, lump sum only — click through for the full breakdown of any amount.
Chart any amount, rate, and timeline
The interactive compound interest calculator draws the full year-by-year curve for any starting balance, contribution schedule, and compounding frequency.
How these numbers are calculated.
Lump-sum tables use annual compounding: FV = P × (1 + r)ᵗ. The contribution table uses monthly compounding (r ÷ 12) with deposits at the end of each month, which is why its zero-contribution row runs slightly ahead of the annual table.
Return rates (4–10%) are illustrative long-run averages: 4–5% resembles high-yield savings/bonds, 7% a conservative stock-portfolio assumption, 10% the S&P 500’s long-run nominal average. Actual returns vary and can be negative.
All figures are nominal — before taxes, investment fees, and inflation, each of which reduces real-world outcomes.
Educational illustrations of compound-interest math — not investment advice or a forecast.