Compound interest calculator
A starting amount and monthly amounts growing at your assumed rate, compounded as you choose. Free, with no account or uploads.
Watch it compound
Type a starting amount, a monthly amount and the rate you assume.
Your own assumption: real returns go up and down.
If it grew at 7% every year
$54,714 after 10 years
$34,000 put in and $20,714 of growth. Real returns go up and down; this is the arithmetic of one steady rate.
At 7% money doubles in about 10.3 years by the rule of 72; exactly 10.2.
Show the numbers as a table
| Year | Put in | Growth |
|---|---|---|
| Year 1 | $12,400 | $801 |
| Year 2 | $14,800 | $1,834 |
| Year 3 | $17,200 | $3,115 |
| Year 4 | $19,600 | $4,662 |
| Year 5 | $22,000 | $6,495 |
| Year 6 | $24,400 | $8,633 |
| Year 7 | $26,800 | $11,100 |
| Year 8 | $29,200 | $13,918 |
| Year 9 | $31,600 | $17,114 |
| Year 10 | $34,000 | $20,714 |
A step-up: each year's monthly amount is this much more than the last.
A little help along the way
Follow these steps. Every option is explained underneath. Everything runs in your browser; nothing is sent anywhere.
- Say what you are saving withMoney each month, a lump sum, both, a fixed or recurring deposit, or taking money out.
- Type the amounts and a rateThe rate is your own assumption; real returns go up and down.
- Choose the yearsCommon lengths are one press away.
- Read the answerWhat it comes to, what you put in and what it grew by, and when it doubles.
Questions people ask
- How often is interest compounded?
- Monthly unless you choose yearly, quarterly or daily under More options; the rate is turned into an equal monthly one.
- What is the rule of 72?
- 72 divided by the rate gives roughly the years to double; the page gives the exact figure beside it.
- Is the rate a forecast?
- No. It is your own assumption; real returns go up and down.
This page is the Savings calculator, opened for this one job; every other tool it has is one press away. Each of its settings is explained on the Savings calculator's own page.
Read the step-by-step guide