Money Market Calculator

Formatting only. This does not change the calculation.
The lump sum already invested or deposited today. Use 0 if you are starting from nothing.
Banks advertise an APY, lenders a nominal rate. Say which one you typed in the field below.
Choosing APY converts the quoted yield back to the nominal rate its compounding schedule implies, so a full year returns exactly the APY you typed.
Amount added every contribution period. Leave at 0 for a pure lump sum.
Used only to restate the final balance in today's purchasing power.
Applied to the interest earned to show an after-tax balance. Use 0 for a tax-sheltered account.
Every figure is always computed; this only decides which one is presented as the answer.
Future value
11,248.64
Compound Interest Calculator
Total you put in
10,000.00
Of which contributions
0.00
Compound interest earned
1,248.64
Effective annual yield (APY)
4.0000 %
Equivalent nominal annual rate
3.928488 %
Multiple of what you put in
1.1249
Balance after tax on interest
11,248.64
Future value in today's money
11,248.64
Years for the balance to double
17.67
Average interest a year
416.21
Average interest a month
34.68
Worked out from Compound interest formula A = P(1 + r/n)^(nt), and the future value of an annuity FV = PMT[((1+i)^N - 1)/i] and 3 other sources.

How this is worked out

6 steps
  1. The 4% quoted is an APY, so the nominal rate behind it is 12 x ((1 + 4%)^(1/12) - 1) = 3.928488%.
  2. Rate per compounding period = 3.928488% / 12 compounding monthly (12 a year).
  3. Effective annual yield = (1 + r/n)^n - 1 = 4%.
  4. No recurring contributions, so the balance grows from the 10000 starting amount alone.
  5. Future value after 3 years = 11248.64, of which 1248.64 is compound interest on 10000 paid in.
  6. At this yield the balance doubles every ln(2)/ln(1+i) = 17.67 years.
Year-by-year balancetable
yearcontributionsinterestbalance
1040010,400
2041610,816
30432.6411,248.64

Results are general information, not financial, tax, legal, medical or engineering advice.