Interest Savings Calculator

Display currencyFormatting only. This does not change the calculation.

Starting amount The lump sum already invested or deposited today. Use 0 if you are starting from nothing.

Annual interest rate (%)Banks advertise an APY, lenders a nominal rate. Say which one you typed in the field below.

The rate above isChoosing APY converts the quoted yield back to the nominal rate its compounding schedule implies, so a full year returns exactly the APY you typed.

Time invested (years)

Compounding frequency

Regular contribution Amount added every contribution period. Leave at 0 for a pure lump sum.

Contribution frequency

Contributions are made

Inflation rate (%)Used only to restate the final balance in today's purchasing power.

Tax rate on interest (%)Applied to the interest earned to show an after-tax balance. Use 0 for a tax-sheltered account.

Include the year-by-year table

Compound interest earned

834.56

Compound Interest Calculator

Future value

7,834.56

Total you put in

7,000.00

Of which contributions

6,000.00

Effective annual yield (APY)

4.0000 %

Equivalent nominal annual rate

3.928488 %

Multiple of what you put in

1.1192

Balance after tax on interest

7,834.56

Future value in today's money

7,834.56

Years for the balance to double

17.67

Average interest a year

166.91

Average interest a month

13.91

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

7 steps

The 4% quoted is an APY, so the nominal rate behind it is 12 x ((1 + 4%)^(1/12) - 1) = 3.928488%.
Rate per compounding period = 3.928488% / 12 compounding monthly (12 a year).
Effective annual yield = (1 + r/n)^n - 1 = 4%.
100 added monthly (end of period) over 5 years totals 6000.
Future value after 5 years = 7834.56, of which 834.56 is compound interest on 7000 paid in.
Interest accumulated = ending balance - everything paid in = 7834.56 - 7000 = 834.56.
At this yield the balance doubles every ln(2)/ln(1+i) = 17.67 years.

Year-by-year balancetable

year	contributions	interest	balance
1	1,200	61.84	2,261.84
2	1,200	112.32	3,574.16
3	1,200	164.81	4,938.97
4	1,200	219.4	6,358.38
5	1,200	276.18	7,834.56

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