Calculate compound growth with monthly contributions, adjustable compounding frequency, and annual deposit increases.
USD inputs · transparent calculation assumptions
Instant updates as inputs change
Data is calculated in this browser only
USD inputs · transparent calculation assumptions
Future balance$31,998.32
Total contributions
$22,000.00
Interest earned
$9,998.32
Effective annual yield (APY)
5.12%
Principal-only doubling time
13.89 years
Calculation notes
Understand the Compound interest calculator
For nominal rate a and n compounds per year, effective monthly return = (1 + a / n)^(n / 12) − 1. Grow the balance each month, then add that month’s deposit; increase deposits at each year boundary. The calculation runs locally and keeps cash-flow timing consistent with the stated assumptions.
Formula and logic
How does compounding frequency affect monthly investment deposits?
For nominal rate a and n compounds per year, effective monthly return = (1 + a / n)^(n / 12) − 1. Grow the balance each month, then add that month’s deposit; increase deposits at each year boundary.
Worked example
How much does $10,000 earn in one year at 5% compounded monthly?
With $10,000 initially, 5% nominal interest compounded monthly, and no deposits, one year ends near $10,511.62. Monthly deposits of $100 add $1,200 principal plus their accrued growth.
How to read the result
How is effective annual yield different from nominal interest?
APY differs from nominal APR when interest compounds more than once a year.
The doubling time is for principal alone; additional deposits make the account balance grow differently.
Limits and assumptions
Are deposits added at the beginning or end of each month?
Constant rates are hypothetical. Taxes, fees, variable returns and beginning-of-month deposits are excluded. Monthly deposits use an equivalent monthly rate for the selected compounding frequency.