How long will it take for your savings to reach a target? Enter your current amount, the goal and the interest rate. The calculator returns the time in years and months, and the number of compounding periods after which the balance actually passes your target.
Time Period Calculator
Find how long it takes for savings to grow to a target amount.
Results are estimates for educational purposes and are not financial advice. Actual returns depend on your provider's terms, fees and taxes.
Time formula
t = ln(A ÷ P) ÷ [ n × ln(1 + r/n) ]
Taking natural logarithms of both sides of A = P(1 + r/n)nt lets us solve for t.
- t
- Time in years.
- A
- Target amount.
- P
- Starting amount.
- r, n
- Annual rate (decimal) and compounding periods per year.
- ln
- Natural logarithm.
Why two answers? The formula gives a smooth, continuous time. In a real account the balance only jumps on compounding dates, so the target is first reached at the next compounding date. The calculator shows both.
How to use
- Enter your starting amount and your target amount (the target must be larger).
- Enter the annual interest rate (must be above 0%).
- Select the compounding frequency and press Calculate.
Worked example
How long does $10,000 take to grow to $25,000 at 6% compounded monthly?
- A ÷ P = 2.5, and ln(2.5) = 0.916291.
- n × ln(1 + r/n) = 12 × ln(1.005) = 0.059850.
- t = 0.916291 ÷ 0.059850 = 15.31 years (about 15 years, 3.7 months).
- In whole months: 184 months, when the balance is $25,035.45.
With annual compounding it takes 15.73 years by the formula, so in practice 16 annual credits.
Practical uses
- Setting a realistic date for a savings goal.
- Seeing how much sooner you reach a goal with a better rate.
- Checking how long until an investment reaches a milestone.
Assumptions and limitations
- No additional deposits. Regular saving shortens the time considerably — model it with the regular contributions calculator.
- Constant rate; taxes and fees ignored.
- Very low rates can produce extremely long periods; results over 1,000 years are not shown.
Frequently asked questions
Can I solve for time with simple interest?
Yes, by hand: T = (A ÷ P − 1) ÷ (R ÷ 100). $10,000 to $25,000 at 6% simple takes 25 years.
What is the quickest way to estimate doubling time?
Divide 72 by the rate. For the exact figure, use the Time to Double Money Calculator.