WiseCalcs

Savings Calculator

Enter a starting deposit, a fixed monthly contribution, an annual rate you choose, and the number of years. The calculator shows the estimated end balance, the total paid in, and the interest in the estimate.

Written by Kenneth Schrøder, Founder of WiseCalcs

Updated ·Sources verified

This savings calculator estimates how a starting amount and monthly deposits could grow at a fixed rate you enter. It shows money paid in separately from interest.

USD
USD
%

Enter a whole number of years.

Estimated end balance

$41,872.85

Contributions Interest earned
Total paid in (initial deposit + monthly contributions)
$29,000.00
Interest in the estimate
$12,872.85

The estimate updates when you change an input. The bar compares the total you paid in (blue) with the interest in the projection (amber).

How does it work?

The calculator divides the annual rate by 12 and adds each monthly contribution at month end. The first contribution therefore earns interest from the next month. At 0%, the end balance is the starting deposit plus all monthly contributions.

Savings formula

FV=PV⋅(1+r)n+PMT⋅(1+r)n−1rFV = PV \cdot (1+r)^n + PMT \cdot \frac{(1+r)^n - 1}{r}
FV
Balance at the end.
PV
Starting deposit.
PMT
Amount added each month.
r
Monthly rate. The calculator turns 6% per year into 0.5% per month.
n
Number of months. Ten years means 120 months.

A $5,000 starting deposit with $200 added at the end of each month for 10 years, at 6% a year, grows to $41,872.85. You pay in $29,000, so $12,872.85 is interest.

Method & sources

This is a plan based on the four numbers you enter. It does not fetch a bank rate or allow for changes in the rate or monthly amount.

Sources

Where this method comes from — use these references to understand the formula, assumptions, and limits.

How we calculate

  • The calculator divides the annual rate by 12, so 6% a year becomes 0.5% a month.
  • Each monthly contribution is added at the end of the month.
  • The rate is a simple annual rate divided by 12. It is not an effective annual rate (APY), which already includes a year of compounding. To convert an APY, use: rate for this calculator = 1200 × ((1 + APY / 100)^(1/12) − 1). At 4.5%, the result is 4.40977..., so enter 4.41.
  • Taxes, fees, and inflation are not included.
  • The currency shown follows the site language; the maths is the same in every market.
  • When the annual rate is 0% the future value is simply the sum of all contributions.

Rounding

All monetary amounts are rounded to two decimal places when shown.

What the calculator estimates

The starting deposit earns interest for every month in the period. Each monthly contribution is added at the end of its month, so it earns interest only from the months that follow. The result is the estimated balance at the end of the chosen period.

How to use it

  1. Enter the initial deposit (or 0 if starting from scratch).
  2. Enter the amount you will add each month.
  3. Enter the annual interest rate as a percentage.
  4. Enter a whole number of years you plan to save.
  5. Read the future value, total contributions, and total interest earned.

An example

Suppose you start with $5,000 and add $200 at the end of each month for 10 years. At a 6% nominal annual rate, the projection is $41,872.85. You pay in $29,000 in total ($5,000 + $200 × 120), leaving $12,872.85 as interest. The monthly rate is 0.5%, and the payment made in month 120 has no time to earn interest before the period ends.

Assumptions to keep in mind

  • The calculator divides the annual rate by 12. So 6% a year becomes 0.5% each month. If an account shows a 4.5% effective annual yield, it becomes about 4.41% in this calculator. Enter 4.41, not 0.0441. The method section shows how to convert another effective annual rate. Your account may use a different way of adding interest.
  • The same rate and the same monthly contribution apply throughout the whole period. The calculation is a scenario, not a forecast of changing returns or deposits.
  • Taxes, account fees, and inflation are not included.
  • Try a few contribution amounts or time periods to compare scenarios, especially if you expect your saving amount to change.

When it is useful

It is useful for exploring a home deposit, emergency fund, retirement pot, or another goal with a time horizon and a regular monthly saving amount.

FAQ

How does compound interest work here?
Each month, interest is calculated on the balance at that point and added to it. In the next month, interest is calculated on that larger balance. That is compounding.
Is the rate nominal or effective (APY)?
The calculator divides the annual rate by 12, so 6% becomes 0.5% per month. An effective annual yield already includes compounding, so do not enter it directly. Use the method section to convert another rate. For example, 4.5% becomes about 4.41% in this calculator; enter 4.41. A real account may use a different interest schedule.
Are taxes and fees included?
No. The result does not include taxes on interest, account fees, or inflation.
What if I have no initial deposit?
Set the initial deposit to 0. The calculator works entirely from the monthly contributions.
Can I share a calculation?
Yes. The share button creates a link that opens the calculator with the same four inputs.

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