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APY savings growth

What will a balance earn at a stated annual percentage yield?

Your numbers

$
%
yrs
$

Ending balance

$32,664

Interest earned$3,464
Total contributed$29,200
Equivalent monthly rate0.355%

Tip. APY is not APR. Use the APY figure the bank prints on the account page.

Assumptions

  • APY already includes compounding; monthly rate = (1+APY)^(1/12)−1.
  • Optional monthly deposits at month end.

Explore the numbers

Examples and charts

Start with a scenario, then read the response curve to see which input actually moves the answer.

Example 1

Cash parked

No new deposits, just APY working on a starting balance.

Ending balance

$24,998

Example 2

Build and earn

The same balance with $200 going in every month.

Ending balance

$32,664

Example 3

After a rate cut

The same plan if the headline rate falls to 3%, which is what usually happens to promotional yields.

Ending balance

$31,560

Sweeps apy from half to one and a half times your value, holding everything else fixed.

Response curve

How apy moves the result

Ending balance

$32,664

$31k$32k$33k$34k3.0%4.0%5.0%6.0%
Chart axis: APYNow 4.3% → $33k

Timeline

Balance vs the money you put in
$0$10k$20k$30kNowY1Y3
  • Balance
  • Money you put in

What this calculates

Projects a savings balance using APY, which already accounts for the bank's compounding, plus optional monthly deposits.

How to use it

  1. Start with starting balance and work down the form, or load an example to begin from a realistic case.
  2. Read the headline result alongside the supporting rows, which show the intermediate figures behind it.
  3. Check the assumptions. They decide what the number includes and, more importantly, what it leaves out.
  4. Sweep apy on the response curve to see how much it actually moves the answer.
  5. Run a cautious case as well as an optimistic one before using the estimate in a decision.

Common mistakes

  • Entering an APR into the APY field, which understates the result.
  • Projecting a promotional rate across the whole horizon.
  • Comparing a savings APY to an investment return without noting that one is guaranteed and the other is not.

Formula

Monthly rate = (1 + APY)^(1/12) − 1, then compound with end-of-month deposits

Inputs

  • Starting balance
  • APY (%)
  • Years (yrs)
  • Monthly add

FAQ

Why convert APY into a monthly rate?

So that monthly deposits earn on the same schedule as the balance. Applying the annual APY to deposits made mid-year would overstate the interest.

Will my savings account really pay this for three years?

Almost certainly not. High-yield savings rates float and follow central bank policy, so treat a multi-year projection as a what-if rather than a forecast. Run the lower-rate example too.

Is the interest taxable?

In the US, savings interest is generally taxed as ordinary income in the year you earn it, so your after-tax growth is lower than what this page shows.

Are these numbers financial advice?

No. They are educational estimates based on the inputs and assumptions on this page. Confirm important decisions with a qualified professional and your own documents.

Read the full guideAPY vs interest rate

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