Name the target and the date you want the money ready. The calculator will tell you what to save each month. If you already have a monthly amount in mind, enter it too; you will see whether it is enough, and by how much. Already know the most you can save each month? Use timeline mode to see how long the target may take.

Use one currency throughout. The tool rounds figures to two decimal places. For currencies split into anything other than hundredths, the result needs an extra rounding adjustment. Your entries stay in this page's memory and are cleared when you reset or leave. There is no account connection or email gate.

Choose the annual-rate setting before you calculate

The tool has two ways to turn an annual rate into a monthly rate.

  • Choose effective annual rate when the displayed annual rate already includes the effect of compounding over a year. US APY and UK AER are common examples, though local definitions differ.
  • Choose nominal annual rate only when the provider states that the annual rate should be divided by 12 for a monthly projection.

The distinction changes the answer.

US APY is an annualized savings rate that reflects the interest rate and frequency of compounding. The current formula and assumptions are in Regulation DD's Appendix A. That makes the effective-rate setting the closer simplified match for an APY. It still will not reproduce a bank's daily balance, crediting, tier, fee, or rounding rules.

If the account documents do not make the convention clear, run the plan at 0% first. That gives you a contribution-only baseline without inventing interest.

How both modes work

For an effective annual rate a, the calculator uses:

monthly rate = (1 + a)^(1/12) - 1

For a nominal annual rate, it uses:

monthly rate = a ÷ 12

At the end of each modeled month, the tool calculates interest on the balance and rounds that interest to two decimal places. It puts the rounded interest into the balance before adding that month's contribution.

In deadline mode, the calculator finds the smallest contribution, in increments of 0.01, that reaches the target after the selected number of months under the declared rounding model.

At 0% interest, you can check the deadline result by hand:

monthly contribution = (target - current savings) ÷ deadline months

Round that amount up to the next hundredth. When interest is included, the calculator tests contribution amounts in increments of 0.01 against the same month-by-month projection. It also projects your planned contribution through the deadline. The difference between those two monthly amounts is the gap or cushion.

In timeline mode, the calculator repeats your planned contribution until the target is reached or the projection ends. The final full contribution is not reduced when it takes the balance above the target.

Worked deadline example

Priya and Elena already have 3,000. Their target is 15,000, 24 months away. They expect to put aside 450 each month and choose the 4% effective annual rate setting.

Using (1.04)^(1/12) - 1 gives a monthly rate of about 0.327374%.

With interest rounded monthly and contributions added at month end, the calculator requires 471.62 a month and ends at 15,000.24 after 24 months. Their planned 450 a month ends at 14,461.32, so the monthly gap is 21.62.

The projection estimates 681.36 of interest at the required contribution. At 0%, the 12,000 gap divided by 24 months would need 500 a month. The rate reduces the modeled contribution, but it does not make 450 enough.

A pass-or-fail result would hide the useful number: 21.62. Priya and Elena could cover that monthly shortfall, give themselves more time, trim the target, or use timeline mode to find out where 450 a month takes them. When the planned contribution is above the required amount, the result labels the difference as a monthly cushion.

Use timeline mode when the contribution is fixed

Choose the second mode when you know what the household can save each month but the finish date is flexible. It reports the first month the target is reached, total contributions, estimated interest, and the ending balance after the final full contribution.

Run it at 0% as a contribution-only baseline, then add the account's stated rate using the correct convention. For a short goal, this comparison often shows that a sustainable contribution matters more than a small rate difference.

Use three runs for the conversation

Start with a baseline you could repeat in an ordinary month. Then change one input at a time.

  1. Calculate the contribution for the deadline at 0% to see the contribution-only requirement.
  2. Add the account's stated annual rate using the correct convention.
  3. Compare the required amount with a contribution that still leaves room for ordinary life.

Do not let the shortest date win by default. Ask which contribution each person can sustain, whether the goal needs a separate access rule, and what happens during a low-income month. If contributions will differ, record the shared monthly total here and keep the agreed individual amounts in your own plan.

Try this sentence:

"I can see what moves the date. Which monthly amount would still feel possible in a difficult month?"

A shared savings plan can turn that answer into a contribution rule. For a goal within roughly a year, the short-term financial goals guide helps define the target and finish line.

Reasons your real balance will differ

Savings providers may calculate interest daily, use balance tiers, apply conditions, change rates, charge fees, or credit interest on a different schedule. Tax treatment and product protection also vary by place and account. Check the current account terms before treating the projected interest as expected earnings.

The calculator repeats a fixed contribution and fixed annual rate. It excludes fees, tax, withdrawals, missed or irregular contributions, and changing rates. If a long, high-growth projection exceeds the tool's supported currency precision, it returns an error instead of displaying a false-precision balance. It cannot choose the target, predict an account balance, or say whether the goal should outrank debt, emergency savings, or current household needs. The high-yield savings explainer covers the product questions without turning this calculator into an account comparison.