APY Calculator

APY calculator: compare interest rates the way banks want you to

If you’re shopping a savings account, CD, money market, or even a crypto “yield” promo, the headline number can be confusing. One offer says 4.50% APR, another says 4.60% APY, and a third talks about “daily compounding.” This APY calculator turns those details into a single comparable metric: effective annual yield.

What APY means (and why it’s different from APR)

APR (often called the “interest rate” or nominal rate) is the simple annual rate before compounding. APY includes compounding, which is what happens when the interest you earn starts earning interest too. The difference is usually modest, but when you’re comparing two offers that are close, APY is the cleaner apples‑to‑apples number.

In plain English: APR tells you the rate; APY tells you what you actually earn over a year at that rate and compounding schedule.

How this calculator works

Enter an APR and choose how often interest compounds (daily, monthly, quarterly, annually, or continuous compounding). The calculator first converts that into an APY. If you also enter a deposit amount and time horizon, it estimates your ending balance and total interest earned.

A simple way to interpret the results: if your APY is 4.60%, then $10,000 held for one year would end near $10,460 (ignoring taxes and changing rates). The ending balance output generalizes this for any time horizon you enter.

When APY is the right comparison tool (and when it isn’t)

APY is perfect for comparing products where the main difference is how interest accrues, like high‑yield savings accounts and CDs. It’s also useful when you’re trying to interpret marketing language that highlights “compounding frequency” to make a rate sound bigger.

But APY can be misleading if an account has tiered rates (different APYs for different balance ranges), intro periods (a high APY for 3 months), or conditional bonuses (APY only if you meet requirements). In those cases, treat APY as a starting point and read the fine print.

Examples you can copy (realistic comparisons)

• Savings account vs. CD: Compare the APY of a flexible savings account to the fixed APY implied by a CD’s rate and compounding. If you want to estimate CD growth directly, use our Certificate of Deposit (CD) Calculator.
• Monthly vs. daily compounding: Enter the same APR and switch the compounding frequency. You’ll usually see a small APY bump with more frequent compounding, helpful when rates are close.
• Longer horizon planning: Keep the same APY but increase the time horizon to see how compounding stacks over multiple years. For scenarios with regular contributions, use the Compound Interest Calculator.

Common mistakes (and how to avoid them)

• Mixing up APR and APY: If an account advertises APY and you treat it like APR, you’ll slightly overstate returns once you also apply compounding.
• Ignoring rate changes: Many savings APYs are variable. The calculator assumes a steady rate for the time horizon you enter.
• Forgetting taxes: Interest is often taxable. If you’re making a decision with a tight margin, think in after‑tax terms.
• Comparing different time windows: A promo APY might only apply briefly. Use the same time horizon for every option you compare.

What to do next

Once you have an apples‑to‑apples APY, the decision becomes simpler: pick the best yield that also matches your liquidity needs and risk tolerance. If you’re saving toward a goal, our Savings Goal Calculator can help you translate a rate and timeline into a monthly savings target. You can also browse the full library at /calculators/.

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