What is APY Calculator?
A APY Calculator computes apy from the inputs you provide. It applies the standard formula to the values you enter and returns the result instantly, without sending any data to a server. Free, in-browser, no signup. The tool runs entirely.
APY Calculator
APY = (1 + rate/n)^n - 1. APR with compounding.
Inputs
APY
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Breakdown
About this tool
APY (Annual Percentage Yield) accounts for compounding; APR doesn't. The more frequent the compounding, the higher the APY. Daily compounding adds ~0.1-0.3% over annual. Continuous compounding (e^r) is the mathematical limit.
Under US Federal Reserve Regulation DD (Truth in Savings Act, 12 CFR Part 1030), every depository institution MUST disclose APY for savings/CD products, and APY must be calculated using a 365-day year (366 in leap years) with a uniform compounding formula. This means an apples-to-apples APY comparison across banks is legally enforceable. APR on the loan side (Reg Z / TILA) is a different beast: it includes fees but uses simple-interest compounding for the disclosure even when the underlying loan compounds monthly, which is why "APR" on a credit card understates the true cost of carrying a balance. In 2026 high-yield savings accounts at SoFi, Marcus, and Ally are advertising 4.0-4.5% APY, while top 1-year CDs hit 4.7-5.0% APY, both reflecting the higher-for-longer rate environment that followed the Fed pause cycle.
How it works
At 5% APR with annual compounding, APY = 5.000%. Monthly compounding lifts APY to 5.116%. Daily compounding to 5.127%. Continuous compounding caps at e^0.05 - 1 = 5.127%. Past daily, additional compounding frequency adds zero practical benefit – the diminishing-returns curve flattens. That's why the FDIC, RBI, and most regulators allow daily compounding to be marketed as "compounded daily" without forcing continuous-rate disclosure.
APY pitfalls
- Promo vs ongoing APY: Marketing materials often advertise the top-tier APY that requires hitting balance minimums, direct deposit triggers, or debit-card swipe counts. The "ongoing" or "base" APY can be 50-300 basis points lower. Always check the disclosure footnote.
- Tiered APY structures: Many banks pay higher APY only above a balance threshold (e.g., 4.5% on first $25K, 0.50% on excess). At a $50K balance, the blended APY is 2.5%, not the advertised 4.5%.
Frequently asked questions
Why does my bank statement show interest that doesn't match the APY exactly?
Because APY is the annualised effective rate, while monthly statements show interest accrued for that specific month at the daily periodic rate. For a 5% APY account with daily compounding, the daily rate is 0.0134%, so 30 days yields about 0.402%. Over 12 months, this compounds back to the 5% APY, but each individual statement reflects only the fraction earned in that period. Also: most banks credit interest on a calendar-day cycle (your "month" might be 28-31 days), and rates can change mid-cycle if the Fed moves between statements.
Is APY taxable as ordinary income?
Yes for US taxpayers. Interest from bank deposits, money market funds, CDs, and savings accounts is taxed as ordinary income at federal marginal rates (10% to 37% in 2026 brackets), reported on Form 1099-INT for amounts over $10. State tax applies separately except in states with no income tax (TX, FL, TN, WA, NV, SD, WY, AK). Treasury bills and notes are federally taxable BUT state-tax-exempt; municipal-bond funds are federally tax-exempt (and state-tax-exempt if from your home state). For a high-bracket investor, the after-tax APY of a 5% taxable savings account at 37% federal + 5% state is just 2.9% – a 4.0% muni bond often beats it on after-tax basis.
How accurate is the APY Calculator?
It applies the standard formula. Accuracy is limited only by your input precision. For decisions with material consequences (taxes, medical, legal, structural), use the result as a starting point and verify with a qualified professional in the relevant field.
Is the APY Calculator free to use?
Yes. 100% free, no signup, no payment, no API key. The site is funded by display ads around the tool but not inside the calculation flow.
Are my inputs saved anywhere?
No. All inputs stay in your browser tab. Closing the tab discards them. The site uses Google Analytics for traffic measurement (anonymized) but the analytics never see what you type into the form.
Can I use the APY Calculator on my phone?
Yes. The tool is responsive and tested on iOS Safari, Android Chrome, and major desktop browsers. Touch targets meet Apple's 44pt and Google's 48dp minimum.
Does the APY Calculator work offline?
Yes. Once the page has loaded, it works without internet. The calculation runs in JavaScript on your device.
How do I report a bug or suggest improvement to the APY Calculator?
Email hi@3tej.com with the URL of this page and a description of what you saw vs expected. We typically respond within 72 hours.
Can I share results from the APY Calculator?
Take a screenshot or copy the output. The page doesn't generate shareable URLs for specific calculations - inputs stay in your browser only.
Why are the results different from another apy tool?
Most likely: different formula assumptions, different default values, different rounding rules, or different applicable rates. Check the methodology if both tools document it. Both can be valid for different scenarios.
Is the APY Calculator accurate?
The APY Calculator applies the standard formula for apy. Accuracy is limited only by your input precision. For decisions with material consequences, use the result as a starting point and verify with a qualified professional or the relevant official source.
Is the APY Calculator free?
Yes. 100% free, no signup, no payment, no API key. The site is funded by display ads that appear around the tool but not inside the calculation flow.
Are my inputs saved?
No. Inputs stay in your browser tab. Closing the tab discards them. The site uses Google Analytics for traffic measurement (anonymized) but does not see what you type into the form.
How to use the APY Calculator
The APY Calculator is a browser-based tool that runs entirely on your device. Inputs you enter never reach a server - all calculations happen client-side in JavaScript. This means:
- Privacy: nothing is logged, sent, or stored by 3Tej. Inputs disappear when you close the tab.
- Speed: results update as you type. No network round trip.
- Offline use: once the page is cached, it works without internet.
- No signup: no account, no email, no rate limits.
Step by step
- Enter your inputs in the form above. Each field is labeled with its unit (currency, percent, kg, etc.) and the expected range.
- Read the result as it updates. The number reflects the formula commonly accepted in APY-related calculations.
- Adjust to see sensitivity: change one input at a time and watch how the output moves. This is the fastest way to understand which variable matters most.
- Copy or screenshot the result for later reference. The page state persists for the session if your browser allows it.
When you would use this
- Quick estimates: when you need a number now and don't want to open a spreadsheet.
- Sensitivity analysis: testing how a result changes as inputs vary, before committing to a real-world decision.
- Comparison: running the same calculation with different inputs to compare options side by side.
- Learning: building intuition for how the underlying math behaves.
- Documentation: capturing a snapshot of inputs and outputs at a point in time.
The formula explained
This calculator uses the following formula:
APY = (1 + APR/n)^n - 1; Continuous: APY = e^APR - 1
The reason this formula works is rooted in the underlying physics, finance, or biology of the problem. Behind every calculator is a published, peer-reviewed equation or a widely accepted convention. We do not invent formulas; we apply standard ones from textbooks, government tables, professional bodies, and academic literature.
If you are curious about the math, the simplest way to verify is to plug in two known numbers and compare against a known result. The calculator should match published examples to within rounding precision.