How this calculator works
This calculator projects how a high-yield savings account (HYSA) can grow when you start with a balance, add monthly deposits, and earn a stated annual percentage yield (APY). It runs the same projection at a traditional savings rate so you can see the dollar difference—not just a rate gap—over your chosen time horizon.
Enter your starting balance, monthly contribution, HYSA APY, a comparison savings APY, and a horizon from one to thirty years. The results show projected HYSA balance, total contributions, interest earned, and estimated monthly interest near the end of the period. A second set of figures shows what the same deposits would earn at the regular savings rate, plus the extra interest the HYSA produces.
The chart plots both balances year by year. The table lists HYSA balance, standard balance, HYSA interest earned, and the cumulative edge versus the standard account. Shareable URL parameters restore every input so you can revisit or send a scenario without retyping numbers.
What APY means and why it matters
APY is the annual return after compounding. Most HYSAs compound daily and quote APY so shoppers can compare accounts without reverse-engineering nominal rates. This tool treats your entered APY as the effective annual yield and applies it in monthly steps (APY ÷ 12). That approximation tracks real daily-compounding math closely when you start from APY rather than a raw interest rate.
Always compare APY to APY. A slightly lower nominal rate with more frequent compounding can beat a higher-looking rate that compounds less often. Use the APR and APY converter if you only have a nominal rate and need to normalize before comparing offers.
How the comparison works
The regular savings APY defaults near a typical traditional-bank average so the gap is easy to see. Replace it with your current account’s APY for a personalized estimate. Both projections use the same starting balance, monthly contribution, and years—only the rate changes—so the “extra interest with HYSA” figure isolates the rate effect.
On a multi-year horizon with ongoing deposits, the gap compounds: each month’s higher interest becomes part of next month’s balance. That is why a few percentage points of APY can produce a large dollar difference even when both accounts are FDIC-insured and fully liquid. If you contribute $0, the tool still shows pure compound growth on the starting balance alone.
Variable rates and FDIC insurance
HYSA rates are variable. Banks adjust them as the Federal Reserve changes the federal funds rate and as competition shifts. This calculator holds rates fixed for illustration. If rates fall, future interest may be lower than shown; if rates rise, you may earn more. CDs lock a rate for a term; HYSAs keep liquidity and accept rate movement. For a product-level trade-off, see CD vs. high-yield savings.
Eligible deposits at FDIC-member banks are generally insured up to $250,000 per depositor, per insured bank, per ownership category. Credit unions offer equivalent NCUA coverage. Confirm insurance status before you move large balances, and spread amounts above the limit across institutions or ownership categories. Insurance protects against bank failure within coverage limits; it does not protect against inflation eroding purchasing power.
Common mistakes
- Comparing a promotional teaser APY to a long-term projection. Some offers drop after a few months. Model the ongoing rate you expect to keep.
- Ignoring fees and balance tiers. A monthly fee or a higher minimum to earn the top rate can wipe out the advantage on smaller balances.
- Treating HYSA returns like stock-market returns. A HYSA prioritizes liquidity and principal protection, not maximum long-run growth.
- Forgetting taxes. Interest is generally taxable as ordinary income in the year credited; a 1099-INT usually arrives if you earn $10 or more.
- Leaving cash above insurance limits at one bank. Split large balances if needed so each ownership category stays within coverage.
When to use this calculator
Use this tool when you are deciding whether to move cash into a HYSA, sizing an emergency fund that should earn a competitive APY, or comparing online offers against a brick-and-mortar savings rate. It is especially useful when you want a clear dollar answer to “how much more do I earn?” rather than only a rate comparison.
Pair it with the savings goal calculator when you need a monthly deposit to hit a target, the emergency fund calculator for months-of-expenses targets, the CD calculator when you are weighing a locked rate, and the compound interest calculator for more flexible compounding assumptions.
For a first-principles overview of HYSAs—how rates are set, how APY works, insurance limits, and what to look for when choosing an account—read What is a high-yield savings account?.
Related calculators
Project liquid savings growth and the HYSA-versus-standard gap with this tool. Convert nominal rates with the APR and APY converter. Estimate CD maturity value with the CD calculator. Work backward from a dollar target with the savings goal calculator.
FAQ
What is a high-yield savings account?
A high-yield savings account (HYSA) is an FDIC-insured deposit account that pays a significantly higher APY than a traditional bank savings account. HYSAs are typically offered by online banks and credit unions that have lower overhead costs.
How is APY different from interest rate?
APY (Annual Percentage Yield) reflects the true annual return including compounding. Most HYSAs compound daily, which slightly increases the effective rate above the nominal interest rate. Always compare APY rather than nominal rates when shopping accounts.
Is money in a HYSA safe?
Deposits at FDIC-member banks are insured up to $250,000 per depositor, per ownership category. Credit unions offer equivalent protection through NCUA. Verify the institution's insurance status before opening an account.
Why does the calculator use monthly compounding instead of daily?
Most HYSAs quote an APY that already accounts for daily compounding. When you enter the APY directly, the calculator divides it into monthly periods to project growth. The result closely matches actual daily-compounding math.
Can I use this for an emergency fund projection?
Yes. HYSAs are a common home for emergency funds — they earn more than traditional savings while remaining fully liquid. Enter your target months of expenses as the savings goal and set monthly contribution to your planned savings rate.
Why is the regular savings rate set to 0.50% by default?
The national average savings account rate at traditional banks is typically well below 1% APY. The 0.50% default is a representative benchmark; adjust it to match your current savings account if you want a personalized comparison.
Do HYSA rates change over time?
Yes. HYSA rates are variable and move with the federal funds rate set by the Federal Reserve. This calculator uses fixed rates for illustration. Actual results may be higher or lower if rates change during the projection period.
Should I move all my savings to a HYSA?
HYSAs work well for liquid savings — emergency funds, short-term goals, and cash you may need within a few years. For longer-term goals, investment accounts may offer higher expected returns, though with more risk. This calculator shows only the math; consult a financial professional for account recommendations.