Savings Calculator
See how a lump sum grows over time at a fixed interest rate — no contributions, just growth.
What this calculator does
Shows how a one-time lump sum grows over time at a fixed interest rate, with compounding — no regular contributions, just the effect of your money earning interest, and that interest earning further interest. Enter your starting amount, rate, timeframe, and how often interest compounds, and it projects your final balance.
Who this is for
Anyone deciding between savings accounts or CDs/term deposits with different rates and compounding schedules, comparing a lump-sum inheritance or windfall's growth potential, or simply wanting to see the real difference between monthly and annual compounding over several years.
How this calculator works
Standard compound interest formula: A = P(1 + r/n)nt. More frequent compounding (monthly vs. annually) produces slightly higher returns for the same stated rate.
What each variable means
A = final amount, P = principal (starting amount), r = annual interest rate (as a decimal, so 4.5% = 0.045), n = number of times interest compounds per year, t = number of years.
Worked example
$10,000 at 4.5% annual interest, compounded monthly, over 5 years: A = 10,000 × (1 + 0.045/12)12×5 = 10,000 × (1.00375)60 ≈ $12,516. Compare that to annual compounding at the same rate: A = 10,000 × (1.045)5 ≈ $12,462 — monthly compounding earns about $54 more over 5 years on this example, a real but modest difference.
Principal vs. interest earned
Run the calculator above to see how much of your final balance is interest.
Common mistakes
- Assuming compounding frequency doesn't matter. It's a smaller effect than the rate itself, but monthly compounding does produce meaningfully more than annual compounding over long periods at the same stated rate.
- Not comparing APY across providers. Online high-yield savings accounts frequently pay several times what traditional brick-and-mortar banks offer for the same product — see Bank Interest Rates for current reference figures.
- Forgetting this is gross, not after-tax. Interest income is generally taxable, so your real take is somewhat lower than the figure shown.
- Confusing a savings calculator with a compound-interest-plus-contributions calculator. This tool models a single lump sum only — if you're adding money regularly (monthly deposits, for example), use the Compound Interest Calculator instead, which accounts for ongoing contributions.
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Frequently Asked Questions
Does compounding frequency really make a difference?
Yes, but a modest one — monthly compounding earns slightly more than annual compounding at the same stated rate, since interest starts earning interest sooner. The difference grows with longer time periods and higher rates.
What's the difference between this and the Compound Interest Calculator?
This calculator models a single lump sum with no further deposits. The Compound Interest Calculator adds regular ongoing contributions on top of a starting balance, which is the more realistic model if you're actively adding to savings over time.
Is this after-tax growth?
No, this shows gross interest earned. Interest income is generally taxable, so your actual after-tax growth will typically be somewhat lower.
What's a good savings account rate right now?
It varies by country and changes with central bank rate decisions — see the Bank Interest Rates page for current reference figures across several major economies.