A savings scenario calculated with the settings below. Edit any value and select Calculate to update the estimate.
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Estimated final balance
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$484,827,245.28
3% daily interest on $10,000.00 for 1 year
- Starting balance
- $10,000.00
- Interest earned
- $484,817,245.28
Estimate from stated assumptions, not personal financial advice. Rates, fees, tax and account rules may change actual interest. Calculator disclaimer.
Yearly breakdown
| Year | Deposits added | Interest earned | Balance |
|---|---|---|---|
| 0 | $0.00 | $0.00 | $10,000.00 |
| 1 | $0.00 | $484,817,245.28 | $484,827,245.28 |
Assumptions used
- Effective annual yield
- 4,848,172.4528%
- This is a fixed-year mathematical projection, not a promise of a bank or investment return. Rates remain constant; fees, taxes and inflation are excluded.
- The entered 3% rate applies each day; it is not divided by the number of periods in a year.
- 1 week = 7 days; 1 model year = 365 days; 1 month = one twelfth of a model year. Thus 52 weeks is 364 days, slightly less than a year. This projection does not use calendar dates.
- Daily nominal compounding uses one-day intervals; weekly compounding uses seven-day intervals (365/7 periods per model year); monthly compounding uses 12 equal periods per model year.
- Regular deposits occur monthly, at the end of each modeled deposit period.
- Start-of-period deposits include a final partial period. End-of-period deposits occur only after complete deposit periods; a zero duration has no deposits.
- Interest between deposit events uses the equivalent growth factor for the elapsed fraction of a year. An effective annual yield already includes compounding.
- Year-end schedule entries include that period’s ending deposits, before the next period’s starting deposit. Monetary values are rounded only for display.
Currency: USD. Changing currency changes formatting only; no exchange-rate conversion. Values are rounded for display.
How compound interest works
Compound interest earns interest on your savings and on earlier interest. Regular deposits add to the balance earning interest.
Formula & worked example
With deposits, each deposit earns interest from its selected start or end time. In a partial final period, a start deposit is included when that period begins; an end deposit requires a completed period.
The projection uses a 365-day model year: a week is 7 days, and a month is 1/12 of a year. Weekly compounding happens every 7 days; monthly compounding uses equal months. So 52 weeks is 364 days. Partial periods use the equivalent fractional growth factor. Choose Days and daily compounding for a duration measured in days.
3% daily for one year
GBP 10,000 at 3% each day for 365 days, with no deposits, gives GBP 484,827,245.28: 10,000 × 1.03365. This is a constant-rate mathematical projection.
Compound interest with monthly deposits
Enter GBP 10,000, 1% nominal annual interest, Monthly compounding, and 1 Year. In Advanced options, select Nominal annual as the Rate basis. Under Add extra money, enter GBP 100 and Monthly. Deposit timing changes how long each deposit earns interest.
Scroll the table to see all amounts.
| Deposit timing | Deposits added | Interest earned | Final balance |
|---|---|---|---|
| End of period | 1,200.00 | 105.97 | 11,305.97 |
| Start of period | 1,200.00 | 106.98 | 11,306.98 |
The same GBP 1,200 is added in both cases. Start-of-period deposits earn one extra month of interest in this example. Choose the timing that matches when you add money.
Daily, weekly or monthly compounding?
Choose the compounding convention in your account’s terms. This model uses 365 daily periods, seven-day weekly periods or 12 equal monthly periods per year; it applies a fractional growth factor for a partial period.
With Nominal annual selected in Advanced options, GBP 10,000 at 5% annual interest over 1 Year, with no extra deposits, the final balance is GBP 10,511.62 monthly, GBP 10,512.46 weekly or GBP 10,512.67 daily.
At the same nominal rate, more frequent compounding increases this model’s result slightly. Changing the choice changes an assumption; it does not change the interest your provider pays.
Using APY or AER
If your provider quotes APY or AER, enter that percentage and select APY/AER as the Rate basis in Advanced options. For GBP 10,000 at 5% APY/AER over 1 Year, with no extra deposits, the model ends at GBP 10,500.00 for daily, weekly or monthly compounding. Adding compounding again would overstate the quoted yield.
Worked example: 1% annual interest compounded daily for 52 weeks earns GBP 100.22 on GBP 10,000 in this model.
Currency examples: US dollars ($) · British pounds (£) · Euros (€). Currency changes the display, not exchange rates.
Rates & assumptions
Per selected interval applies the entered percentage each day, week, month or year. For example, 3% with Daily means multiplying the balance by 1.03 each day. Nominal annual instead divides the yearly percentage by the number of compounding periods. APY/AER is an effective annual yield that already includes compounding; the calculator converts it to the equivalent periodic rate.
The model uses equal periods and a constant, non-negative rate. It does not model fluctuating investment returns or market losses.
Fees, tax, inflation, rate changes and bank crediting rules are excluded. Currency changes formatting only, with no exchange conversion. Results are estimates, not guaranteed returns or personal financial advice. Full disclaimer.
Privacy
With JavaScript, calculations run in browser memory. Without it, the native form sends values to Cloudflare for a temporary calculation. Values submitted with Calculate stay out of URLs and are not saved in a database, analytics or advertising. Intentional setting links include their chosen options and amounts; these addresses may remain in browser history and hosting request records. This app adds no tracking for those links. Server results are private, not cached or indexed.
Normal hosting requests still occur. This page has no advertising or analytics. The moon saves only your theme preference in this browser when storage is available. Without JavaScript, the theme applies to the current page.
If server calculation is unavailable, return to the calculator and retry later.
Contact & references
Made by IT1ST. Report errors to compound_interest_calculator@it1st.com using example values, without private account details.
References: CFPB annual percentage yield formula and interest accrual and compounding. Check your provider’s terms for its specific convention.