Compound Interest Calculator
See how an initial investment and daily contributions develop over 365 days.
Balance over 365 days
Daily calculations
| Day | Initial balance | End balance | Profit for the day |
|---|
Illustrative calculations based on a constant assumed daily return. Actual returns may vary, and losses are possible.
How to Use the Compound Interest Calculator
The Compound Interest Calculator allows you to explore how an initial investment can grow over time when profits are reinvested and additional contributions are made regularly.
Unlike a conventional compound interest calculator that uses an annual interest rate, this calculator works with a daily profit percentage and calculates the potential growth of your investment over 365 days.
It can be used to explore different investment, savings and trading scenarios.
Step 1: Enter Your Initial Investment
Start by entering the amount of money you want to invest.
For example, if you are starting with £1,000, enter 1000 in the Initial Investment field.
This is the starting balance from which the calculator projects future growth.
Step 2: Enter Your Daily Contribution
Next, enter the amount of money you intend to add to your investment each day.
For example, if you plan to contribute £5 per day, enter 5.
These additional contributions increase the amount of money available for future growth.
If you do not intend to make regular contributions, enter 0.
Step 3: Enter Your Expected Daily Profit Percentage
Enter the daily percentage return you want to investigate.
For example:
- 0.10% represents a daily return of one-tenth of one percent.
- 0.50% represents a daily return of half a percent.
- 1.00% represents a daily return of one percent.
The calculator applies your chosen daily percentage to project how your balance could grow through compounding.
Remember that this is an assumed rate of return, not a prediction or guarantee of future profits.
Step 4: Examine the Results
Once you have entered the three values, the calculator calculates the projected growth of your investment over 365 days.
The results allow you to examine how your initial investment, daily contributions and reinvested profits affect the final balance.
The key figures to consider are:
- Initial Investment: The amount you started with.
- Additional Contributions: The money added over the calculation period.
- Projected Final Balance: The total value after 365 days, assuming the selected daily return is achieved.
- Projected Profit: The growth attributable to the assumed returns, excluding your original investment and additional contributions.
Understanding Compound Growth
Compounding occurs when profits are reinvested rather than withdrawn.
For example, suppose you start with £1,000 and achieve a daily return of 1%, with no additional contributions.
On the first day, a 1% return produces £10, increasing your balance to £1,010.
On the second day, the same 1% return is calculated on £1,010 rather than the original £1,000.
This produces £10.10, increasing your balance to £1,020.10.
As the balance increases, the amount generated by the same percentage return also increases.
Over time, this compounding effect can become substantial.
Example: £1,000 at 0.5% Daily Growth
Suppose you enter the following values:
| Input | Amount |
|---|---|
| Initial Investment | £1,000 |
| Daily Contribution | £0 |
| Expected Daily Profit | 0.50% |
| Calculation Period | 365 days |
Assuming a constant daily return of 0.5%, with all profits reinvested and no withdrawals, the projected balance after 365 days would be approximately:
£6,174.65
This illustrates the mathematical power of compounding.
However, achieving a positive return of 0.5% every day for an entire year would be an extremely demanding assumption. Real investment and trading returns fluctuate, and losses can substantially reduce the final balance.
The calculator demonstrates what would happen if the assumed return were achieved consistently.
The Effect of Daily Contributions
Adding money regularly can make a considerable difference to the projected final balance.
For example, someone starting with £1,000 and contributing an additional £5 each day would invest a further £1,825 over 365 days.
These contributions increase the amount available to generate future returns.
The calculator combines regular contributions with compounding, allowing you to investigate how different savings and investment strategies might develop over time.
Experiment with Different Scenarios
One of the most useful features of the calculator is the ability to compare different assumptions.
Try changing your initial investment, daily contribution or expected daily return to see how each affects the projected balance.
You may find that relatively small changes in the daily percentage produce substantial differences over a full year.
This is because compounding magnifies the effect of percentage changes over time.
Important Points
- Enter the initial investment and daily contribution in pounds.
- Enter the expected daily profit as a percentage, not a decimal fraction.
- The calculator projects growth over 365 days.
- The calculations assume that the specified daily return is achieved consistently.
- Profits are reinvested rather than withdrawn.
- The projections do not guarantee future investment or trading performance.
- Actual results may be affected by losses, fees, taxes, withdrawals and changes in market conditions.
Why Use a Compound Interest Calculator?
Compound growth is not always intuitive, particularly when contributions are made regularly and profits are continually reinvested.
The Compound Interest Calculator makes it easier to understand how these factors interact over time.
It allows you to compare different starting balances, contribution amounts and daily return assumptions without having to perform the calculations manually.
Whether you are exploring a savings plan, modelling investment growth or investigating the mathematical effects of reinvesting trading profits, the calculator provides a straightforward way to examine the potential impact of compounding over 365 days.