Compound Interest Calculator

Select how often the interest should be added to your principal balance. Monthly compounding is common and can yield better returns than annual compounding. More frequent compounding means more interest accrues over time.
If you plan to add more money regularly, enter that amount here. For example, if you can add £100 each month, enter 100. Regular contributions can significantly increase your future balance.
Choose how often you will make additional contributions to your investment. Monthly contributions are common and manageable for many people. Frequent contributions can help your investment grow faster.

Future Balance

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Breakdown of Your Deposits and Interest (Cumulative)
Year Deposit Interest Ending Balance

Frequently Asked Questions

1. What is compound interest, and how does it work?

Compound interest is interest calculated on both the initial principal and the accumulated interest from previous periods. This results in exponential growth over time as interest is earned on a growing balance. The more frequently interest is compounded, the greater the effect.

2. How does a compound interest calculator help me?

A compound interest calculator allows you to estimate how much your investment or savings will grow over time, factoring in interest rates, the frequency of compounding, and any additional contributions. It helps you visualise potential returns, making it easier to plan for financial goals like retirement or large purchases.

3. What are the differences between simple and compound interest?

Simple interest is calculated only on the principal, while compound interest is calculated on the principal plus any interest earned. Compound interest grows faster because each period's interest is added to the balance before calculating the next period's interest.

4. How do I calculate compound interest?

To calculate compound interest, use the formula:
A = P ( 1 + r n ) n t

  • A is the amount of money accumulated (including interest),
  • P is the principal amount,
  • r is the annual interest rate,
  • n is the number of times the interest is compounded per year, and
  • t is the number of years.

5. What is the best compounding frequency for my savings?

More frequent compounding (daily or monthly) generates more interest than less frequent compounding (quarterly or annually). However, the difference becomes more significant over longer periods or with higher interest rates.

6. How does compound interest affect my investments?

Compound interest accelerates the growth of your investments over time. The longer you invest, the more your interest earns additional interest, leading to greater returns, especially when combined with regular contributions.

7. What's the difference between daily, monthly, and annual compounding?

The main difference lies in how often interest is applied. Daily compounding means interest is added every day, whereas monthly or annual compounding adds interest at the end of each month or year. More frequent compounding generally results in higher returns over time.

8. Can I calculate the future value of regular contributions?

Yes, compound interest calculators can include regular contributions (e.g., monthly savings). This allows you to see how much your total investment will grow when you contribute a fixed amount over time.

9. How do UK taxes affect compound interest?

In the UK, taxes on interest income (such as from savings accounts) can reduce your returns. Using tax-efficient accounts like ISAs (Individual Savings Accounts) allows you to earn interest tax-free, maximising the benefits of compounding.

10. How long should I invest to benefit from compound interest?

The longer you invest, the more you benefit from compound interest. Even small investments can grow substantially over decades. Time is a key factor in maximising compound returns.

11. How does inflation impact compound interest?

Inflation reduces the purchasing power of your returns over time. To account for inflation, consider investments with returns that exceed inflation or use real returns (adjusted for inflation) when calculating compound interest.

12. How can compound interest help with retirement planning in the UK?

Compound interest can significantly increase your retirement savings. By investing early and regularly in tax-efficient accounts like ISAs and pensions, you can take advantage of compound growth to build a larger retirement pot.

13. Can I use a compound interest calculator for mortgages or loans?

Yes, compound interest calculators can also be used to understand the interest accumulation on loans or mortgages, helping you plan repayment strategies and see the impact of making extra payments.

14. What's the role of compound interest in dividend reinvestment?

When you reinvest dividends instead of withdrawing them, you increase the principal on which interest is calculated. This creates a compounding effect, further accelerating your returns, especially in dividend-paying stocks.

15. How can I maximise the benefits of compound interest?

To maximise compound interest, invest regularly, use tax-efficient accounts like ISAs, reinvest your returns, and start investing early. Even small amounts invested over long periods can grow significantly through the power of compounding.


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