An ISA (Individual Savings Account) Interest Calculator helps you estimate how much your savings will grow over time by factoring in your initial deposit, regular contributions, interest rate, and compounding frequency. Here’s how you can estimate your ISA savings growth: For more information please visit Calculate ISA Interest

1. Key Factors Affecting Your ISA Growth

  • Initial Deposit – The amount you start with.
  • Regular Contributions – Monthly or yearly savings added to the ISA.
  • Interest Rate – The annual interest rate (fixed or variable).
  • Compounding Frequency – How often interest is added to your balance (daily, monthly, annually).
  • Time Period – The number of years you plan to save.

2. ISA Interest Calculation Formula

For compound interest, the formula used is: A=P×(1+rn)n×t+(C×(1+rn)n×t−1rn)A = P \times (1 + \frac{r}{n})^{n \times t} + \left( C \times \frac{(1 + \frac{r}{n})^{n \times t} – 1}{\frac{r}{n}} \right)A=P×(1+nr​)n×t+(C×nr​(1+nr​)n×t−1​)

Where:

  • A = Final amount after interest
  • P = Initial deposit
  • r = Annual interest rate (decimal form, e.g., 2% = 0.02)
  • n = Number of times interest is compounded per year
  • t = Number of years
  • C = Regular contributions

3. Using an ISA Interest Calculator

Most online ISA calculators require you to enter: ✅ Your initial deposit
✅ Monthly contributions (if any)
✅ Interest rate
✅ Compounding frequency
✅ Investment duration

The tool will then estimate your total savings and interest earned.

4. Example Calculation

Scenario:

  • Initial deposit: £5,000
  • Monthly contribution: £200
  • Interest rate: 3% annually
  • Compounded monthly
  • Duration: 10 years

Using the formula or an online calculator, you’d see how much your savings grow, with interest compounding over time.

5. Maximizing Your ISA Growth

✔ Use tax-free allowances – Maximize the £20,000 ISA limit (UK 2024/25).
✔ Choose a high-interest ISA – Compare fixed-rate and variable-rate ISAs.
✔ Opt for frequent compounding – More frequent compounding means more interest earned.
✔ Regularly increase contributions – Even small increases can significantly boost long-term savings.

Would you like a custom calculation for your specific savings plan? 😊