How to Calculate Savings Interest
Quick Answer
- Simple interest: I = P × r × t
- Compound interest: A = P × (1 + r/n)^(n × t)
Where: P = principal, r = annual rate (decimal), t = time in years, n = compounding periods per year.
Example: 10,000 at 4.5% per year, compounded monthly for 2 years.
A = 10,000 × (1 + 0.045/12)^(12 × 2) = 10,000 × (1.00375)^24 = 10,939.30. Interest earned = 939.30.
Savings account interest is the foundation of personal finance. Use the Retirement Calculator on CalConvs to model long-term compound growth.
How Rate Differences Compound Over Time
10,000 saved for 10 years at different rates (monthly compounding):
| Annual Rate | Final Amount | Interest Earned |
|---|---|---|
| 1.0% | 11,052 | 1,052 |
| 4.5% | 15,665 | 5,665 |
| 7.0% | 20,097 | 10,097 |
| 12.0% | 33,004 | 23,004 |
Always compare savings accounts using the AER (Annual Equivalent Rate) or APY (Annual Percentage Yield) for a fair comparison.
Savings Interest Rates by Country (2024 Approximate)
| Country and Account Type | Rate Range |
|---|---|
| UK Cash ISA | 4.5 to 5.5% |
| UK Easy access savings | 4.0 to 5.0% |
| US High-yield savings | 4.5 to 5.2% |
| US Standard savings | 0.5 to 1.0% |
| India Bank FD (1 year) | 6.5 to 7.5% |
| India PPF | 7.1% (government guaranteed, annual compounding) |
| Pakistan NSS Defence Savings | 12 to 13% |
| Pakistan Special Savings Certificates | 11 to 12% |
| Australia High-interest savings | 4.5 to 5.5% |
UK Savings: ISA and Non-ISA Accounts
- Cash ISA: Interest is completely tax-free. 2024/25 ISA allowance: £20,000 per year.
- Easy access savings: Interest taxable above the Personal Savings Allowance (£1,000 for basic rate taxpayers). Funds accessible immediately.
- Fixed-rate bond (UK): Higher rates in exchange for locking money away for 1 to 5 years.
- Premium Bonds (UK): No interest. Monthly prize draws with a tax-free prize fund equivalent to approximately 4.4% (2024). Maximum holding £50,000.
India Savings: FD, PPF and Savings Accounts
- Fixed Deposit (FD): Most popular savings vehicle. Locked for a term. Rates: 6.5 to 7.5% for 1-year FDs at major banks.
- Public Provident Fund (PPF): Government-backed. Rate: 7.1%. 15-year lock-in. Tax-free interest and maturity.
- Recurring Deposit (RD): Deposit a fixed monthly amount. Compound interest applied. Suitable for building savings from salary.
Frequently Asked Questions
How do I calculate monthly interest on a savings account?
Monthly interest = (Principal × Annual rate ÷ 12). For example, 50,000 at 6% annual rate: Monthly interest = 50,000 × 0.06 ÷ 12 = 250. At compound interest, this 250 is added to the balance each month.
What is the difference between AER and gross rate?
The gross rate is the advertised annual rate before tax. AER (Annual Equivalent Rate) shows what you would earn if interest were compounded annually, making different compounding frequencies comparable. Always compare savings accounts using AER.
Is a fixed deposit better than a savings account?
Fixed deposits generally offer higher rates than instant-access savings accounts in exchange for locking your money away. If you will not need the money within the term, a fixed deposit typically earns more.
Related Tools
- Retirement Calculator: model long-term compound savings growth
- Inflation Calculator: check whether your savings rate beats inflation
- All Finance Tools: browse all finance tools on CalConvs