Financial Calculator Online

Calculate simple and compound interest on a lump sum. Ideal for quick savings and loan interest estimates.

Initial savings or loan amount.

Simple vs compound interest

Simple interest is calculated only on the original principal. Compound interest is calculated on the principal plus any interest already earned, so it grows faster over time.

This calculator assumes annual compounding for the compound interest figure. Real savings accounts and loans may compound monthly or daily, which will give slightly different results.

Example

If you invest £10,000 at 5% per year for 5 years:

  • simple interest = £10,000 × 0.05 × 5 = £2,500
  • compound interest ≈ £2,762.82
  • final amount ≈ £12,762.82

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