Interest Calculator
Calculate simple and compound interest on your savings
Last updated: August 2026
Savings Details
Savings Breakdown
Calculation Details
Simple vs Compound Interest
Simple interest is calculated only on the principal amount, while compound interest is calculated on the principal plus accumulated interest. UK banks typically quote the AER (Annual Equivalent Rate) which shows the true annual return with compounding.
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Reviewed by
Alexandre Bernier, LLM (UK), CFP®, CIM®, PFP®. Financial planner with 18 years in banking and wealth management, holding a UK master of laws and the Canadian CFP®, CIM® and PFP® designations. Writes and reviews every calculator and article on FinanceToolz.
Last updated: August 2026. How figures are sourced, reviewed and corrected is set out in our editorial policy. This is general information, not regulated financial advice.
Sources
Every rate and threshold used by this calculator is taken from the official pages below. If a figure here disagrees with one of these, the official page is right, please tell us.