Enter your own figures to calculate simple interest with straightforward finance maths and clearly visible assumptions.
Inputs
This topic also has a deeper guide and a printable reference pack, so you can move from the live answer into the method, assumptions, and worked examples without leaving the topic cluster.
These are the main values the calculator uses. Keep the units consistent and, where relevant, match the assumptions explained in the related guide.
Unit: GBP
Enter the value using the unit shown on the field.
Unit: %
Enter the value using the unit shown on the field.
Unit: years
Enter the value using the unit shown on the field.
Use this calculator when you need a simple interest estimate from values you control yourself.
The main result appears first, with supporting figures underneath to make the calculation easier to check and compare.
These calculators apply the mathematics shown on the page only. Fees, taxes, regulation, and commercial terms should be handled separately unless you enter them explicitly.
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