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Savings Interest Calculator

Compare simple gross interest with a compounded balance using an annual equivalent rate.

Last reviewed

Savings Interest Calculator

Compounded gross interest

£400.00

Simple interest comparison£400.00
Closing compounded balance£10,400.00

Reading the result

The same numeric annual rate is used for both comparisons; no contributions or withdrawals are made.

How it works

Simple interest multiplies the deposit by the annual rate and fraction of a year. The compounded comparison raises one plus AER to the years held.

Worked examples

Worked example

Deposit (£): 10000; Annual rate / AER (%): 4; Months: 12

  1. Simple interest multiplies the deposit by the annual rate and fraction of a year. The compounded comparison raises one plus AER to the years held.
  2. Simple interest comparison: £400.00
  3. Closing compounded balance: £10,400.00

Compounded gross interest: £400.00

Assumptions

The result depends on the following. If any of them do not match your situation, treat the figure as indicative only.

  • The same numeric annual rate is used for both comparisons; no contributions or withdrawals are made.

What this calculator does not do

  • Interest is gross before tax. Variable rates, tiered balances, bonus periods and ISA eligibility are not modelled.

Methodology

Simple interest multiplies the deposit by the annual rate and fraction of a year. The compounded comparison raises one plus AER to the years held.

Inputs are processed locally. Displayed amounts are rounded; the calculation retains precision.

Frequently asked questions

Does this deduct savings tax?

No. Savings tax depends on your income, allowances and account type. The results show gross interest.

Can I use it for less than a year?

Yes. Enter the number of months. Actual bank interest may use daily balances and a specific day-count convention.

Please note: Results are estimates for general information only and are not financial, tax or legal advice. Figures depend on the assumptions listed on each page and on your personal circumstances.