MoneySavingExpert Chair, Martin Lewis · Editor, Marcus Herbert

# Calculating Interest

3 replies 737 views
Forumite
1.2K Posts
sorry for the silly question

if a normal cash isa is offering 3% for the year

how much interest would I gain if:

a) I deposited the full £5340 at the beginning of the current tax year

and

b) in monthly increments of £445, totaling £5340 at the end of the year.

## Replies

• Forumite
21.1K Posts
Forumite
About £240. £160 on the lump sum and £80 on the monthly payments.
:footie:
Regular savers earn 6% interest (HSBC, First Direct, M&S) Loans cost 2.9% per year (Nationwide) = FREE money.
• Forumite
2.2K Posts
Forumite
You can do (a) using a calculator and you can do (b) quite simply using Excel.

(a) = £160.20
(b) = ~£88 (exact number depends on which days of the month you deposit the monthly payments)
• Forumite
31.5K Posts
Forumite
a) £5,340 x 0.03 = £160.20

b) £445 x 12 x 0.03 / 12 x 6.5 = £86.77

'b' assumes you make the first instalment on 6th April and the last one on 6th March
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