Calculator tool for Daily Interest

Anyone got a good link for such a tool? I am trying to work out the daily interest rate paid on my Trading212 Cash ISA. The app tells me it is 5.1% AER but I had an email before saying it was dropping to 5% on Sept 9th. I tried one tool but using 5 or 5.1% did not match what Trading212 are paying out:

Daily Compound Interest Calculator (thecalculatorsite.com)

Example:

My ISA balance is £32754.87 and Trading212 are paying £4.47 per day (well it was £4.46 until today). Yet if I use this calculator I get:

5% = £4.49
5.1% = £4.58

So neither match. No doubt I am doing something wrong but I would like to understand what.


Comments

  • eskbanker
    eskbanker Posts: 36,928 Forumite
    Part of the Furniture 10,000 Posts Name Dropper Photogenic
    If the AER is 5.1% and the account pays interest daily, then the gross rate used will be significantly less than 5.1%, to allow for compounding, I make it 4.97% but don't know if they publish a gross rate and also don't know how they deal with rounding....

    https://www.moneysavingexpert.com/banking/interest-rates/#save
  • Ayr_Rage
    Ayr_Rage Posts: 2,511 Forumite
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    @eskbanker is correct, the underlying rate is 4.97% and the AER 5.1% when interest is compounded.

    See the details from the link below, click View Further Details

    https://moneyfactscompare.co.uk/isa/easy-access-cash-isas/

  • AlwaysLearnin
    AlwaysLearnin Posts: 900 Forumite
    Part of the Furniture 500 Posts Name Dropper Mortgage-free Glee!
    edited 11 October 2024 at 4:29PM
    I've only had a T212 cash ISA a few weeks, but this excel formula seems to be working so far to give me an accumulated balance:

    =ROUNDDOWN( [A] * (1+ ((1+ [B] )^(1/365.25)-1) ) ^ (TODAY() - DATEVALUE("[C]")),2)

    [A] = ACCT BALANCE: UPDATE WHENEVER RATE CHANGES
    [B] = AER: CURRENTLY 5.1%
    [C] = DATE LAST UPDATED ‘BALANCE’ AMOUNT: UPDATE WHENEVER RATE CHANGES

    I think in your case it could be (to start from today):

    =ROUNDDOWN(32754.87 * (1+((1+5.1%)^(1/365.25)-1)) ^ (TODAY()-DATEVALUE("11/10/2024")),2)

    or at least that gives you something to work from...
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