Err nope. Wait a moment. That's not how Boost Bank computes their daily interest.

https://support.myboostbank.co/hc/en-gb/art...rest-calculated

First, the daily interest has to be rounded to 10 decimal points and then the daily interest accrued is rounded to 2 decimal points only.

So using saving account as example, 10.46 * 0.025/366 = 0.00071448.. when rounded to 2 d.p., you get 0.00 because the 3rd decimal place is still 0...

So we need to rethink our formula and our goal is to earn a daily interest of 0.005, so that when it's rounded up to 2 d.p. you get 0.01 accrued interest per day to be paid out after 7 days later.

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With the above in mind, the new formula is:

Saving account: 0.005*366/0.025 = 73.20 MYR

Normal saving jar: 0.005*366/0.036 = 50.84 MYR (up to 8 jars)

Special saving jar: 0.005*366/0.04 = 45.75 MYR

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Effective interest rate is:

Saving account: 0.01*366/73.20 = 5% p.a. 

Normal saving jar: 0.01*366/50.84 = 7.2% p.a. (up to 8 jars)

Special saving jar: 0.01*366/45.75 = 8% p.a. !

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So it's the same as GX Bank, only thing is the interests are paid out every 7 days instead of every day. You will lose 6 days of interests of interests, assuming reinvestment rate of 3.8% p.a. (aka Rize), no special saving jar, to first order (we ignore "interests on interests on interests"), we lose 0.09*6*52*0.038*6/366 = 0.017 MYR every week for a total of 0.884 MYR per year. It seems that after all, the 6-day withholding period does not incur a significant opportunity cost over GX Bank's daily interest, to first order.  

Hey, looks like Boost Bank is as good as GX Bank after all!