MariBank (formerly Seabank) Interest Calculator with Compounding Interest

Use this calculator when you want a multi-day projection: daily interest is added back to the balance (after 20% withholding tax) and the next day uses the new principal. For a single day with no compounding, use the daily interest calculator.

How this projection compounds

Each day, net interest is added to the balance, and the next day uses that new principal. Net interest is the same one-day formula as the daily calculator: balance times the annual rate, divided by 365, then multiplied by 0.80 to remove 20% withholding tax. The difference is that this page repeats that step for the number of days you enter, carrying the new balance forward. For a single day with no compounding, use the daily interest calculator.

Example rate tiers

The rate field is editable. When the balance changes, the calculator fills an example rate: 5% a year at or under ₱250,000, and 3% a year above ₱250,000. Those two tiers are examples built into this tool so you can see compounding without looking up a rate first. They are not a live quote from MariBank. Replace the number with the rate published on MariBank’s fees and rates page if you want the projection to follow the bank’s current offer.

Worked example

Start with ₱100,000. That balance is at or under ₱250,000, so the example rate is 5%. Day 1 gross interest is ₱100,000 × 0.05 ÷ 365, about ₱13.70. After 20% tax, about ₱10.96 is added, and the balance becomes about ₱100,010.96. Day 2 runs the same formula on ₱100,010.96, not on the original ₱100,000, so the credit is slightly larger. Each later day uses the balance from the day before. The table on this page lists that running balance and that day’s net interest.

A balance above ₱250,000 switches the example rate to 3% before you click Calculate. If you type a different rate, the schedule uses the rate in the field, including across the ₱250,000 line. The tier only fills the field. It does not change the rate again in the middle of the day-by-day loop.

What the schedule leaves out

• Deposits or withdrawals during the period. The starting balance only changes by net interest.
• Promo caps, a rate that changes on a calendar date, or a tier the bank applies differently from this example.
• A statement from MariBank. This calculator is independent and is not affiliated with the bank.

Use the result to see how daily compounding behaves after tax. Confirm the credited amount in the MariBank app before you treat it as money you have earned.

Privacy

The MariBank compound interest calculator runs in your browser. Inputs stay on this device unless a page notes an exception. Privacy Policy.