What This Calculator Does
The Daily Interest Earned Calculator tells you exactly how much interest a deposit generates each day. It is useful for savings accounts, fixed deposits, money market accounts, and any simple-interest scenario where interest accrues daily. Enter your principal, the quoted annual interest rate, and the number of days you want to project, and the tool returns the per-day interest, the total interest over that period, and your ending balance.
How to Use It
Type in your deposit amount, the annual percentage rate offered by your bank, and how many days you plan to hold the money. The calculator converts the annual rate into a daily rate by dividing by 365, then multiplies by your principal to find the daily interest. Multiplying by the number of days gives the running total.
The Formula Explained
The core equation is $$\text{Daily Interest} = \text{Principal} \times \left(\frac{\text{annual rate}}{365}\right)$$ The annual rate is expressed as a decimal (5% becomes 0.05), and dividing by 365 spreads that yearly rate evenly across each day of the year. This is the standard "actual/365" simple-interest convention; some institutions use a 360-day year, which would produce slightly higher daily figures.
Worked Example
Suppose you deposit $10,000 at an annual rate of 5%. The daily rate is \(0.05 \div 365 = 0.00013699\). Multiply by $10,000 and you earn about $1.37 per day. Over 30 days that is roughly $41.10 in total interest, leaving an ending balance near $10,041.10.
FAQ
Does this use compound interest? No — it applies simple interest, so each day earns the same amount based on the original principal. For compounding, daily interest would be added to the balance before the next day's calculation.
Why divide by 365? Most savings products quote an annual rate and accrue interest daily on a 365-day basis. If your bank uses 360 days, replace 365 in the formula.
Is the rate before or after tax? The calculator uses the gross rate you enter; any interest tax would reduce the net amount you keep.
