Compounding frequency is the whole argument
Indian retail FDs usually compound quarterly (n=4). Annual n=1 looks better on a dishonest banner. Senior-citizen extra is a rate you type, not a checkbox that guesses your age.
Worked example: ₹2 lakh, 7%, 5 years, quarterly
A = 200000 × (1+0.07/4)^(20). Interest is maturity minus principal. The bank’s certificate still wins on day-count.
Questions
Are my numbers uploaded?
No. Arithmetic stays in this tab. Remember writes this browser only.
Can I share the inputs?
The URL hash (#) stores fields. Copy the address bar. Nothing is sent as a query string to a server of ours.
Is this a filing?
No. Print the worksheet. Argue with payroll or a CA. Do not paste this into an ITR as authority.
TDS?
Banks TDS interest above a threshold. Not modelled. Senior rate is whatever you type.