In a recurring deposit you pay a fixed amount every month. Each instalment earns interest, compounded quarterly, for the months it stays - the first instalment for the whole term, the last for just one month.
How it is worked out
Maturity = Σ R × (1 + r / 4)4 × (n − k + 1) / 12 over each instalment k, where R is the instalment, r the yearly rate and n the number of months.
Questions
Why is the 'a year' return below the quoted rate?
Your money goes in gradually, so on average it is invested for about half the term. The figure shown is the equivalent return on the instalments as they were paid.
What if I miss an instalment?
Banks charge a small penalty and the maturity changes; this calculator assumes every instalment is paid on time.