Compound interest calculator that will figure out how much a certain amount of money will be worth over a certain period of time. How much would $25,000 be worth if it was compounded monthly at an annual rate of 4% after 15 years? How much would $5,000 be worth if it was compounded monthly at an annual rate of 3% after 35 years? Tools. If interest is compounded yearly, then n = 1; if semi-annually, then n = 2; quarterly, then n = 4; monthly, then n = 12; weekly, then n = 52; daily, then n = 365; and so forth, regardless of the number of years involved.