The EMI formula, in plain words
An amortized loan charges interest only on what you still owe. Each fixed monthly payment first covers that month's interest, and whatever is left chips away at the balance — so early payments are interest-heavy and late payments are principal-heavy. The payment that makes the balance hit exactly zero on the last month is:
EMI = P × i × (1 + i)ⁿ ÷ [(1 + i)ⁿ − 1]
where P is the amount borrowed, i is the monthly rate (annual rate ÷ 12 ÷ 100) and n is the number of monthly payments. Borrow 25,000 at 9.5% for 5 years: i = 0.0079167, n = 60, EMI ≈ 525.05 — about 31,503 in total, of which roughly 6,503 is interest.
Flat rate vs reducing balance — the trap to know
Some lenders advertise a "flat rate", charging interest on the original amount for the whole term. A 6% flat rate on a 5-year loan costs almost the same as an ~10.9% reducing-balance rate — nearly double what it sounds like. This calculator uses the honest reducing-balance method that banks use for real EMIs; if you were quoted a flat rate, roughly double it before comparing.
Why a small extra payment saves so much
Every extra unit you pay goes 100% to principal, and interest stops accruing on it for every remaining month. On the 25,000 / 9.5% / 5-year example, an extra 50 a month clears the loan 6 months early and saves about 740 in interest — a guaranteed, tax-free return equal to your loan rate. Type any amount into the extra-payment box to see your own numbers; the green card shows the new payoff time, interest saved and months cut.
Reading the amortization schedule
The schedule splits every payment into its interest and principal parts and tracks the falling balance. Watch the crossover point — the month principal starts exceeding interest. On short personal loans that happens quickly; on 20–30-year home loans it can take a decade, which is why prepaying early in a long loan saves far more than the same prepayment made late.
What the calculator assumes
Payments are monthly, in arrears (first payment one month after disbursal), with a constant rate — the standard for personal, auto and fixed-rate home loans. Floating-rate loans re-compute the EMI or the term when the benchmark rate moves, so treat results as a snapshot at today's rate. Processing fees, insurance and late charges aren't included; when comparing lenders, compare the APR (which folds fees in), not just the headline rate.