See what starting later actually costs you, in money — not just "you should start early" advice.
Future value of a monthly investment = PMT × [(1+r)ⁿ − 1] / r, where r is the monthly return and n is the number of months invested. Starting later means fewer months of compounding, even if you invest the exact same monthly amount for the rest of the time.
This is a pure compound-interest calculation from the numbers you enter — no market data, currency, or country assumptions are built in. Real returns vary year to year; this uses one constant average rate for simplicity. Not financial advice.