For typical private cars, front brake pads last 30,000–50,000 km, rear pads 60,000–80,000 km. Replacement intervals vary based on road conditions, driving habits, and braking style. Mechanics or 4S shops will advise when replacement is needed.
Experienced drivers can also judge based on braking feel: if braking feels soft or stopping distance increases, replace promptly. If metallic scraping occurs (indicating metal-to-metal contact), replace immediately or seek professional help.