Unlike pads and rotors, calipers are not a routine wear item - they are built to last a long time. But they do not last forever. Here is how long brake calipers typically last.
Often 100,000 miles or more
A brake caliper can easily last well over 100,000 miles - far longer than pads or rotors; see do calipers wear out. Many cars go their whole life on the original calipers. They are long-life parts, not lifetime-guaranteed ones.
What shortens caliper life
Rust is the big enemy - salt-belt and coastal cars seize guide pins and pistons far sooner; see high-mileage calipers. Old brake fluid that absorbs moisture also corrodes the caliper bore from the inside, which is why fluid flushes protect calipers.
How they finally fail
When a caliper does go, it usually sticks (dragging and overheating one wheel) or leaks past a torn seal; see sticking caliper and brake heat. Both call for replacement.
Make them last
Keep the fluid fresh, service the slides at each brake job, and address rust early; see caliper slide pins. When one finally fails, a loaded replacement plus fresh pads and hardware restores it.