On your iPhone/iPad:
- Settings > General > About > Serial Number
- Enter the Serial Number: selfsolve.apple.com/agreementWarrantyDynamic.do
References:
- support.apple.com/en-us/ht4061 Find the serial number for your iPhone, iPad, and iPod touch
PS. This works for Macs too.
- You’ll find the serial number here: Apple > About this Mac
or
- You can look up your Mac’s support status directly: Apple > About this Mac > Service > Check my service and support coverage status