How can I recalibrate the touchscreen on my iPhone?
The iPhone's capacitive touch screen doesn't have the concept of calibration.

To fix the problem you're experiencing, I suggest trying each of the following options:


Hard reset of the phone by holding the Home and Sleep buttons for 10 seconds.
"Reset All Settings" from Settings &rarr; General &rarr; Reset.
"Erase All Content and Settings" from Settings &rarr; General &rarr; Reset.
If your phone is still under warranty or covered by AppleCare, bring it to Apple and they will repair or replace it for you.
If not covered, then there are guides for replacing the front panel (first-gen iPhone), which contains the digitizer.