Confused, and I should remember this! Pressure settings.

Hi All,

I'm looking at a trace to see if it busted any airspace. I learned all this for the Bronze exam and for some reason it's all flooding out of my head!

My GPS logger says at one point at 5500' I may have busted altitude, but the logger is assuming standard pressure (1013).

The airspace in question starts at 5500' above mean sea level. The pressure I've found for the day was 1021mb - So, if the GPS logger was reading 5500', what should it read if I had it set to QNH 1021?