South Georgia and South Sandwich Islands is about 50 times bigger than Guernsey.

Guernsey is approximately 78 sq km, while South Georgia and South Sandwich Islands is approximately 3,903 sq km, making South Georgia and South Sandwich Islands 4,904% larger than Guernsey.
Tip: This to-scale comparison of Guernsey vs. South Georgia and South Sandwich Islands uses the Mercator projection, which distorts the size of regions near the poles.
Compare further: South Georgia and South Sandwich Islands vs. Guernsey