Slovenia is about 5 times bigger than South Georgia and South Sandwich Islands.

South Georgia and South Sandwich Islands is approximately 3,903 sq km, while Slovenia is approximately 20,273 sq km, making Slovenia 419% larger than South Georgia and South Sandwich Islands.
Tip: This to-scale comparison of South Georgia and South Sandwich Islands vs. Slovenia uses the Mercator projection, which distorts the size of regions near the poles.
Compare further: Slovenia vs. South Georgia and South Sandwich Islands