The amount of compression in compression socks is measured in mmHg, a measurement that expresses pressure. For mild cases of varicose veins and swelling, compression from 10 to 20 mmHg should be adequate. A compression of 20-30 mmHg is considered strong. For higher compression, you’ll need to get a prescription from your doctor. Remember, your socks should feel tight, but not painful. If you experience serious discomfort or pain, look for socks with a lower compression rating.