Typically, ldl (low density lipoproteins) greater than is considered high cholesterol.

Typically, LDL (low density lipoproteins) greater than 160 md/dL (4.1 mmol/L) is considered high cholesterol.
LDL is considered as the bad cholesterol because of its increased risk of creating plaque buildup. It is used in measuring the risk of heart disease. 
160 – 189 mg/dL (4.1 – 4.9 mmol/L) is considered as high cholesterol. Greater than 189 is considered as very high.