Butter contain, about . . . . . . . . Fat.

Butter contains, about 81% Fat.
Butter is a dairy product made from the fat and protein components of churned cream. It is a semi-solid emulsion at room temperature, consisting of approximately 80% butterfat.
Commercial butter is about 80% butterfat and 15% water; traditionally-made butter may have as little as 65% fat with 30% water. Butterfat is a mixture of triglyceride, a triester derived from glycerol and three of any of several fatty acid groups.