Ideal body proportions Calculator WristcmWrist CalculateReset ChestChest HipHip WaistWaist LegLeg NeckNeck ArmArm ShinShin ForearmForearm Formula 6.5 waist girthis a chest girth. Waist girth equals 70% of chest. 53% of the chest equal to hip girth. Neck is equal to 37% of chest girth. Biceps is equal to 36% of chest girth. Lower leg is equal to 34%. Forearm girth is equal to 29% of chest girth.