1, the same measurement time (people’s morning and evening heights are different). 2, the same standard height measurement ruler (when measuring at home, you can also measure after putting a piece of paper on the wall, draw a line and then measure the height, but the ruler on the head must be perpendicular to the wall, preferably with a triangular ruler). 3, the same measurer (different people may have differences in the tightness of the calipers when measuring). 4, the same standing method of the person being measured (required to lean on both feet together, heels, hips, back, head are against the wall, and the head against the wall must pay attention to both eyes flat, not too tilted, chest, abdomen, waist as straight as possible.