同身寸者，谓同于人身之尺寸也。人之长短肥瘦各自不同，而穴之横直尺寸亦不能
一，如今以中指同身寸法一概混用，则人瘦而指长，人肥而指短，岂不谬误？故必因其形而
取之，方得其当。如标幽赋曰∶取五穴用一穴而必端，取三经用一经而可正。盖谓并邻经
而正一经，联邻穴而正一穴。譬之切字之法，上用一音，下用一韵，而夹其声于中。则其经
穴之情，自无所遁矣。故头必因于头，腹必因于腹，背必因于背，手足必因于手足，总其长短大小而折中
之，庶得谓之同身寸法。法附前各条之下。而后之所谓中指同身寸法者，虽不可混用，而亦有当用之处，并列于后。
以男左女右手大指中指圆曲交接如环，取中指中节横纹两头尽处，比为一寸。凡手足
尺寸，及背部横寸，无折法之处，乃用此法，其他不必混用。
骨度篇曰∶人长七尺五寸者，其骨节之大小长短各几何？伯高曰∶头之大骨围二尺六寸。盖古之尺
小，大约古之一尺，得今之八寸。其言七尺五寸者，得今之六尺；其言二尺六寸者，得今之二尺零八分也。
其余仿此。然骨大者必有太过，骨小者必有不及。凡用折法者，但随人之大小而为盈缩，庶尽其善。
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同身寸，指的是与人体自身尺寸相一致的度量方法。人的高矮、胖瘦各不相同，因此穴位的横向和纵向尺寸也不能统一。如果现在用“中指同身寸法”一概混用，那么人瘦而手指长，人肥而手指短，这难道不是谬误吗？所以必须根据个人的形体特征来取量，才能恰当准确。正如《标幽赋》所说：“选取五个穴位时，用一个穴位作为基准就必须端正；选取三条经脉时，用一条经脉作为基准就可以校正。”这是指通过邻近的经脉来校正一条经脉，通过邻近的穴位来校正一个穴位。这就好比切字注音的方法，上面用一个音，下面用一个韵，将声音夹在中间进行拼读。这样，经脉和穴位的实际情况，自然就无法隐藏了。因此，头部必须依据头部的尺寸，腹部必须依据腹部的尺寸，背部必须依据背部的尺寸，手足必须依据手足的尺寸，综合其长短大小而折中衡量，这才称得上是同身寸法。本法附在前文各条之下。而后世所谓的“中指同身寸法”，虽然不可混用，但也有应当使用的场合，一并列在后面。
让男性左手或女性右手的拇指和中指弯曲，两指端相接成环状，取中指中间一节横纹两端尽头处之间的距离，定为一寸。凡是手足部位的尺寸，以及背部横向尺寸，在没有其他折量方法的地方，才使用这种方法，其他情况不必混用。
《灵枢·骨度篇》说：“身高七尺五寸的人，其骨节的大小长短各是多少？”伯高回答说：“头部大骨的周长是二尺六寸。”大概古代的尺较小，大约古制的一尺，相当于现在的八寸。文中所说的七尺五寸，相当于现在的六尺；所说的二尺六寸，相当于现在的二尺零八分。其余类推。然而，骨骼大的人必然有超过标准之处，骨骼小的人必然有不足标准之处。凡是用折量法的时候，只要随着人的大小而增减，就能达到尽善尽美。
Tongshen Cun (Same-Body Inch) refers to a measurement method consistent with the individual's own body dimensions. People vary in height and weight, so the horizontal and vertical measurements of acupoints cannot be uniform. If the Zhongzhi Tongshen Cun Method (Middle Finger Same-Body Inch Method) were applied indiscriminately, it would lead to errors: for thin individuals with long fingers, the measurement would be too large; for obese individuals with short fingers, it would be too small. Therefore, one must measure according to the specific physical constitution to ensure accuracy. As stated in *Biao You Fu* (Marking the Profound): "When selecting five acupoints, using one as a reference must be precise; when selecting three meridians, using one as a reference allows for correction." This implies correcting a meridian by its neighboring meridians and an acupoint by its neighboring acupoints. It is akin to the method of phonetic notation in Chinese characters, where an initial sound and a final rhyme are combined to produce the correct pronunciation. In this way, the true nature of meridians and acupoints becomes clear. Thus, head measurements must be taken from the head, abdominal measurements from the abdomen, back measurements from the back, and limb measurements from the limbs, averaging their lengths and sizes to achieve the Tongshen Cun method. This method is detailed in the preceding sections. Although the later "Zhongzhi Tongshen Cun Method" should not be used indiscriminately, there are specific instances where it is appropriate, which are listed below.
For men, use the left hand; for women, use the right hand. Bend the thumb and middle finger so that their tips touch, forming a ring. Measure the distance between the two ends of the transverse crease at the middle phalanx of the middle finger as one cun. This method is used only for measuring the limbs and the horizontal width of the back where other proportional methods are not applicable; it should not be mixed with other contexts.
The *Gu Du Pian* (Chapter on Bone Measurements) states: "For a person seven chi five cun tall, what are the sizes and lengths of their bone joints?" Bo Gao replied: "The circumference of the skull is two chi six cun." Generally, ancient chi were smaller; approximately one ancient chi equals eight modern cun. Therefore, the mentioned seven chi five cun corresponds to six modern chi, and two chi six cun corresponds to two chi eight fen modernly. The rest follows this pattern. However, individuals with larger bones will exceed standard measurements, while those with smaller bones will fall short. When using proportional measurement methods, adjustments should be made based on the individual's size to achieve optimal accuracy.