Sizes of cello vary greatly. The standard size of the cello can be referred as "full-size". There are cellos that too, come in small sizes from "7/8" and "3/4" down to "1/16" sized cellos (e.g. 7/8, 3/4, 1/2, 1/4, 1/8, 1/10, 1/16). The cellos that are smaller in size are identical to the standard cellos in range, usage and construction, but it is simply "scaled down" for the advantage of children and shorter adults.

It must be noted here that a "half size" cello is half the volume of the full size, not the half the length (i.e., the 1/8-size cello would be "half-size" in terms of length). For example, a 1/10 size cello that is meant to be used by small children is slightly larger than violin (and as such can be played by an adult player like one), but about twice as thick, and the C string tends to be quite slack due to the difficulty for such a small string to produce a sound that low. There are many smaller cellist who prefer to play "7/8" cello as the hand stretches in the lower positions are less demanding.

Although very rare but cello with sizes that are larger than 4/4 exists! And players with large hands may play a slightly larger than full-sized cello. Cellos that were made approximately before 1700 tended to be considerably larger than those made and commonly played today.