There are three main sizes of wood carving tools; palm size, mid size and full size. Palm sized wood carving tools are used for smaller carvings – especially those carvings that you hold in one hand and the palm tool in the other. Mid size and full size tools are used for medium to larger size carvings. They made to be pushed using one or both hands or may be struck with a mallet.
Wood carving tools are numbered by the size and curvature of the blade. The curvature of the blade or the "sweep" is defined by numbers from #1 to #11. For instance, #1 sweep is a straight chisel and #11 is almost a semi-circle gouge. The other number is the size or the length of the blade and it is mostly stated in millimeters, although some US manufacturers still state the length in inches. For instance, a #4 8 mm gouge has a #4 curvature and it is 8 mm wide at the blade. You may find that the level of curvature may vary between various manufacturers of wood carving tools. When it comes to non basic shapes of tool like v-chisels, spoon bents or back bents the sizes vary too great between different brands.