For those familiar with typeface design, there is no doubt that the Latin and Latin-like glyphs—to include those for Greek and Cyrillic—in Source Han Sans are based on Source Sans Pro. One may also wonder about the half-width Latin glyphs in Source Han Sans and how they compare to those in Source Code Pro. The purpose of this short article is to make these relationships and differences clear, or at least clearer.

The example at the top of this article illustrates only two weights: Normal and Bold for Source Han Sans (on the left), and Regular and Bold for Source Sans Pro and Source Code Pro (on the right). The first and third lines compare Source Han Sans (on the left) and Source Sans Pro (on the right), and the second and fourth lines compare the half-width Latin glyphs in Source Han Sans (on the left) and Source Code Pro (on the right).

There are two primary differences between the glyphs that are common in Source Han Sans and Source Sans Pro:

The interpolation ratios between the masters are different. Source Han Sans is available in seven weights: ExtraLight, Light, Normal, Regular, Medium, Bold, and Heavy. Source Sans Pro is available in six: ExtraLight, Light, Regular, Semibold, Bold, and Black. While some of the weight names are the same, one should not expect that the interpolation ratios are the same. They will be close, relatively speaking—and perhaps close enough for government work—but not precisely the same.The Latin, Latin-like, Greek, and Cyrillic glyphs in Source Han Sans are based on Source Sans Pro, but have been adapted for use in Source Han Sans, which mainly involved scaling. In the case of the Normal and Bold weights, the Source Sans Pro glyphs were scaled to 113% and 115%, respectively. That is why the Source Han Sans glyphs appear to be slightly larger than those in Source Sans Pro. Why was this done? The short answer is to prevent the tail wagging the dog. The long answer is that the Latin and Latin-like glyphs in a CJK font represent a minority, and when it comes to harmonizing glyphs, the minority are modified to better harmonize with the majority, and not vice versa.

The half-width Latin glyphs in Source Han Sans, which are exposed via the 'hwid' GSUB feature, are different from the glyphs in Source Code Pro in the following ways:

Like Source Sans Pro, the interpolation ratios are different for all weights.The half-width Latin glyphs in Source Han Sans are simply that: half-width, meaning 500-unit glyph widths. The glyphs in Source Code Pro are monospaced, using 600-unit glyph widths, meaning that they are not half-width.The glyphs themselves are also different, particularly the one for zero (0) whose glyph in Source Han Sans lacks a center dot to more easily distinguish it from uppercase O (which is important when working with source code).

Many thanks for the continued interest in Source Han Sans!