In Hong Kong it is spelled as To and in Macao as Tou, based on the pronunciation of 杜 in Cantonese.

In Singapore and Malaysia, it is spelled as Toh, based on the pronunciation of 杜 in Hokkien.

However, when diacritics are dropped, it can also be from the Vietnamese surnames Dư 余 or Dũ 俞 (for both, the Chinese equivalent is Yu).

The Fan (范) and Du clans share a common ancestor.

It was found to be the 330th most common surname, shared by 140,060 people or 0.011% of the population, with the province with the most being Shandong.