Cognomen Yukai (Yukai 
, 钰凯 , ユカイ ) , in all the world, is quite a rare family name. The cognomen Yukai is habitual in Taiwan, where it is a rare surname, Singapore, and Japan. Not in comparison with a country's population, it most frequently occurs in Eastern Asia, particularly Japan, China, and Taiwan. More prevalently, Yukai is the forename as well as the last name.
| VARIANT | COUNTRY |
|---|---|
| Yukai | Japan, China, United States, Singapore, Taiwan |
| 钰凯 | China |
| ユカイ | Japan |
| Юкаи | Russia, Kyrgyzstan |
Йукаи, 与凯, 予凯, 予开, 予恺, 予蒈, 予锴, 于凯, 于开, 于恺, 于铠, 于锴, 余凯, 余开, 余锴, 喻凯, 域凯, 妤凯, 妤开, 妤锴, 宇凯, 宇剀, 宇开, 宇恺, 宇慨, 宇铠, 宇锴, 寓凯, 寓恺, 庾开, 彧恺, 彧锴, 御凯, 愈凯, 愈开, 愉凯, 愉恺, 昱凯, 昱开, 昱恺, 昱锴, 榆凯, 榆开, 榆铠, 欲凯, 毓凯, 毓垲, 毓开, 毓恺, 毓慨, 毓锴, 浴凯, 浴开, 淯凯, 淯铠, 渝凯, 渝剀, 渝恺, 煜凯, 煜凱, 煜垲, 煜开, 煜恺, 煜铠, 煜锴, 燏凯, 玉凯, 玉凱, 玉开, 玉恺, 玉揩, 玉铠, 玉锴, 玙凯, 瑜凯, 瑜锴, 禹凯, 禹开, 禹恺, 禹锴, 禺凯, 羽凯, 羽凱, 羽开, 羽恺, 羽锴, 聿凯, 聿恺, 育凯, 育开, 育恺, 育愷, 育揩, 育铠, 育锴, 芋凯, 虞凯, 虞锴, 裕凯, 裕垲, 裕开, 裕恺, 裕锴, 誉凯, 誉垲, 誉开, 誉恺, 誉锴, 豫凯, 豫恺, 豫锴, 逾恺, 遇凯, 遇开, 郁凯, 郁开, 郁恺, 郁锴, 钰垲, 钰开, 钰恺, 钰铠, 钰锴, 雨凯, 雨开, 雨恺, 雨铠, 雨锴, 预凯, 驭凯, and 驭铠