After each game ends, the Uno online game will calculate the score by adding all the cards in your hand according to the rules:

 

Cards 0-9 will add up according to the number of points on the card

 

Cards drawn 2, reversed, turned ban will add 20 points

 

Cards change color, draw 4 will count 50 points

 

 

Whoever has less points will be the winner, so when you realize you can't win, you should play all the functional cards and big cards first to reduce the score when time runs out.