Q: Which rating is used when calculating the rating adjustment after the game ends?

A: The higher of the two ratings — when the first move was made and when the last move was made — is used when calculating the rating adjustment after the game is over.

For example, if player A plays against player B and their ratings were 1300 for player A and 1400 for player B when the game was started, but just before the game ends their ratings are 1250 (A) and 1450 (B). The following ratings will be used: 1300 for player A (1300>1250) and 1450 for player B (1400<1450), when calculating the rating difference for the Elo formula. The only exception to this rule is if the player hadn't completed the first 5 rated games yet when the game was started, in which case the rating at the end of the game will be used for that player (everyone has a provisional rating of 1200 during their first 5 rated games).

» More about the rating system.