Well, you are multiplying a ratio and a ratio, not the actual number of kills against the number of deaths. The ratio for player 1 is 2.0 and player 2's is 0.50. If you add these then divide by 2, you're not actually comparing total deaths against total kills. Player 1 - 10 kills / 5 deaths Player 2 - 5 kills / 10 deaths That equals - 15 total kills in the game and 15 total deaths. 15/15= 1, which is the average of kills to deaths, not the average k/d ratio. A ratio of the kills is different from a fraction of the kills, in that a fraction is a part of a whole and can't have a 0 as a numerator or denominator, where a ratio can. Also, you are comparing each individual players number of kills against their number of deaths in a ratio. You're not comparing the total kills to the total deaths in a ratio. If you took - Player 1 - 10/15= 0.666666 Player 2 - 5/15= 0.333333 Total - 0.999999 or 1.0 This is each players' percentage of kills compared to the total number of deaths. But, to get the average kdr, you're comparing each players ratio of individual kills to their individual deaths. So, in this example game, the average of total kills to total deaths is 1.0. While, the average k/d ratio is 1.25.