Day: July 21, 2003

Web link of note: Conny
(At http://www.lemonsupreme.com)

What are the odds of winning a battle in Risk ? (I’m talking about “classic” Risk now, not “Risk 2210“).

I was actually calculating all these out myself, and then I realised- “duh- this is the internet- someone has definitely already done this and posted it online!”

So here’s the info, taken from the Probabilities section from the RISK FAQ.

	Defender rolls 2 dice (2 or more armies)	Defender rolls 1 die (1 army)
Attacker rolls 3 dice (4 or more armies)	Att lose 2: 29.26% Def lose 2: 37.17% Both lose 1: 33.58%	Att lose 1: 34.03% Def lose 1: 65.97%
Attacker rolls 2 dice (3 armies)	Att lose 2: 44.83% Def lose 2: 22.76% Both lose 1: 32.41%	Att lose 1: 42.13% Def lose 1: 57.87%
Attacker rolls 1 die (2 armies)	Att lose 1: 74.54% Def lose 1: 25.46%	Att lose 1: 58.33% Def lose 1: 41.67%

If you’re more of a completist, there is Scott Bartell’s RiskOdds Calculator, which shows you the complete odds for an entire battle, with an option to choose how many armies have to die before the attacker gives up.

See also Scott’s FAQ about the calculator.