How CS2 case odds work
Every CS2 case follows the same five-tier drop structure set by Valve. When you open a case the game rolls into a tier first, then picks a skin from that tier uniformly. The official tier probabilities are:
- Mil-Spec (blue) — 79.92%
- Restricted (purple) — 15.98%
- Classified (pink) — 3.20%
- Covert (red) — 0.64%
- Rare Special (knife or glove, gold) — 0.26%
On top of that, every drop has a 10% chance to roll as StatTrak (where applicable) and a randomly rolled float that determines the wear. Those secondary rolls affect the resale value but not the tier probability itself.
How to read expected value
Expected value (EV) is the average payout you would receive per open if you opened the case an infinite number of times. It is calculated by summing each tier's probability multiplied by the average sale price of skins in that tier. Subtract the cost of a case + key and you get net EV: the average amount you gain or lose per open.
In almost every CS2 case, the net EV is significantly negative. The rare special tier (the gold knives and gloves) carries most of the value, but its 0.26% chance means you would need to open hundreds of cases to realise it. That's why most case-opening is, mathematically, a losing proposition over the long run.
FAQ
What is the best CS2 case to open?
"Best" depends on goal. If you want the highest expected value, look at older cases where covert skins have appreciated. For pure entertainment, the cheapest cases give you the most opens per dollar. This calculator lets you compare any case quickly.
Do CS2 cases have rigged odds?
No — the tier odds are published and the same for every player. What varies is the value of the skins inside each tier and the wear/StatTrak rolls applied afterwards.
How do I open a case for free?
You can't open Valve cases without a key, but you can win skins, knives and gloves through free CS2 giveaways. If you do want to open cases on third-party sites, check our vetted partner reward sites for codes that improve the value.
Why are my real-world opens worse than the simulator?
Small sample sizes diverge from EV. The simulator demonstrates the same math the game uses, but a run of 10 opens — or even 100 — can sit far from the long-run average. Variance is what makes gambling feel rewarding, and what makes it expensive.