Every case looks exciting on the reel. The numbers behind it are less exciting, and knowing them is the best way to avoid nasty surprises. This guide covers the official Valve odds, how third-party case sites differ, and a simple way to judge whether a case is worth its price.
Valve’s official drop rates
Valve published the drop rates for its own weapon cases in 2017, and they have stayed the reference point ever since. Every official case uses the same split by rarity:
| Rarity | Colour | Chance per case |
|---|---|---|
| Mil-Spec | Blue | 79.92% |
| Restricted | Purple | 15.98% |
| Classified | Pink | 3.20% |
| Covert | Red | 0.64% |
| Rare special item (knife or gloves) | Gold | 0.26% |
A gold drop happens roughly once every 385 cases on average. “On average” matters: you could hit one in your first ten cases or go a thousand without one. Each opening is independent, so a long dry streak does not make the next case more likely to pay out.
On eligible items there is also a separate 10% chance that the skin is StatTrak™, and every skin rolls a random float (wear) value, which can change its price a lot.
How case sites are different
Third-party case opening sites don’t use Valve’s cases. They build their own, fill them with skins they choose, and set their own chance for each item. That has a few consequences:
- Odds are per case, not per rarity. A site’s case might give a 1% chance at one specific knife and a 60% chance at a cheap skin. Good sites show the exact chance next to every item.
- The site sets the price. A case costs whatever the site decides, and item values are based on the site’s own price list, which may not match the Steam Market or other marketplaces.
- There is always a house edge. Across all its cases, the site pays back less than it takes in. That margin is how it makes money.
None of this is hidden on a reputable site, but you do have to look for it.
Working out what a case is worth
The number that matters is the expected value (EV): the average value you get back per opening. You calculate it by multiplying each item’s value by its chance and adding everything up.
A simplified example with a case that costs $5:
| Item | Value | Chance | Value × chance |
|---|---|---|---|
| Cheap skin | $1.00 | 70% | $0.70 |
| Mid skin | $6.00 | 25% | $1.50 |
| Good skin | $30.00 | 4.5% | $1.35 |
| Knife | $300.00 | 0.5% | $1.50 |
| Total | 100% | $5.05 |
Here the EV is $5.05, just above the $5 price, which would be unusually generous. Most real cases come out below their price. If a case costs $5 and its EV is $4.50, you lose about 10% on average per opening, and the more you open, the closer your results drift toward that average.
A few quick checks before you open anything:
- Do the chances add up to 100%? If a site doesn’t show every item’s chance, treat that as a red flag.
- How much of the EV comes from the rare item? In the example above, the knife supplies almost a third of the value while dropping only once in 200 openings. Most of the time you get the cheap skin.
- Are the item values realistic? Compare the listed value of a few items with a marketplace you trust.
Provably fair is not the same as good odds
Many sites advertise “provably fair”. That lets you check that a result wasn’t changed after you opened the case, and it’s worth having. It does not tell you whether the odds or the prices are fair. A case can be fully provably fair and still have a poor expected value. We explain how the system works in our provably fair guide.
The bottom line
Case opening is entertainment with a built-in cost. Treat the money you put in as spent, look at the chances before you open, and prefer sites that show odds for every item. If you want to try a site without spending much, check our bonus codes for free cases and balance. And if it ever stops being fun, take a look at our responsible gambling page.
