CS2 Case Opening Sites: Odds, Expected Value and What to Check

Case opening sites sell the same thrill as a Valve case: pay a fixed price, get one random item. The difference is that the site decides what goes in the case, how each item is valued and how likely each one is. This guide shows how to read those numbers, how to calculate what a case is worth before you open it, and what to check about withdrawals.

How case opening works

There are two kinds of case opening, and they work differently.

• Valve cases in CS2. You need the case and a key. The item you unbox goes straight into your Steam inventory, and you can sell it on the Steam Community Market, where Valve takes a 5% transaction fee and a 10% Counter-Strike 2 fee. Our Steam Market fees guide shows what that does to your sale price.
• Third-party case sites. You deposit skins, card money or crypto, and the site gives you a balance. Each case has a price in that balance and a list of items with a percentage next to each. What you win is credited to your site inventory. You can then open more cases, exchange the item, or withdraw it as a skin, which is where most of the friction lives.

Third-party cases can be built around anything: one weapon, one price range, a knife pool. The site sets the price, the item list, the item values and the odds. That is why the maths below matters more on a site than on Steam.

Odds disclosure

The standard public reference for Valve case odds is a 2017 disclosure by Perfect World, the game's publisher in China, made to comply with Chinese loot box rules. It gives the chance of each rarity tier per weapon case:

The same disclosure said any item has a 10% chance of being the StatTrak version. A gold item comes out of roughly 1 in 385 Valve cases (1 ÷ 0.0026).

Third-party sites usually show a percentage next to every item in a case. Read the list before you open:

• Check that the percentages add up to 100%. If they do not, the page is not telling you the full odds.
• Look at how much of the probability sits on items worth less than the case. That is the share of openings that lose money.
• Note the price of each item and compare it with what the same skin sells for on an independent market.

Expected value and house edge

Expected value (EV) is the average return of one opening if you could open the case forever. The formula is the same for every case:

EV = sum of (chance of item × value of item)

Here is a made-up $10.00 case with four outcomes, to show the working:

The contributions add up to $8.30. The case costs $10.00, so you lose $1.70 per opening on average. The house edge is $1.70 ÷ $10.00 = 17%, and the return to player is 83%.

Three things the table makes clear:

• Most openings lose. 70% of the time you get the $1.50 item. Only 30% of openings return the case price or more, and a quarter of all openings only give you your $10.00 back.
• The rare item carries the case. The 0.5% item supplies $2.50 of the $8.30. Without it, the case would return 58%.
• The item values are the site's numbers. If the $50.00 item only sells for $40.00 on a marketplace, the real EV drops and the real edge rises. Recalculate with prices you could actually sell at.

Case battles use the same items and odds, so the per-case edge does not change. You are just sharing the outcome with other players. Upgraders and exchanges add their own margins, so check the payout percentage on those screens too.

Provably fair

Most case sites call themselves provably fair. The site shows you a hash of a secret server seed before you open, your own client seed and a counter (the nonce) go into the roll, and after you rotate seeds you can check that the revealed seed matches the hash and recalculate each result.

That proves the roll was not changed after you clicked. It does not prove the odds table is generous or that the items are fairly priced. Our provably fair guide walks through a verification step by step.

Withdrawal friction

Winning an item on a site and getting it into your Steam inventory are two separate steps. Common sources of friction:

• Wagering before withdrawal. Some sites make you wager your deposit or bonus a set number of times before you can withdraw. Bonus terms often carry a rollover. Read it before you accept any code.
• Item availability. Many sites withdraw through peer-to-peer trades or a marketplace. If nobody is listing the skin you want at the site's price, you wait or pick something else.
• Minimums and verification. Expect a minimum withdrawal, a Steam level or account age requirement, and identity checks before larger withdrawals.
• Exchange spreads. Converting a won item back to balance, or balance to a skin, can cost more than the headline fee. Compare the price the site gives you with a marketplace price.

Steam trade protection

Since July 2025, every CS2 item received in a trade is Trade Protected for 7 days. You can equip it, but it cannot be consumed, modified or transferred during that time, and the trade can be reversed from Steam's trade history. Reversing returns the items to their previous owners and puts a 30-day trade and Market cooldown on the account that reversed.

For case sites this cuts both ways:

• A skin you deposit could be reversed by you for 7 days, so a site may hold skin deposits or limit what you can do with them until the protection ends. Check its deposit rules.
• A skin you withdraw through a peer-to-peer trade could, in theory, be reversed by the sender. Check the site's rules on who carries that risk before you withdraw anything valuable.

Case sites we partner with

These are the partner sites that list case opening as a product. Offers are what our link or code was reported to give on the date shown. Several of these operators publish no gambling license, and all of them block some countries, so read the terms and the restricted-country list on each site first.

Free cases on these sites are their own topic, with their own catches. Our free cases guide explains how to value them.

Checklist before you deposit

1. Open the case page and confirm the odds add up to 100%.
2. Calculate the EV with marketplace prices, not the site's own values, and compare it with the case price.
3. Set your own client seed before you open, and verify a few rolls after rotating seeds.
4. Read the withdrawal rules: rollover, minimums, verification, and how skin withdrawals are delivered.
5. Check how the site handles Steam trade protection on deposits and withdrawals.
6. Confirm the site is allowed where you live, and that you are of legal age.
7. Decide a fixed budget first, and stop when it is gone.

If you want a structured way to compare operators, the site trust scorecard lists the checks in one place. And if case opening stops feeling like entertainment, our responsible gambling page has tools and support links.