How to Calculate Expected Value (ROI) of a CS2 Case: A Simple Worked Example

To calculate the expected value (EV) of a CS2 case, multiply each rarity tier's drop chance by the average price of the skins in that tier, then add the results. ROI is EV divided by what you paid (case plus key), minus 1. For a Kilowatt Case, SteamAnalyst's case page showed about $2.60 per opening and about $0.72 back in items on 20 October 2026, an ROI of about −72%.

This guide builds the calculator step by step and works one example with dated prices. It also shows why one lucky knife says nothing about your next thousand openings.

What do EV and ROI mean for a case opening?

Expected value (EV) is the average payout per opening if you could repeat it a huge number of times. Nobody opens a million cases, so EV describes the long-run average, not your next opening.

ROI (return on investment) compares that average with your cost:

ROI = (EV − cost) ÷ cost

An EV of $0.51 on a $2.58 opening is an ROI of about −80%. You get back roughly 20 cents of item value per dollar spent, before any selling fees.

The cost of a Valve opening is the case price plus the key. The key is $2.49 in the US in-game store, the same for every weapon case (it varies by region). Keys bought since October 2019 are bound to your account and can't be traded or sold.

That makes the key the bulk of a cheap opening. For a Kilowatt Case at about $0.09, the key is roughly 96% of the bill.

What is the formula, and what are the odds?

The formula is EV = Σ (tier chance × average price of skins in that tier). Standard weapon cases share one set of odds, which Valve disclosed in 2017 and which are the same for every case.

Inside a tier, every skin is equally likely. In a tier with two Coverts, each drops 0.32% of the time. So your tier average is the plain mean of that tier's skin prices.

Four adjustments turn a rough estimate into a useful one:

1. StatTrak. About 10% of weapon and knife drops are StatTrak, and gloves never are. Price a tier as 0.9 × normal price + 0.1 × StatTrak price. Some trackers leave StatTrak out, which makes their figures err slightly low.
2. Wear. Each skin has its own float range, so some wears can't drop and the rest aren't equally likely . Either weight each wear by its drop odds or use one wear, such as Field-Tested, for every skin.
3. Selling fees. The Steam Community Market takes a 5% transaction fee plus a 10% fee for CS2, so a buyer paying $115 leaves you $100. Each fee has a $0.01 minimum, so penny skins lose a bigger share. Proceeds are Steam Wallet funds, which can't be withdrawn as cash.
4. Price quality. Use recent sale or median prices, not the lowest listing on a thin market. A skin listed at $80 that sells twice a week isn't worth $80 in your EV.

This applies to keyed weapon cases. Souvenir packages, Armory items and sticker capsules use different odds.

Worked example: what is a Kilowatt Case worth to open?

On 17 October 2026, cs2skinprices priced every Kilowatt Case item and put an opening at about $2.58. That is a case at $0.087 plus the $2.49 key.

The case has 17 weapon skins (7 Mil-Spec, 5 Restricted, 3 Classified, 2 Covert) plus 13 Kukri Knife finishes in the gold slot. The prices below are the lowest marketplace listings in Field-Tested, with no StatTrak premium. They are a snapshot, and prices move daily.

ROI = ($0.51 − $2.58) ÷ $2.58 ≈ −80%. If you then sold everything on Steam, fees would cut the figure further.

Trackers disagree on the exact number because they price wear, StatTrak and thin markets differently. They agree on direction:

Key takeaway: Every tracker puts the Kilowatt Case at roughly 20–31 cents back per dollar spent. The spread comes from method, not arithmetic. Across all 42 cases in cs2price's August 2026 ranking, the best returned 79.5% of its cost and the worst 30.4%.

Why does the knife slot distort ROI, and why is the typical result worse than the average?

The gold slot is a lottery ticket that props up the average. In the example above, the Covert and knife rows make up about two-thirds of the EV, yet they land in fewer than 1 in 100 openings.

The 13 Kukri finishes range from about $38 to about $390 on SteamAnalyst's Kilowatt page. Valve doesn't publish odds per finish, so you can't price the gold slot precisely. Across all cases, cs2price found gold delivers on average about 29% of a case's EV, and 53% for Dreams & Nightmares.

That is why the average is not the typical result. cs2price simulated 200,000 openings per case and found the median opening is 5–25 times lower than the average. For the Kilowatt Case the median was about $0.06 on a $2.60 cost. TradeIt's separate estimate is a $0.09 median, with about a 4% chance of beating the opening cost.

When you see a headline ROI, ask how much of it rests on gold. Remove the knife row and the return you would feel in most sessions drops sharply.

How much do results swing over 10, 100 and 1,000 openings?

Short runs swing wildly around EV, and long runs converge on it. The table uses the worked-example numbers above. The "±" column is one standard deviation, computed from tier averages only. Real swings are a little wider, and the distribution is lopsided, with most sessions below the average and a few far above.

• At 10 openings, most sessions end with a few dollars of blues and purples. One Covert at about $26 roughly covers the whole spend, but that happens in under 9% of sessions.
• At 100 openings, even a result one SD above average is about $89, around a third of the $258 spent.
• At 1,000 openings, results cluster near $512 against $2,580 spent. Averaging out means losing about what the ROI says.

A knife every 385 openings is only an average. The chance of at least one knife in 385 openings is about 63%, not 100%. Each opening is independent, so a dry streak never makes the next one "due".

How do you track your own openings without chasing losses?

Tracking helps only if it makes you stop earlier, not play longer.

• Log every opening. Record date, container, cost (case plus key) and the item's value at the time, then compute a running ROI.
• Use simulators for the odds, not for hunches. SteamAnalyst's simulator tracks your simulated ROI as you open and shows it drifting toward the calculated EV.
• Don't read meaning into small samples. A run of 50 or 600 openings that looks better or worse than expected is normal randomness, not proof the odds changed.
• Set the stop rule first. "I stop when the budget is gone" works. "I stop when I'm back to even" is loss-chasing.

If you want one specific skin, buying it directly almost always costs less than the expected spend to unbox it. SteamAnalyst's case pages make the same point.

How does the calculation work on CSDROP?

CSDROP cases are not Valve cases, so don't reuse the 0.26% knife figure or the key cost from this article. CSDROP cases open from your balance with no key. Each case page shows its item pool and drop rates before you open it. Use those listed rates in the same formula.

For item values, pick one price source and apply it to every item in the pool. Items won are credited to your balance at market value. The formula becomes:

House edge ≈ 1 − (EV ÷ case price)

A real-money case site is a business, and the EV of a paid case is expected to sit below its price. That gap is the house edge, the same concept as the key and fee drag above. Prices and odds change, so check each case before you open it instead of assuming.

CSDROP is provably fair. Case openings and games use HMAC-SHA256 from a server seed (shown hashed before play), your client seed and a nonce. You can verify results from the game history. Provably fair proves a result wasn't altered. It does not change the odds.

To see how an opening works before spending, new accounts get free cases with no deposit needed. You may first have to verify your email or link Discord or Steam.

What does a responsible-play checklist look like?

Case opening is entertainment with a negative expected return, not income or an investment.

• Set a fixed budget you can afford to lose completely, plus a stop-loss and a time limit before you start.
• Never open with rent, bills or borrowed money.
• Don't reopen to "win it back". That's the gambler's fallacy.
• After a big win, don't reinvest all of it.
• If control slips, stop, and talk to a local gambling support service.

CSDROP is for adults only: 18+, or the age of majority in your country if higher. Play responsibly. No outcome is guaranteed.

FAQ

What is a good ROI for a CS2 case?

None is positive on average. In cs2price's August 2026 ranking of 42 cases, the best returned 79.5% of its cost and the worst 30.4%. Treat anything near the top as "least bad", and remember that selling on Steam costs a further share.

Are the odds the same for every CS2 case?

Standard weapon cases share the same rarity odds: 79.92%, 15.98%, 3.20%, 0.64% and 0.26%. Only the skins in each tier change, which is why EV differs between cases. Souvenir packages, Armory items and sticker capsules use different odds. On CSDROP, use the rates shown on each case page.

Does the key matter more than the case price?

For budget cases, yes. The key is $2.49 in the US regardless of the case, so a case worth under $0.10 still costs about $2.58 to open. Always cost an opening as case plus key.

Is buying the skin cheaper than opening cases for it?

Usually, yes. Buying a skin directly costs its market price, while unboxing it means paying the whole expected loss on many openings first. Opening is about the experience, not the price.

Do dry streaks make a knife more likely?

No. Each opening is independent, so a long run of blues doesn't raise the next chance. The 1-in-385 figure is an average, and even after 385 openings there's roughly a 37% chance of no knife.

How do I verify a result on CSDROP?

CSDROP is provably fair, so you can check results from the game history using the server seed (shown hashed before play), your client seed and the nonce. The provably fair page explains the method. Try it on a few of your own openings so you know how it works.