To compare a case's price with what's inside it, calculate its expected value (each item's value × its drop chance, summed), divide by the price to get the return to player, and then adjust for what you can actually get for the items. The gap between the price and that adjusted figure is the average cost of each opening.
The case thumbnail shows the most valuable item. The price is set against the average item. This guide shows how to measure the distance between the two.
Three numbers you need
| Number | Formula | Tells you |
|---|---|---|
| Expected value (EV) | Σ (item value × drop chance) | Average value per opening, at site prices |
| Return to player (RTP) | EV ÷ case price | Share of the price returned on average |
| Realistic return | EV × sell-back rate ÷ case price | Share returned if you convert items back to balance |
House edge is simply 1 − RTP. A 92% RTP means an 8% house edge.
A worked example (fictional)
This $3.50 case has seven items. Everything about it is invented for the example — the method is what matters.
| Item | Value | Drop chance | Value × chance |
|---|---|---|---|
| Item A | $400.00 | 0.05% | $0.2000 |
| Item B | $85.00 | 0.45% | $0.3825 |
| Item C | $30.00 | 1.50% | $0.4500 |
| Item D | $11.00 | 6.00% | $0.6600 |
| Item E | $4.20 | 17.00% | $0.7140 |
| Item F | $1.80 | 30.00% | $0.5400 |
| Item G | $0.60 | 45.00% | $0.2700 |
| Total | 100.00% | $3.2165 |
First, check the chances: 0.05 + 0.45 + 1.5 + 6 + 17 + 30 + 45 = 100%. Good.
Now the three numbers:
- EV = $3.2165, about $3.22 per opening.
- RTP = 3.2165 ÷ 3.50 = 91.9%, so the house edge is 8.1%.
- Average loss = $3.50 − $3.2165 ≈ $0.28 per opening.
Adjusting for the sell-back rate
Suppose this fictional site buys items back at 85% of their listed value. If you plan to convert drops back into balance, your realistic return is:
- $3.2165 × 0.85 = $2.73 per opening
- $2.73 ÷ $3.50 ≈ 78.1% realistic return
The "8% edge" case becomes a roughly 22% average cost once you account for how you exit. This is the most commonly missed step in EV discussions.
What 100 openings looks like on average
| Measure | Per opening | × 100 openings |
|---|---|---|
| Spent | $3.50 | $350.00 |
| Expected value at site prices | $3.22 | $321.65 |
| Expected value after 85% sell-back | $2.73 | $273.40 |
| Average shortfall after sell-back | $0.77 | $76.60 |
Real results over 100 openings will scatter widely around these averages — see variance and streaks for how widely.
Where the value is concentrated
Look at which items carry the EV:
- Item A — the one on the thumbnail — contributes $0.20, only about 6% of the EV.
- Items D, E and F together contribute $1.91, nearly 60% of it.
- Item G drops 45% of the time and is worth $0.60 — about one-sixth of the price.
Add up the chances of items worth less than $3.50 (F and G): 75%. Three openings in four return less than the case costs.
Item E, at $4.20, is technically "above the price", but after an 85% sell-back it converts to $3.57 — only 7 cents more than you paid. In practice, "winning" on this case means Item D or better, which is an 8.00% combined chance (0.05 + 0.45 + 1.5 + 6).
Why the listed item values may not be real
The EV is only as good as the values plugged into it:
- Site-set values. The value shown is chosen by the site. It may be above what an outside market would pay.
- Wear conditions. The same item can vary a lot in price by wear. Check which version the value refers to.
- Stale prices. Item prices move. A case set up when an item was expensive may now be overvalued in its own table.
- Withdrawal limits. If you cannot withdraw an item (out of stock, minimums, holds), its "value" may only be usable as site balance.
When in doubt, use the lower number: the sell-back value, or an outside market price minus that market's fees.
Comparing two cases fairly
When you compare cases, compare like with like: the realistic return (after sell-back) and the chance of getting less than the price back. A cheaper case with a higher RTP can still have a higher chance of a below-price result. Neither number alone tells the whole story, so look at both.
A quick routine for any case
- Copy the odds table into a spreadsheet: item, value, chance.
- Add a column for value × chance and sum it. That's the EV.
- Divide by the price for RTP.
- Multiply EV by the site's sell-back rate for a realistic return.
- Sum the chances of items below the price.
If you cannot complete step 1 because the site does not publish full odds, you can't evaluate the case at all — one of the items on our pre-deposit checklist. If you are new to tables, start with how to read a case odds table.
The takeaway
A case is priced above its average contents, by design. EV and RTP tell you by how much; the sell-back rate tells you how much more. None of those numbers can turn a negative-value draw into an investment. Budget for the loss, treat any win as luck, and use the tools on our responsible gambling page if you need them.
FAQ
What is expected value in case opening?
Expected value is the average value of one opening over a very large number of openings. You get it by multiplying each item's value by its drop chance and adding the results.
If the expected value is $3.22 and the case costs $3.50, will I lose 28 cents each time?
No. Any single opening returns one item, often far below the case price and occasionally far above it. The 28 cents is the average loss per opening over many openings, not what happens on each one.
Why should I use the sell-back rate in the calculation?
Because the value shown on the site is not always what you can turn an item into. If the site buys items back at 85% of listed value, your realistic return is 85% of the expected value, not 100%.
Does a high return to player mean a case is worth opening?
It means you lose money more slowly on average, nothing more. Every case priced above its expected value loses money over time, whatever the percentage.