Methodology
How SpellBook calculates Box EV
Box EV is a probability-weighted estimate of the singles value inside a sealed Magic product. It is useful because it makes the cracking decision measurable, but it is still an average, not a promise about the next box you open.
Core formula
Box EV = sum(card price x pull probability) x packs per box
EV ratio compares that number against the current sealed market price.
What EV measures
Expected value is the weighted average value of all card outcomes in a sealed product. A card that appears often contributes more than a card that appears rarely. A high-priced chase mythic matters, but only in proportion to its actual pull rate.
SpellBook Finance reports total box EV, pack EV, and EV ratio so you can compare sealed products on the same basis. The number is best used as a decision input alongside market price, buylist liquidity, fees, and your own cost basis.
For a longer walkthrough with buying examples, read the complete box EV guide.
Where card prices come from
The EV pipeline uses a consensus view instead of trusting one marketplace blindly. TCGplayer is the primary anchor, then dealer and completed-sale sources help identify outliers or thin markets.
TCGplayer
Primary market anchor for current Magic singles and sealed prices.
Card Kingdom
Retail and buylist signal that helps catch non-TCG demand.
CoolStuffInc
Dealer-side retail signal, especially useful when TCG listings are thin.
eBay sold listings
Completed-sale reality check for sealed products and scarce cards.
For the pricing methodology behind those source-level values, read the SpellBook price methodology.
How pack composition is determined
Pack composition comes from MTGJSON sealed product data and the set-level card pool SpellBook already uses for EV rankings. Each slot is modeled by rarity, treatment, and product type when that information is available.
A play booster, collector booster, draft booster, Commander deck, pack, case, and specialty product do not share one generic pull model. The pipeline uses the product type and set data to build the relevant card probability table, then multiplies the pack EV by the number of packs in the sealed product.
What's included
| Status | Input |
|---|---|
| Included | Main-set singles that can appear in the sealed product. |
| Included | Variant treatments when the product data exposes the slot. |
| Excluded | Tokens, ad cards, basic lands, and packaging inserts. |
| Excluded | Universes Beyond promos that are not part of the product's normal pull distribution. |
| Excluded | Seller fees, shipping costs, taxes, and your time to sort or list singles. |
Update cadence
Box EV is recomputed daily. Price sources refresh on their own cadence, so a newly recomputed EV uses the newest source snapshot available at that time. The box detail page shows the latest EV update timestamp next to the methodology accordion.
During previews and prerelease windows, EV can move sharply as more cards receive stable market prices. SpellBook labels preliminary EV when price coverage is incomplete.
Known limitations
- Pre-release and launch-week products can be unstable because card prices and supply are still discovering a market.
- Marketplace spreads matter. EV uses market prices, but your realized exit depends on liquidity, condition, and fees.
- Pack collation is modeled from available product data. If Wizards changes a slot or publishes incomplete details, EV can lag until data catches up.
- EV is an average over many boxes. One box can still be cold or hit a chase card far above EV.
- Opportunity cost of capital is not included. Holding sealed product ties up money, space, and attention.