The formula, without ceremony
Pack EV is the sum over every possible hit of its rate per pack times its average market value, plus the average value of the bulk cards. Here is a fully illustrative example with invented numbers. A 4 dollar pack has a 1 in 50 chance at an 18 dollar card, a 1 in 150 chance at a 60 dollar card, and a 1 in 400 chance at a 200 dollar card, with about 35 cents of bulk. That is 0.36 plus 0.40 plus 0.50 plus 0.35, for an EV of about 1.61 dollars.
Notice that the example pack costs 4 dollars and carries about 1.61 dollars of expected contents. That relationship is normal. Sealed product from a publisher usually has an EV below its price, because part of what you pay for is the experience, distribution, and the publisher's margin. When raw EV climbs near or above pack price, it is usually temporary and the market corrects it.
EV is an average, not a promise
EV describes what an enormous pile of packs averages out to. Your one pack does not get an average, it gets an outcome. The distribution of pack outcomes is heavily skewed. The typical pack is worth well under EV, and a small fraction of packs contain the big hits that drag the average up. Opening one pack and comparing it to EV is like judging a lottery by one ticket, except with better art.
This is why EV close to pack price still does not mean you will break even. Over hundreds of packs your results drift toward the average. Over five packs, anything can happen and usually the boring thing does. We built a parody church on this distinction, so we take it seriously.
Market prices move, so EV moves
Every EV figure is a snapshot. Card prices swing with reprints, tournament results, rotation, hype cycles, and supply waves, so the EV of a product drifts week to week. A set that looked rich at release often deflates as more product is opened and supply grows. Any EV number without a date attached is a rumor.
Also mind the gap between market price and money in hand. Selling your pulls means fees, shipping, condition downgrades, and time. The cash you can actually extract from a pile of pulls is meaningfully below their listed market value. EV math done with sale prices you can realistically get is always uglier and always more honest.
How to actually use EV
EV is a comparison tool, not a treasure map. Use it to compare products, like whether a special set or a standard set gives more expected contents per dollar, or whether a box beats loose packs at current prices. Use it to calibrate expectations before opening so the results do not surprise you. Use it to notice when chasing a single card through packs is wildly worse than buying the single, which is nearly always.
Do not use EV as investment advice, because it is not, and we do not give any. Opening sealed product is entertainment with a partial rebate, not a yield strategy. The pack gods hold no positions and neither should your rent money.