RTP is the house edge seen from the player's side. If a game's house edge is 4 percent, its RTP is 96 percent. Casinos and slot makers have used the term for years, and skin gambling sites borrowed it. It sounds friendlier than house edge because it talks about what comes back rather than what is taken, but it is the same number turned around.
What does an RTP number really mean?
An RTP of 96 percent does not mean you get 96 percent of your money back on a session. It means that across millions of rounds, players as a group get about 96 cents back for every dollar bet. One player can lose everything and another can win big; the average is what the RTP describes. The longer you play, the closer your own result tends to drift toward it, and since it is below 100 percent, that drift is toward a loss.
RTP also assumes the site's item values are real. On a case site, the "return" is often measured in the site's own item prices. If those prices are above what you can sell for, the effective RTP is lower than the number shown. Check a few items against the Steam Market or a marketplace before you trust a published RTP.
How do you check the RTP of a case or game?
For a case, list every item, its probability and its real resale value. Multiply each value by its probability and add them up. Divide by the case price. That is the RTP. The house edge calculator and case odds calculator automate this. For crash, coinflip or roulette, the RTP comes from the payout multiplier and the win chance, and a site that publishes a provably fair formula usually publishes the edge too.
A high RTP is less bad, not good. Even at 98 percent the expected result is a loss of 2 percent of everything wagered, and fast games rack up wagers quickly. Provably fair proves the roll was honest, not that the RTP is above 100. See the house edge guide and responsible gaming before playing.