H2H (head-to-head / moneyline)
A two-way market on which side wins outright, with no point spread — the sportsbook term is moneyline, the odds-feed key is h2h.
H2H stands for head-to-head. It is the simplest market a book offers: pick the winner. In American odds a favorite is quoted with a minus sign (−150 means risk $150 to win $100) and an underdog with a plus (+130 means risk $100 to win $130). Odds feeds and APIs call this market 'h2h'; US books call it the moneyline.
Because both sides are priced by the same book, their implied probabilities sum to more than 100% — the excess is the vig. Comparing h2h prices across books is where most cross-book arbitrage on winners is found, and ArbMonster measures each book's h2h margin continuously.
Twins −120 at one book, Padres +135 at another. Implied probabilities 54.5% + 42.6% = 97.1% — under 100%, so a stake split across both books returns more than it costs whichever team wins.
Measured on ArbMonster: Sportsbook margins by market
Related terms: Moneyline · Point spread · Total · Vig · Implied probability