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A minus price is what you stake to win 100. A plus price is what 100 wins you. So -110 means risking 110 to win 100, and +150 means 100 wins 150 — that is the whole convention, and everything else on this page is arithmetic you can check.
The number is a ratio, and the sign says which way round it is written. At -110 you put up 110 to win 100, and a winning ticket returns 210 — your stake back plus the profit. At +150 you put up 100 to win 150, and a winning ticket returns 250. The hundred is a unit, not a dollar amount: the same ratio holds whatever you actually stake.
Nothing about the bet changes with the display. Books let you switch between American, decimal and fractional because different markets grew up writing the same ratio in different ways, and a price that looks unfamiliar in one format is the same offer in all three.
A price near even money sits close to -110 on both sides of a two-way market, which is why that number turns up so often on point spreads and on player props. It is not a standard or a rule — it is where books commonly open a market they consider a coin flip, with their margin already inside it.
Implied probability is what the price would have to believe about the outcome for the bet to break even. For a minus price, divide the number by itself plus one hundred: 110 divided by 210 is 52.4%. For a plus price, divide one hundred by the number plus one hundred: 100 divided by 250 is 40%.
That is the number worth carrying around, because it is the one you can compare with anything else you know. A hit rate counted from a player’s game log is a percentage; a price is a percentage in disguise. Putting them in the same units is the entire trick behind every prop research tool, this one included.
It is not a forecast, and the word "implied" is doing real work. The figure is what the price says, not what will happen and not what the book privately believes — the margin in the next section is baked into it.
Take a market priced at -110 on both sides. Each side implies 52.4%, and the two together imply 104.8%. Probabilities of two outcomes that cannot both happen should sum to one hundred; the extra is the sportsbook’s margin, known as the vig or the hold, and it is the price of the market rather than a fee charged separately.
This is why the margin matters more on a parlay than on a single bet. Each leg carries its own slice, the slices multiply along with the odds, and a ticket assembled from legs that each look reasonable can carry a margin the individual prices never advertised. The arithmetic is the same at every book; how much they take is not, which is why the same selection can be priced differently across two of them.
Decimal odds are the total return per unit staked, so they already include the stake: -110 is 1.909 in decimal and +150 is 2.50. Converting is one step in each direction — a minus price is one hundred divided by the number, plus one; a plus price is the number divided by one hundred, plus one.
Decimal is the form parlay arithmetic actually uses. The legs’ decimal prices are multiplied together to get the ticket price, which is why a parlay calculator asks for odds in either format and converts before it multiplies. Fractional odds are the same ratio again, written as profit over stake, and are mostly a British convention.
It is not a measurement of the player, and it is not a prediction. A posted price is what one book is willing to offer right now, margin included, and it moves with money, news and lineups rather than with anything a box score has recorded.
The measured numbers on this site are the other half of that comparison and they are built the opposite way: counted from official box scores, one row per game a player actually played, with the number of games printed beside every rate. A rate without a denominator is not a measurement, and neither a rate nor a price is a forecast — past performance does not predict future results, and Parlay Builder is a research tool that does not accept wagers, hold funds or settle bets.
You stake 110 to win 100. A winning ticket returns 210 — the stake back plus the profit — and the hundred is a unit rather than a dollar amount, so the ratio holds at any stake. It is the price books commonly post on both sides of a market they treat as close to a coin flip, with their margin already inside it.
A stake of 100 wins 150, and a winning ticket returns 250. A plus price is the underdog side of a market: it pays more than it risks, and the implied probability behind it is correspondingly lower — 100 divided by 250, or 40%.
For a minus price, divide the number by itself plus one hundred. For a plus price, divide one hundred by the number plus one hundred. Both give the implied probability — what the price would have to believe for the bet to break even — and both include the sportsbook’s margin, which is why the two sides of one market sum to more than one hundred.
No. They are three ways of writing one ratio. Decimal states the total return per unit staked, American states the ratio against a hundred-unit reference, and fractional states profit over stake. A book switching your display changes nothing about the offer or the payout.
Decimal, because parlay arithmetic is multiplication: convert each leg to decimal, multiply the legs together, and the result is the ticket price. That is what a parlay calculator does whichever format you type in, and it is why the same ticket can be quoted as a long American number without any extra rule being applied.
Type legs in American or decimal odds and see the combined price and the return on your stake. Arithmetic only — it says nothing about whether a ticket is worth placing. Open the free parlay calculator.
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Odds and lines come from licensed data feeds and refresh on a schedule; hit rates, edges and grades are Parlay Builder’s own calculations.