How the odds converter works
A sports betting odds converter translates one quoted price into
every other format you might see. The four formats below all
describe the same wager. They just look different depending on
whether you're betting in the US, Europe, the UK, or thinking in
probability. Here's what each one means and how to convert it by
hand.
American Odds Converter (Moneyline)
American odds, also called moneyline odds or US odds, are the
standard format used by Vegas sportsbooks and every US-licensed
book. A line is written as a positive or negative integer such as
+150 or -200. A positive number is the
profit you'd win on a $100 stake. A negative number is the amount
you'd need to risk to win $100.
At +150 you risk $100 to win $150 (total return $250).
At -200 you risk $200 to win $100 (total return $300).
Even money is +100, risk $100 to win $100. Anything
better than +100 is an underdog; anything worse than
-100 is a favorite.
How to convert American odds to decimal:
for a positive line, divide by 100 and add 1
(+150 -> 2.50). For a negative line, divide 100 by the
absolute value and add 1 (-200 -> 1.50).
Decimal Odds Converter (European)
Decimal odds, sometimes called European odds, are the standard
in Europe, Australia, and on betting exchanges. They are also the
format every betting model and exchange uses internally because
the math is trivial. A decimal price is simply your total return
per unit staked.
Bet $100 at decimal 2.50 and a winner pays back
$250 ($150 profit plus your $100 stake). Bet $100 at
1.91 and you get $191 back. This is the European
equivalent of the US -110 standard juice on a point
spread.
Anything below 2.00 is a favorite. Anything above
2.00 is an underdog. Exactly 2.00 is even
money. How to convert decimal odds to American:
if the decimal is 2.00 or higher, subtract 1 and multiply by 100
(2.50 =+150). If it's below 2.00, compute
-100 / (decimal - 1) and round
(1.50 =-200).
Fractional Odds Converter (UK & Horse Betting)
Fractional odds are the traditional format at British racetracks
and the default at most UK bookmakers. They are still the
standard way horse betting odds are displayed. A line is written
as a fraction -3/2, 5/1,
1/2, representing the ratio of profit to stake.
At 3/2, every $2 staked returns $3 in profit, plus
your $2 stake back. So a $100 bet at 3/2 wins $150 in
profit and pays out $250, identical to American
+150 and decimal 2.50. At
1/2 (read "one-to-two on") you must risk $2 to win
$1; this is a heavy favorite.
How to convert fractional odds to decimal:
divide the numerator by the denominator and add 1
(3/2 -> 1.5 + 1 = 2.50). The added 1 represents your
stake being returned alongside the profit.
Odds to Probability Converter (Implied Probability)
Implied probability is the most useful number in betting. It is
what the price says the chance of the outcome is, and the
only number worth comparing against your own estimate of fair
value. An odds-to-percentage converter and a probability-to-odds
converter are really the same tool. They just run the formula in
opposite directions.
The formula is p = (1 / decimal) * 100%. A line of
2.50 implies a 40% chance. A line of 1.50
implies 66.67%. +100 (decimal 2.00)
implies exactly 50%. To go the other way, divide 100 by the
percentage to get the decimal odds
(40% -> 100 / 40 = 2.50).
The implied probabilities on both sides of a market do
not sum to 100%. They sum to more, and the
excess is the sportsbook's margin (the vig, explained below).
Subtracting the vig gives you the "fair" or "no-vig" implied
probability, which is what you should compare against your own
estimate when looking for value.
Payouts, vig and finding value
Calculating your payout (odds to money)
Payout math is easiest with decimal odds. Multiply your stake by
the decimal and you have your total return. Subtract the stake
and you have your profit. A $50 bet at 3.00 returns
50 * 3.00 = $150, $100 profit on $50 risked.
In American odds the formula depends on the sign. For a positive
line, profit = stake * (american / 100). For a
negative line,
profit = stake * (100 / |american|). A $50 bet at
+200 wins $100; the same stake at -200
wins $25.
What the vig (juice) is and why it matters
Sportsbooks make money by quoting prices that imply a combined
probability of more than 100%. The excess is called the vig,
juice, or overround.
A standard NFL point spread is offered at -110 on
both sides. The implied probability of -110 is
52.38%, so the two sides sum to
52.38% + 52.38% = 104.76%. That extra 4.76% is the
book's margin. To estimate the "fair" probability on either side,
divide its implied probability by the total:
52.38 / 104.76 = 50.00%, exactly what you'd expect
from a coin flip.
Positive expected value (+EV)
A bet has positive expected value when your estimate of the true
probability exceeds the no-vig implied probability of the
offered line. If a market is priced at +150 (40%
implied) and you model the true chance at 45%, the bet has
roughly (0.45 * 2.50) - 1 = 12.5% expected value per
unit staked. Long-term profit comes from systematically paying
less than fair value, not from picking winners.
Frequently Asked Questions
What is a betting odds converter?
A betting odds converter is a calculator that translates a price
between formats: American (moneyline), Decimal (European),
Fractional (UK), and Implied Probability, so you can compare
lines across sportsbooks and exchanges regardless of how they
display the odds.
What is the easiest odds format to understand?
Decimal. The number is your total return per unit staked, so
$100 at 2.50 pays $250. There's no positive/negative
branching like American odds and no fraction parsing like UK
odds. It is also the format every betting model and exchange
uses internally.
What do +150 odds mean?
A line of +150 means you win $150 in profit on a
$100 stake. Including your stake back, the total payout is $250.
In decimal that is 2.50; in fractional,
3/2; in implied probability, 40%.
What do -110 odds mean?
A line of -110 means you must risk $110 to win $100.
This is the standard juice on point spreads at American
sportsbooks. In decimal it is roughly 1.909; in
fractional 10/11; the implied probability is 52.38%.
How do I convert American odds to decimal?
For positive American odds, divide by 100 and add 1:
+250 -> 2.50 + 1 = 3.50. For negative American odds,
divide 100 by the absolute value and add 1:
-250 -> 0.40 + 1 = 1.40.
How do I convert decimal odds to American?
If the decimal is 2.00 or greater, subtract 1 and multiply by 100
to get the positive American line. If it is less than 2.00,
compute -100 / (decimal - 1) and round. So
2.50 =+150 and 1.50 =-200.
How do I convert fractional odds to decimal?
Divide the numerator by the denominator and add 1.
3/2 -> 1.5 + 1 = 2.50. The added 1 represents your
stake being returned alongside the profit.
How do I convert odds to a percentage (probability)?
Convert to decimal first, then take 1 / decimal * 100.
So +150 -> 2.50 -> 1 / 2.50 = 40%. To go the other
way (percentage to odds), divide 100 by the percentage:
40% -> 100 / 40 = 2.50 decimal.
Are American and Vegas odds the same thing?
Yes. "Vegas odds," "US odds," and "moneyline odds" all refer to
the same American format: the positive/negative integer style
quoted by every US-licensed sportsbook.
Why don't the implied probabilities add up to 100%?
Because the sportsbook adds a margin. The implied probabilities
on both sides of a market sum to more than 100%, and the
difference is the vig. Divide each side's implied probability by
the total to get the "fair" or "no-vig" probability.
Are higher odds better?
Higher odds pay more per dollar risked but indicate a lower
probability of winning. A line of +500 implies only
a 16.67% chance; -500 implies 83.33%. The right
question is not "are the odds high" but "are the odds higher
than they should be."
What is the break-even win rate?
Break-even is the win rate at which a bet at a given price
neither makes nor loses money over the long run. At decimal
2.00 you need to win 50% of the time. At
-110 you need 52.38%. At +200 you only
need 33.33%.
Does this site take wagers?
No. odds-converter.net is a free informational tool. It
performs format conversion and payout math only. It does not
accept, place, or facilitate wagers of any kind.
Glossary
The betting terms used on this page, defined plainly.
- Moneyline
- A bet on the outright winner of a match, priced in American odds.
- Juice / Vig
- The sportsbook's built-in margin. Causes implied probabilities to sum above 100%.
- Overround
- The total of all implied probabilities in a market minus 100%. Equivalent to the vig.
- No-vig price
- The fair odds derived by removing the book's margin proportionally from each side.
- Favorite
- The side with the higher implied probability: decimal < 2.00, American with a minus sign.
- Underdog
- The side with the lower implied probability: decimal > 2.00, American with a plus sign.
- Even money
- A line of decimal
2.00, American +100, fractional 1/1.
- Stake
- The amount risked on a bet.
- Total return
- The amount paid back on a winning bet: stake plus profit.
- Break-even
- The minimum win rate required for a price to be profitable over the long run.
- Expected value (EV)
- The average profit per unit staked, given a true probability estimate.
- Closing line
- The final price offered before a market closes. Considered the sharpest estimate of fair odds.