Implied Odds From a Moneyline

A moneyline is a probability wearing a dollar sign. Read the table first, then the two rules that generate every row:

Moneyline	Implied win %	Read
-350	77.8%	heavy favorite
-200	66.7%	strong favorite
-150	60.0%	clear favorite
-110	52.4%	standard juiced line
+100	50.0%	true coin flip
+150	40.0%	moderate underdog
+200	33.3%	notable underdog
+250	28.6%	long shot

Two fractions produce all of it. For a minus price -N, the implied win chance is N / (N + 100). For a plus price +N, it’s 100 / (N + 100). That’s the entire conversion.

Why those two fractions

American prices orbit a base of 100 units. A minus sign says “risk this to win 100”; a plus sign says “risk 100 to win this.” Break-even is always risk divided by total return.

Take -200: you lay 200 to collect 100, so 200 / (200 + 100) = 66.7% — you must win two of every three tries just to stay level. Flip to +200: you risk 100 to win 200, so 100 / (200 + 100) = 33.3%, winning only one in three.

Notice -150 and +150 do not both mean 50%. The favorite side always implies more than half, and the gap between the two sides is where the house lives.

The vig hides in that gap

Add both sides of a real market and you clear 100%. The classic -110 / -110 line runs 110 / 210 = 52.38% each way, and 52.38% + 52.38% = 104.76%. That surplus 4.76% is the vig — the overround. To recover the fair, no-vig probability, divide each side by the total: 52.38% / 104.76% = 50.0%.

This is why you can’t just bet both sides and lock a profit: the prices are set so their implied numbers sum above 100%. On a lopsided line like -150 / +130, the raw figures are 60.0% and 43.5% (sum 103.5%), and the no-vig fair chance for the favorite is 60.0 / 103.5 = 58.0% — a full two points below the price’s surface reading.

Running it backward

The conversion reverses, which is how you check whether your own read is worth a bet. Turn a probability into decimal odds — decimal = 100 / prob — then read off the line:

Your estimate	Decimal	Fair moneyline
60%	1.67	-150
55%	1.82	-122
50%	2.00	+100
40%	2.50	+150
33.3%	3.00	+200

Say you rate a side at 55% but the book offers +120 (implied ~45%). You’re being paid as an underdog on a bet you consider a favorite — a large edge.

From price to a bet

Implied odds set the bar; your estimate clears it or doesn’t. A wager is +EV only when your true win probability beats the no-vig number. Price a team at -150: raw implied 60%, no-vig fair ~58%. Rate them yourself at 63%, and your edge is 63% − 58% = 5%.

Skip the devig step and that same 63% looks like only a 3% edge against the raw 60% — nearly half the real advantage — so you’ll pass on profitable bets or take ones that only look good because the margin was still baked in. It’s the pot odds instinct exactly: the offered price is a break-even threshold, and money goes in only when your real chance clears it. The poker-side reasoning lives in implied probability and the implied odds in sports betting breakdown, both in the poker odds and math hub.