EXPERIMENTAL PROTOTYPE · NOT FOR USE
This page is an unvalidated research prototype. Outputs are model projections, not betting advice, and have not been backtested or independently audited. No warranty, express or implied. Past performance does not predict future results. Sports betting carries financial risk; only those 21+ in jurisdictions where it is legal should consider wagering. For information on responsible play, see our responsible gambling page or call 1-800-GAMBLER. By viewing this page you acknowledge it is provided for evaluation and educational purposes only.
Sports Betting · 101

Betting, with pictures.

No jargon. No fake-sharp energy. Big, clear visuals that explain exactly what every number on a bet slip actually means.

Start from zero Know basics? Skip to Oddsy guide
01 · Bet anatomy02 · Odds03 · Bet types04 · Vig05 · Parlays06 · EV07 · Bankroll08 · Quiz
Start here

A bet is stake → event → payout.

You risk money on something you can't control. Right answer = book pays you. Wrong answer = they keep your stake.

$100
You put up
$100your stake
The money you risk.
NBA
Event
Lakers −4.5@ −110
The thing you're betting on. A team, a total, a player prop.
WIN
If you win
+$91profit
If you lose, you forfeit the $100.
The number that matters

Odds tell you how much it pays.

Minus (−) = favorite: lower payout, higher chance. Plus (+) = underdog: bigger payout, lower chance. The bigger the number, the more lopsided.

67%
−200
Big favorite
$200 to win $100
52%
−110
Standard line
$110 to win $100
40%
+150
Underdog
$100 to win $150
20%
+400
Long shot
$100 to win $400
The three flavors

Moneyline, spread, total.

Every game has three core markets. Pick the winner, pick with a handicap, or pick how many total points get scored.

Moneyline
Lakers−180Nuggets+155
Pick the winner, no points involved.
Lakers win outright — even by 1 point — and your bet hits.
Spread
HANDICAP LINELAL−4.5DEN+4.5
Favorite gives points. Underdog gets points.
Lakers −4.5 means they must win by 5+. Nuggets +4.5 means they can lose by up to 4 and still cover.
Total (O/U)
220.5UNDEROVER
Bet the combined score of both teams.
Total is 220. If the final is 111–112 (223), Over hits. 108–110 (218), Under hits.
The book's cut

Vig — why both sides can't be 50/50.

The book tilts every line so implied probabilities add up past 100%. That extra is how they make money.

VIG4.8%
Side A (−110 implies)52.4%
Side B (−110 implies)52.4%
Total (book's number)104.8%
Fair (what it should be)100.0%
Both sides can't really be 52.4% — that's 104.8% total. The extra 4.8% is the house edge. Oddsy strips this out so you see the true 50/50.
Big payout, small chance

Parlays multiply your bets.

Combine multiple bets into one ticket. All must win. Miss any leg, the whole ticket loses.

LEG
1
Lakers ML
55% chance
LEG
2
Celtics −6
55% chance
LEG
3
Over 220.5
55% chance
3-LEG PARLAY TRUE ODDS
16.6%
Three 55% bets — together you only hit this 17 times out of 100.
The whole game

Expected value is how winners think.

You don't need to win every bet. You need to win more often than the price says you should. That gap is called edge.

100 bets at −110, you hit 55%
55 wins45 losses
Expected profit per $100
+$5.00
That's your expected value. Positive = you're making money long-run. Negative = the book is.
Don't blow up

Bankroll, in units.

Pros stake 1–3% of their bankroll per bet. It keeps cold streaks from busting you out.

Bankroll
$1,000
1 unit
$10
Max per bet
3 units
Each square = 1% of your bankroll. Bet 1 unit on standard plays. Even sharps lose 40%+ of their bets. Units are how you survive the cold streaks.
Prove it

Quick quiz — three questions.

Tap an answer. You'll see right away if you got it.

Question 1
Lakers −4.5 at −110. You bet $100. Lakers win by 5.
Question 2
Total is 220. Final score: 111–109 (220 combined).
Question 3
Biggest payout on a $100 bet?
You're ready

Now let us do the math for you.

Every day Oddsy scans 7 books and ships only the bets where the book is paying more than the math says they should.

See today's +EV picks