What does +400 mean in sports betting? An expert data analyst‘s explainer

As an avid sports bettor and data analyst, I‘m often asked to explain what the different betting odds like +400 or -110 mean. I‘ll walk through the common types of bets and odds step-by-step in this complete beginner‘s guide.

Introduction: Reading sports betting odds

Sportsbooks use odds like +400, -200, or +3.5 alongside teams to show the payout or risk amount for different bets. They also indicate which team is favored to win or cover the spread.

Learning how to read these sports betting lines is crucial for beginners. I‘ll explain what the plus and minus signs mean, how moneylines work, spreads, over/unders, and more. You‘ll know how to interpret odds and become a smarter bettor.

Here are the key points we‘ll cover:

  • Moneyline odds
  • Point spreads
  • Totals (over/under)
  • Implied probability and vig
  • Live betting
  • Payout calculations
  • Finding value bets

By the end, the common terminology and math logic behind betting lines will make way more sense. You‘ll gain the confidence to analyze odds and place smarter wagers.

Moneyline odds

The most basic wager is the moneyline, where you simply bet on a team to win straight up with no point spread. Oddsmakers assign either a plus or minus sign to indicate the favorite and underdog:

  • The minus (-) indicates the favorite
  • The plus (+) shows the underdog

For example:

New England Patriots -250
Miami Dolphins +195

The Patriots are expected to win as -250 favorites. The +195 means the Dolphins are underdogs.

But what do those numbers mean specifically?

The number shows the amount you must risk or will profit based on a $100 bet.

  • Bet $100 on the favorite at -250 odds, and you‘ll net $40 profit if they win (+$140 total payout – $100 bet = $40 profit)
  • Bet $100 on the underdog at +195, and you‘ll net $195 profit if they win (+$295 payout – $100 bet = +$195 profit)

The favorite must risk more for the chance at a smaller profit. While underdogs offer a larger return for the higher risk.

Some key moneyline concepts:

  • Odds above +300 (like +450 or +1600) indicate a major underdog
  • Heavy favorites below -300 (like -550) are expected to win handily
  • A "pick‘em" with no favorite has -105 or -110 odds for both sides

Now let‘s calculate payouts on some other hypothetical moneyline bets:

  • Bet $50 on a team at +250 odds
    • Wins $125 profit (+$250 x 50% bet)
    • Collect $175 total ($125 profit + $50 bet returned)
  • Bet $75 on a team at -180 odds
    • Wins $41.67 profit (-180/75)
    • Collect $116.67 ($41.67 + $75 bet)

Getting comfortable with moneyline odds is key. But next we‘ll look at point spreads, which account for margin of victory.

Point spreads

While moneylines only concern the outright winner, point spreads factor in the final margin of victory. Also called handicaps, they level the playing field by giving the underdog a lead before the game even starts.

For example, a game between the Bills and Jets might show:

Buffalo Bills -6.5 (-110) 
New York Jets +6.5 (-110)

The Bills need to win by 7+ points to "cover" the spread as 6.5-point favorites. The Jets must either win outright or lose by 6 or fewer points to cover as 6.5-point underdogs.

If the favorite covers the spread, it‘s called covering the handicap or winning against the spread (ATS). If the underdog covers, it‘s called beating the spread.

Here are some key points about spreads:

  • The favorite has a minus (-) spread showing how many points they must win by
  • Underdogs get a positive (+) spread as their head start margin
  • Standard spreads are usually set at 0.5 or 3 points to avoid a tie (push)
  • A -110 vig is charged on each side as the sportsbook‘s commission

Let‘s look at a spread example in action:

New England Patriots -7 (-110)
Buffalo Bills +7 (-110) 

Final Score: 
Patriots win 27-20

The Patriots won by 7 points, exactly covering the -7 spread. Anyone who bet on New England -7 wins their bet. The Bills lost by 7, which is equal to the +7 spread they were getting. So Bills +7 bets would also cash in this scenario.

What if the Patriots had won 23-20? Then the Patriots fail to cover as 3-point favorites. But the Bills cover the +7 spread in a losing effort. Bettors on the Bills +7 would win their wagers.

This demonstrates how spread betting lasts until the final whistle, rather than just picking the moneyline winner.

Next up, we‘ve got totals betting, also known as over/unders.

Over/Under: Betting totals and scoring

While spreads focus on margin of victory, over/under bets look solely at the combined scores of both teams. Also called game totals or totals betting, sportsbooks predict what they think the final total score will be and you simply bet whether it finishes over or under that line.

The standard totals line is set around 43 to 45 points in the NFL and 220 to 230 points in the NBA, for example. But it varies drastically sport-to-sport and game-to-game based on the matchup, teams‘ stats, weather forecasts, injuries, and various factors.

Let‘s take an NFL over/under line:

Los Angeles Chargers vs Kansas City Chiefs
Over/Under Total Points Scored: 49.5

You‘d bet whether you think the two teams will combine to score over or under 49.5 total points. It doesn‘t matter which team wins or what the final score is, as long as the total points adds up to over or under 49.5.

Key over/under principles:

  • Bettors tend to favor overs, so books shade lines slightly lower
  • Injury news can cause totals to move up or down
  • Bad weather typically lowers totals
  • High-scoring matchups see higher totals, while defensive matchups get lower totals

The vigorish (-110) also applies to totals betting. Let‘s walk through an over/under example:

Dallas Cowboys vs New York Giants
Total Points Line: 42.0

Final Score:
Cowboys 24, Giants 19
Total Points Scored = 43 

The combined score went OVER 42 total points

So an over 42 bet would cash here, while the under 42 loses. Bettors backing the over got to 43 points, clearing the 42-point total bet on.

Now that you‘ve got a handle on moneylines, spreads, and totals, let‘s examine how sportsbooks actually come up with these odds and numbers.

How oddsmakers create betting lines

Professional oddsmakers at sportsbooks analyze upcoming games and set the initial betting lines. Their goal is to attract equal action on both sides for any matchup.

For high-profile games, oddsmakers may look at various factors like:

  • Overall team records and stats
  • Player injuries and roster changes
  • Historical head-to-head results
  • Situational analysis (road vs home, off a bye week, etc)
  • Advanced metrics and simulations
  • Public perception and betting market activity

The oddsmakers use their expertise to set fair odds that aim to get split betting action. This allows the sportsbook to profit from the natural commission built into the odds.

Once the opening lines are set, the betting market takes over. Shifting public sentiment and sharp action from pro bettors causes odds to fluctuate leading up to game time.

Sportsbooks adjust the odds and lines accordingly to balance their risk exposure on each side. Their goal is to have equal money on both sides of a game.

For example, if 70% of bets are flooding in on the Chiefs -6.5 against the Broncos, the line might move to Chiefs -7.5 to entice more underdog Denver +7.5 bets.

Moving lines is the sportsbooks‘ way of defending themselves against one-sided action. It helps them reduce potential payouts and secure their profit margins.

This fluid line movement is why it‘s so important to shop for the best odds and pounce at the right time before the line moves against you.

Converting odds to implied probability

One advanced concept to understand is converting betting odds into percentages to show the implied probability of an outcome occurring.

This helps sharpen your line shopping and betting strategy by revealing if teams are overvalued or undervalued by the odds.

Let‘s walk through the formulas:

Moneyline odds to percentage

  • Take the moneyline decimal odds (always 100 or greater)
  • Divide 1 by the decimal odds to get the implied probability percentage.

For example, -200 favorite odds convert to:

1 / 2.00 = 0.50 = 50% implied probability

Negative spreads and totals to percentage

  • Take 100 and divide by the line minus 100
  • So for -110 convert to:
    • (100 / (110 – 100) = 100 / 10 = 10%
  • For -350 odds convert to:
    • (100 / (350 – 100) = 100 / 250 = 25%

Positive spreads and totals to percentage

  • Take the line divided by the line plus 100
  • So +250 odds convert to:
    • (250 / (250 + 100) = 250 / 350 = 71.4%

This shows how the +250 underdog has a much higher perceived probability (71.4%) than the -350 favorite‘s 25% chance.

Converting odds to percentages reveals when the public perception doesn‘t match reality. You can gain betting value by noticing trends and capitalizing when the odds are misaligned from teams‘ actual chances.

Live, in-game betting

Sportsbooks also offer updated live betting lines as games are underway. This is called in-game or in-play wagering. Oddsmakers quickly adjust the point spreads, totals, and moneylines on the fly to account for what‘s happening in real-time during gameplay.

For example, if the favored team goes down 14-0 early, they might become underdogs on the live betting lines until they close the gap. The totals could also drop if it‘s a slow start to the game with stingy defense.

There are many strategic opportunities with live betting by reacting to changing game situations. Key scenarios where live lines commonly shift include:

  • One team races out to a big lead or falls behind early
  • Star players get injured or ejected from the game
  • Unexpected defensive struggles or breakout performance
  • Exciting back-and-forth scoring pace causing totals adjustments

The key with live betting is being able to analyze the action and make quick decisions before the sportsbooks adjust the odds back to equilibrium.

The most crucial betting skill is being able to spot value opportunities where the true odds differ from what sportsbooks posted. This allows you to maximize your edge.

Ask yourself:

  • Do I actually think this team has a 60% chance to win or cover despite being +180 underdogs?
  • Is the total set too high or low based on these teams‘ play styles and the game situation?

Uncovering value involves predicting when the public perception or oddsmakers made a mistake pricing a team too high or low. You then place bets at inflated odds that exceed the true probabilities.

Some common value betting angles to watch:

  • Fading or backing clicking teams on hot/cold streaks
  • Major lineup changes like star players resting or returning from injury
  • Betting against the public when your research disagrees
  • Stylistic mismatches between teams
  • Taking advantage of advanced stats and metrics that oddsmakers overlook
  • Factor in motivation like one team fighting for a playoff spot late in the season

Line shopping across multiple sportsbooks to find the best odds and price discrepancies is also key. Over the long run, consistently betting only on valuable spots leads to profitable outcomes.

I hope this complete overview demystifies how to read and understand sports betting odds. Here are the main points to remember:

  • Plus (+) odds indicate underdogs, minus (-) odds are favorites
  • Moneyline provides the payout profit calculation on a $100 bet
  • Spreads set a margin of victory handicap on each team
  • Over/under totals are the combined predicted game scores
  • Sportsbooks aim for equal money on both sides to profit from the natural juice
  • Look for value bets where the true odds differ from the posted odds

With the fundamentals of betting lines mastered, you can bet on sports smarter and gain an analytical edge. Don‘t hesitate to reach out with any other sports betting questions!

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