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Sports Betting FAQ: Your complete Betting 101 (All Terms explained!)

Find all the answers in our comprehensive Betting Glossary

If you are new to sports betting, or perhaps just less familiar with +EV Betting, this FAQ should help answer some of your questions. When we make our picks, whether you're a subscriber in our discord or a follower on Twitter @PromoGuyUS, understanding the contents of this document will help you get all that you can out of our profitable system.

The first part of this page serves as a glossary, while the second part has some FAQs with concrete examples. At PromoGuy, our goal is not only to provide you with free picks to follow, but also give you the tools you need to analyze odds and promotions and make picks for yourself!


  • EV - expected value
  • ROI - return on investment
    • These two terms are very similar and often mis-used
    • When we say “+8% EV” for example, we really mean our expected ROI is +8%. EV is technically a number (+8% Expected ROI on a $50 wager would be an EV of $4)
  • Vig - the amount of “hold” that the sportsbook takes as a commission for accepting a wager. The higher the vig, the higher percentage of money that the house is keeping
    • Also known as “juice”
  • Mainline - a wager on either the spread, moneyline, or total points
    • Mainlines are sharper than alt lines and player props
  • Alt line - “alternate” spread or total for which you lay more juice or get longer odds
  • Player prop - betting on a specific player to record a certain amount of stats (passing yards, rebounds, shots on goal, etc.). Can be a very volatile market, tough to beat
  • Parlay - a series of 2+ wagers combined into ONE wager where all legs must win in order for the bet to be paid. If any of the legs lose, the entire ticket is a loser
    • Round Robin - sucker bet, don’t waste money on these. Not even worth explaining
    • SGP - “Same Game Parlay”, which is just a parlay including legs from the same game. Self explanatory. These are highly-juiced bets and in most cases are very -EV. Only bet these when there is a promo attached
    • OGP - “One Game Parlay” on BetMGM. Essentially the same as “SGP” on another book but you’ll see this mentioned every single day when I post my One Game Parlay Insurance picks
  • Kelly - a bet-sizing system used for optimal bankroll growth. See expanded answer below
    • Half Kelly - half of the optimal bet size. More conservative than Full Kelly
    • Quarter Kelly - ¼ of the optimal bet size. Extra conservative
  • Arb - betting on both sides of the same event to make guaranteed profit. These are rare and are an indicator that one side is +EV.
    • Arb-able - a bet that is “arb-able” is just one that can be arbed
  • Low-hold/no-hold - an opportunity to bet both sides of the same event and lose a small amount/break even. These are useful for clearing deposit matches and other promos that require a certain amount of playthrough
  • RTP - casino term meaning “Return to Player”, or the amount you can expect to get back from a casino game. Most often used with slots. I look for 97% or higher
    • High RTP games: Starmania, Bloodsuckers, Guns N’ Roses, Jimi Hendrix
  • Free bet - a common reward for completing promos. Best used on longer odds, see expanded explanation below
  • Variance - how often the expected outcome matches the actual outcome
  • Promo ban - after +EV betting for a while, some sportsbooks may “promo ban” you and exclude you from participating in promos. BetMGM and BetRivers are common ones who will promo ban users for winning too much money
  • NRFI - “No Run First Inning”, often denoted as “u0.5 runs” in the first inning of a baseball game
  • YRFI - “Yes Run First Inning”, often denoted as “o0.5 runs” in the first inning of a baseball game
  • Toronto Maple Leafs - banned
  • Hedging - this is a common tactic by parlay bettors (which you should avoid, btw) but is also highly relevant to promo/boost bettors. Many boosts can be hedged for guaranteed profit when there is only one leg left and it is tempting to do so. HEDGING IS -EV. If you are able to hedge a bet for a profit, that means the original wager is looking good. Making a -EV live wager only cuts into your profits in the long term. Unless you stand to win a life-changing amount of money, #TeamNoHedge is the way to go. Detailed example below
  • Middling - this is sort of like a hedge but gives you a window in which you can win both bets. For example, if Team A -3 is boosted to +110 on FanDuel and is +7 -110 on another, you have a very large “middle” opportunity
  • Bankroll - the amount of money that you have set aside ONLY for sports betting. You should be able to lose all of this money and not have it affect your life
  • Unit - 1% of your bankroll amount ^
  • Chalk - a “chalky” pick is just a heavy favorite, the opposite of an underdog
  • Whale lock - you’ll probably see me say this in a joking way. NOTHING IS A LOCK, don’t believe anyone who says they have a “can’t lose” bet lol


Frequently Asked Questions


Q: What is +EV betting?

A: +EV betting is using math based on proven, efficient markets to determine the true likelihood of a bet and compare it to the offered price.  Long story short, if a bet is being offered at a significantly better price than the market as a whole, that is a wager that is profitable in the long run.

Q: Should I have more than one sportsbook account? What if I only want to have one or two because it’s easier to keep track of?

A: I strongly advise you to open an account at every available sportsbook in your state.  Not only are the signup bonuses extremely lucrative, but having more options opens you up to more promos, boosts, and +EV bets. Remember, sportsbooks are competing for your business! Line shopping, boost/promo hunting, and certain VIP programs are a great way to remain profitable.

Q: What is a unit and how do I manage my bankroll properly?

A: A “unit” is usually 1% of your bankroll, which should be the total amount of money that you set aside for GAMBLING ONLY. This money should not affect your day-to-day life at all. As EVBetsIN once said: “you should be able to lose 30u in a week and not give much of a f***”

For me personally, my “bankroll” is $2,500 so my unit size is $25.  At any given time I likely have more money than that spread across my sportsbook accounts but I maintain a consistent virtual bankroll and unit size.  After you have proven to be profitable with your unit size and have enough money to sustain a bad run of variance, you can consider raising it.  Most people use a $10 unit size but it can vary quite a bit. 

PSA: NOBODY IS IMPRESSED by you having a bigger bankroll and you should not “unit shame” anyone who doesn’t bet as much as you do.

Q: What is the “optimal bet size” that you always talk about? What are all those numbers in your posts?

A: When calculating the EV of a bet, I try to include the following information:

  • Max bet
  • Win probability
  • Fair odds
  • Expected ROI (return-on-investment)
  • Optimal bet size (Full Kelly)

The win probability and fair odds are found by removing the “vig” (also referred to as “juice”) which is the amount that the sportsbook charges in order to take bets, kind of like a commission.  Expected ROI is the amount we can expect to profit over the long run (+9% on a $50 bet would be an expected profit of $4.50).

The optimal bet size is based on the Kelly Criterion for maximum bankroll growth. It is an AGGRESSIVE bet sizing strategy and as I’ve learned more and more about +EV betting, I’ve recognized that it is likely too aggressive. Many bettors, myself included, use “Half Kelly” or “Quarter Kelly” bet sizing to mitigate that risk.  In general I’ll use HK for mainline bets (spreads, ML, total) and QK for everything else.

Q: Do you make picks or is it all based on EV?

A: Some members make bets based on their personal feelings (as do I, but I rarely share them lol) but in the long run, the only way to win is to beat the books at their own game. We do this by finding spots where one sportsbook has an advantageous line when compared to others. If we do that enough times, we come out ahead.

An important thing to note is that almost 100% of my bets are based SOLELY on math. I do like to make some speculative bets from time to time but it is very rare.  This is a purely numbers-based strategy and has been proven to work over thousands of tracked bets.

Q: Why should I use free bets on longshots? Isn’t that just wasting them?

A: Free bets are different from normal bets in that when they win, the original “stake” is not returned to the bettor. For this reason, it’s advantageous to use these on longshot bets with higher payouts. I’ll demonstrate with a few examples below. Assume our free bet is $100 and the odds given are fair.

Scenario 1: +125 odds

  • With +125 odds, we can expect to win the bet 44.4% of the time
  • Formula for Expected Value (EV): P(Win)*(Potential Payout) - P(Loss)*(Stake)
  • EV = (.444)*(125) - (.556)(0)
  • EV = (55.5) - (0)
  • EV = 55.5
  • With an expected value of $55.50 from our original $100 free bet, this is a 55.5% “theoretical conversion” of our free bet. We can do MUCH better!

Scenario 2: +400 odds

  • With +400 odds, we can expect to win the bet 20% of the time
  • Formula for Expected Value (EV): P(Win)*(Potential Payout) - P(Loss)*(Stake)
  • EV = (.2)*(400) - (.8)(0)
  • EV = (80) - (0)
  • EV = 80
  • With an expected value of $80 from our original $100 free bet, this is an 80% “theoretical conversion” of our free bet. 

Scenario 3: +1500 odds

  • With +1500 odds, we can expect to win the bet 6.3% of the time
  • Formula for Expected Value (EV): P(Win)*(Potential Payout) - P(Loss)*(Stake)
  • EV = (.063)*(1500) - (.937)(0)
  • EV = (94.5) - (0)
  • EV = 94.5
  • With an expected value of $94.50 from our original $100 free bet, this is a 94.5% “theoretical conversion” of our free bet. 

Of the 3 scenarios above, Scenario 3 is the highest “EV”, but you are very unlikely to win the bet. I like to go for something like Scenario 2 where the expected value is solid, but there’s still a decent chance of winning the bet. It’s up to you how risky you want to be, but keep in mind that you should never settle for less than 70%.

Q: What is a “promo ban”? How do I avoid it?

A: Many books are extra cautious when it comes to players they allow to use their platform. Any indication that you are a profitable player could lead to them “promo banning” you, or excluding you from participating in promotions. These promo bans are often accompanied by low limits on bets and unfortunately, appear to be permanent. 

To avoid being promo banned, I recommend that you avoid “arbing” for large amounts of money, especially on obscure markets like player props.  Unfortunately, this is just part of the +EV betting game and you are very likely to be limited and/or promo banned by a couple books.

Q: Why is hedging bad?

A: Hedging a promo is bad because it reduces our expected value in the long run. If we can hedge a bet to guarantee a profit, then the original bet would have a high EV and the hedge bet is cutting into that.

*Hypothetical* example:

Lions to win boosted to +500

Max bet: $50

Win Probability: 22.2%

Fair odds: +350

Expected ROI: +33.3%

Optimal bet size: 6.7 units

We have a $50 bet on the Lions to win, with a potential profit of $250.

Now let’s say the Lions are up by 3 at halftime and the live odds are -110 on each side. Some folks might see this as a chance to hedge their bet and make a guaranteed profit. Sounds great on paper, but this is NOT a positive EV play! Let me break it down:

If the live odds are -110 on each side, the books are now saying that there’s a 50% chance that we win our bet. Our original bet was for +500 and now it’s a 50/50 chance!

Expected value of original bet based on current odds:

Lions ML +500

Win probability: 50%

Fair odds: +100

Expected ROI: +200% (!!)

Optimal bet size: 40 units

If you were offered that bet, you would hammer it. Now let’s see the EV of a live hedge bet on the opponent:

Lions Opponent ML

Win probability: 50%

Fair odds: +100

Expected ROI: -4.5%

Optimal bet size: -5 units

Despite the fact that betting on the Lions’ opponent would yield a “guaranteed” profit, all you’re really doing is paying the sportsbook some of your EV in order to reduce variance. In the long run, if you size your bets responsibly, you should not feel the need to hedge out of a profitable bet. Preserve your EV and join #TeamNoHedge!

Q: What do all these odds mean?

A: American odds are displayed as a comparison to a $100 wager. A favored outcome has “minus odds” and will have a minus sign in front. An underdog outcome is “plus odds” and will have a plus sign in front. 


Michigan State -7.5 (-120) -310 51.5 (-115)
Michigan +7.5 (+100) +250 51.5 (-105)

If you wanted to bet on Michigan State to WIN the game (smart), you would be laying -310 odds. In order to win $100, you would have to risk $310. So a bet on MSU ML would look like:

→ Risk $310 - To Win $100 - Total Payout $410

If for some reason you wanted to bet on Michigan to win the game, you would be taking +250 odds. For every $100 you risk, you would be paid $250. A bet on UM ML would look like:

→ Risk $100 - To Win $250 - Total Payout $350

To be continued!

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