An alternate spread is when you bet on a line that is different from the official line. For example, say the Celtics are on the road facing the Heat in the NBA and the oddsmakers open the Heat as a -2.5 favorite.
That means that the juice would be (-110) on each side of the bet, whether you are taking Celtics +2.5 or Heat -2.5. Now, say you are confident that the Heat will not only cover the spread, but you think the Heat will win by double digits.
You can then bet on the alternate spread of Heat -9.5. Why would anyone lay that many more points?
Well, the payout is much higher if you take that wager. Like I said earlier, the juice on Heat -2.5 would be (-110), but if you were to take Heat -9.5, then you would probably get odds somewhere around (+250).
So if you are confident enough that the Heat not only covers the official line but also this alternate spread, then you can bet $100 to win $250 on Heat -9.5 instead of betting $110 to win $100 on Heat -2.5. Alternate spreads also work the other way if you wish to lay more juice.
Following this same example, let’s say you think that there is no way the Celtics lose this game by double digits. Then, you can wager on the Celtics alternate spread of +9.5.
However, you will need to lay somewhere around (-330) in juice as this scenario is much more probable. A better who is not comfortable betting $110 to win $100 on Celtics +2.5 can bet $330 to win $100 on Celtics +9.5.
There are alternate spreads available in pretty much every single sport you can wager on. While in the NBA the odds do not change dramatically for each point as there are so many points scored, the odds fluctuate much more on alternate spreads when betting on sports such as hockey and professional football.