Ever wondered why the odds change just before a race starts — or why your payout wasn’t what you expected? That’s the power of pool sizes and the pari-mutuel system. In horse racing, your bet goes into a shared pool with other players, not against a bookmaker. The size of that pool — and how it's distributed — plays a major role in how odds are calculated and what you win. Let’s break it down.
What is a betting pool in horse racing?
What is a betting pool in horse racing?
A betting pool is the total amount of money wagered on a particular type of bet — like Win, Place, Show, Exacta, or Pick 4. All bets of the same type go into their own pool, and the payout is divided among the winners after a small track takeout (commission).
Example: If $10,000 is bet in the Win pool, and $2,500 is on Horse 4, the odds and potential payout are calculated from that distribution.
How are odds calculated in pari-mutuel betting?
How are odds calculated in pari-mutuel betting?
Odds are not fixed — they change as more people place bets. Here’s how it works:
All bets go into a pool (e.g., Win bets).
The track deducts a takeout (usually 15-20%).
The remaining pool is split among winning bets.
Odds = (total money on all horses – takeout) / money on your horse
This is why odds fluctuate until post time and why final payouts are only known after the race starts.
Why do pool sizes matter to bettors?
Why do pool sizes matter to bettors?
Larger pools = more stable odds and bigger potential payouts
Smaller pools = odds move dramatically with fewer bets
Exotic pools (Trifecta, Superfecta, Pick 5) can offer huge payouts due to fewer winners
Pools also affect overlay opportunities — horses that offer better value than their real chance
At MyWinners, live odds and pool sizes are updated in real-time so you can track movements before placing your bet.
What should bettors know about odds and pools?
What should bettors know about odds and pools?
Odds shown pre-race are approximate, not final
Bet early and monitor pool size if you're chasing overlays
Late money can cause major shifts — especially on favourites
Final odds are locked at post time
Payouts vary by state based on local takeout rates and betting volume
💡 Did You Know? In 2023, a $0.50 Pick 5 ticket at a major US track paid over $125,000 — despite including multiple favourites. Why? The pool was huge, and few bettors hit all five legs.
Frequently Asked Questions
What does “takeout” mean in horse racing?
What does “takeout” mean in horse racing?
It’s the percentage deducted from the betting pool by the track or regulator — typically 15–20%. The rest goes to the winners.
Why do odds change so much before the race starts?
Why do odds change so much before the race starts?
Because it’s a pool-based system. The more people who bet on a horse, the lower the odds. Big bets close to post time can shift everything.
Can I see pool sizes on MyWinners?
Can I see pool sizes on MyWinners?
Yes — MyWinners.com shows live updates of pool sizes, odds, and “Will Pays” to help you make informed bets.
What are overlays and how do I spot them?
What are overlays and how do I spot them?
An overlay is a horse offering higher odds than its actual winning chance. If you think a horse is 4-1 but it’s paying 8-1, that’s value — often found in unbalanced pools.
Are bigger pools always better for payouts?
Are bigger pools always better for payouts?
Generally, yes — especially on exotic bets. More money in the pool = more to win, but also more competition and betting activity.