Chalk

Chalk refers to the heavy favorite in a betting market. "Betting the chalk" means wagering on the obvious, popular choice—usually at odds that don't offer much value.

Origin of the Term

The term comes from old-school bookmaking when odds were written on chalkboards. Favorites got the most action, so their lines were constantly erased and rewritten—leaving more chalk residue than longshots.

Chalk Characteristics

Chalk bets typically feature:

The Chalk Problem

Betting chalk has structural issues:

Asymmetric risk/reward. Bet $300 to win $100 on a -300 favorite. One upset wipes out three wins.

Public overload. Squares love chalk. "The Patriots always win" thinking inflates favorite prices beyond fair value.

Juice extraction. Books shade chalk lines knowing recreational bettors will take favorites regardless. The vig hit is often worse on chalk.

When Chalk Has Value

Chalk isn't automatically bad—it's about price versus probability:

Fair value example:

• Your model says Team A wins 78% of the time
• Book offers Team A at -300 (implied 75%)
• This is +EV despite being chalk

Poor value example:

• Your model says Team A wins 72% of the time
• Book offers Team A at -350 (implied 77.8%)
• This is -EV, don't bet

The issue isn't favorites themselves—it's paying too much for them.

Chalk in Prediction Markets

On Kalshi and similar platforms, chalk manifests as contracts priced above 80¢. The same dynamics apply:

• High-probability events get overbet
• The remaining upside is small
• One wrong outcome hurts disproportionately

Our dashboards help identify when chalk is fairly priced versus overpriced by comparing market prices to historical probabilities.

Fading Chalk

Some bettors systematically bet against chalk—"fading the public." This can work when:

• Favorites are overvalued due to recency bias
• Underdogs are undervalued due to narrative
• The price doesn't reflect true probability

But blind contrarianism isn't a strategy. You need actual edge, not just the opposite of what squares do.

Related Terms

• Square — Recreational bettors who love chalk
• Dog — The opposite of chalk (underdog)
• Vig — Often worse on heavily bet chalk