How the +EV Bets FairLine Works
A deep dive into our proprietary vig-free probability benchmark
6 min read
The Problem with Sportsbook Odds
Every sportsbook line includes a built-in profit margin called the vig (or juice). When a fair coin flip is priced at -110 on both sides, the book collects ~4.5% regardless of the outcome. This vig means the odds you see never reflect the true probability of an event.
The FairLine was built to solve this. By stripping the vig and synthesizing signals from across the betting market, it estimates what the odds should be — a vig-free probability benchmark.
How the FairLine Estimates Fair Probability
The FairLine isn't a single prediction model. It's a synthesis engine that combines multiple market signals into a single, honest probability estimate:
1. Aggregate Market Odds
We continuously ingest odds from major US sportsbooks across all supported markets: moneyline, spread, and totals for NFL, NBA, MLB, NHL, NCAAF, and NCAAB.
2. Strip the Vig
The algorithm removes each book's built-in margin to reveal the underlying implied probability. This vig-free baseline is the starting point for fair odds estimation.
3. Synthesize & Weight
Sharp market signals are weighted more heavily. The FairLine blends these signals into a single probability estimate that's market-aware and conservative by design.
From Fair Probability to +EV Opportunities
Once the FairLine establishes fair probability for an event, identifying +EV bets is straightforward: compare the FairLine to each sportsbook's current odds.
FairLine probability: Bills win = 58%
DraftKings line: Bills -135 (implied 57.4%)
FanDuel line: Bills -125 (implied 55.6%)
FanDuel is +EV: Book implies 55.6%, FairLine says 58% → +2.4% EV
In this example, FanDuel's line is mispriced relative to the broader market consensus. A bettor taking Bills -125 on FanDuel has a mathematical edge — the definition of a +EV bet.
Why the FairLine Is Conservative by Design
Many betting tools inflate edges to generate more picks. The FairLine takes the opposite approach: it's calibrated to be conservative, which means:
Fewer opportunities, higher quality — We'd rather surface 5 genuine +EV bets than 50 borderline ones.
No model overconfidence — By anchoring to market consensus rather than a single predictive model, the FairLine avoids the false precision that plagues many quantitative approaches.
Built-in skepticism — If only one book has a significantly different line, the FairLine doesn't automatically call it +EV. The mispricing needs to be meaningful relative to market uncertainty.
Frequently Asked Questions
What makes the FairLine different from other betting models?
Most betting models try to predict winners. The FairLine takes a different approach: it estimates fair probability by synthesizing market-wide signals, then identifies where individual sportsbooks deviate from that baseline. This market-aware methodology is inherently more conservative and produces fewer, but more reliable, +EV opportunities.
How often is the FairLine updated?
The FairLine updates continuously as new odds data flows in from sportsbooks. Premium subscribers see odds updated as often as every 5 minutes near game time, ensuring they can act on opportunities before lines correct.
Can I see the math behind each +EV recommendation?
Yes. Every opportunity on +EV Bets displays the FairLine probability, the sportsbook's implied probability, and the resulting EV percentage. Full transparency is a core principle of the platform.