Expected Value Calculator

The most important calculation in gambling. Determine if a bet will be profitable long-term by measuring the gap between the sportsbook's odds and the true probability.

Wes Frank
Wes FrankFounder, EdgeSlip Analytics
Updated Dec 25, 2025
Fact Checked

EV Calculator

Find Your Edge

1%50%99%
Where to get True Probability? The most accurate way is to find a sharp bookmaker (like Pinnacle), remove the vig using our No-Vig Calculator, and use that percentage here.

Value Analysis

Expected Value
+$10.00
EXCELLENT (+10.00%)
Implied Win %
45.45%

Break Even Point

Your Win %
50.00%

Your Projection

Want automated EV? Calculating EV manually is slow. Our Live Feed scans 4,000+ odds per minute to find +EV bets instantly.

Open +EV Dashboard

What is this tool?

Expected Value (EV) is a calculation that measures the average amount of money a bettor can expect to win or lose per bet if the same wager were placed an infinite number of times. In sports betting, finding Positive Expected Value (+EV) is the only mathematical way to be profitable in the long run. If a bet has +EV, it means the potential payout is higher than the risk implies.

How to use it

First, enter your 'Wager Amount'. Next, enter the 'Sportsbook Odds' (the price the book is offering you). Finally, enter the 'True Probability' (the actual percentage chance the bet wins). The calculator will output the EV in dollars and percentage. You should only place bets where the EV is positive (> 0%).

The Concept: The Coin Flip

To understand EV, imagine a fair coin flip (50% Heads, 50% Tails).

Fair Odds (+100)

You bet $100 on Heads to win $100.

  • 50% of time: Win $100
  • 50% of time: Lose $100
  • EV = $0.00 (Neutral)
Value Odds (+120)

You bet $100 on Heads to win $120.

  • 50% of time: Win $120
  • 50% of time: Lose $100
  • EV = +$10.00 (Positive)

The EV Formula

The formula for Expected Value combines the probability of winning with the potential payout, and subtracts the probability of losing multiplied by the stake.

EV = (%Win × Profit) - (%Loss × Stake)

For example, if you bet $100 on a team with decimal odds of 2.50 (+150 American) and you believe they have a 45% chance to win:

  • Potential Profit = $150
  • Win Probability = 0.45
  • Loss Probability = 0.55
  • Calculation: (0.45 × $150) - (0.55 × $100)
  • $67.50 - $55.00 = +$12.50 EV

Win Rate vs. Expected Value

One of the biggest misconceptions in sports betting is that you need a high win rate to be profitable. This is false. You can win 60% of your bets and lose money (if you only bet huge favorites), and you can win 40% of your bets and make a fortune (if you bet profitable underdogs).

EV is the great equalizer. It accounts for both the probability of winning AND the payout. A bet with a 35% chance of winning can have a higher +EV than a bet with an 80% chance of winning if the odds are mispriced enough. Professional bettors don't chase wins; they chase value.

Where to find "True Probability"

The hardest part of the equation is knowing the "True Probability" (Win %). You cannot simply use your gut feeling. There are two primary methods professional bettors use to determine this number:

1. Market Origination (De-vigging)

Sharp bookmakers (like Pinnacle or Circa) are extremely efficient markets. They accept high limits and move lines based on smart money. By taking their odds and removing the "vig" (juice) using a No-Vig Calculator, you get the most accurate, crowd-sourced probability available in the world. If a soft book (like FanDuel) offers better odds than this "True Price," you have an edge.

2. Statistical Modeling

This involves creating your own power ratings (e.g. Elo ratings, xG models in soccer, or player projection models in the NBA). If your model determines that a team actually has a 55% chance to win, but the sportsbook's odds imply they only have a 50% chance, you have identified a discrepancy to exploit.

The Law of Large Numbers

Expected Value is a theoretical number. If you place one +EV bet, you will either win (make profit) or lose (lose stake). You will never actually win the "Expected Value" on a single event.

EV relies on volume. It is based on the Law of Large Numbers, which states that as the number of trials increases, the actual results will converge on the expected results. If you consistently bet with a +5% edge, you might lose money over 10 bets or even 50 bets due to variance. But over 1,000 bets, it is mathematically nearly impossible to lose money. This is why bankroll management and the Kelly Criterion are vital companions to EV betting.

Frequently Asked Questions

What is a good EV percentage?▼
Anything above 0% is technically profitable. However, considering variance, most professional bettors look for an edge of +3% to +5% or higher. In niche markets like Player Props, you can often find +10% EV or more.
Does +EV mean I will win the bet?▼
No. +EV simply means that the bet is a good investment mathematically. You can (and will) lose many +EV bets. For example, a bet with a 10% edge might still only have a 40% chance of winning. Expected Value plays out over hundreds or thousands of bets (The Law of Large Numbers).
How do I calculate EV with American Odds?▼
First, convert American Odds to Decimal Odds. For positive odds (e.g. +150), divide by 100 and add 1 (1.50 + 1 = 2.50). For negative odds (e.g. -110), divide 100 by the odds and add 1. Then use the formula: (Probability x (Decimal - 1)) - ((1 - Probability) x 1).
What is the difference between EV and ROI?▼
Expected Value (EV) is predictive—it tells you what you expect to make before the game starts. Return on Investment (ROI) is historical—it measures what you actually made after the bets are graded. Ideally, your long-term ROI should match your average EV.
Can I use the Kelly Criterion with this?▼
Yes! In fact, you should. Once you know the EV and the True Probability, you should plug those numbers into a Kelly Criterion Calculator to determine exactly how much of your bankroll to wager to maximize growth and minimize risk.
Get Started Today

Ready to find your Edge?

Join thousands of smart bettors who have stopped guessing and started calculating. Access institutional-grade tools for the price of a standard wager.

Start Free Trial Explore Features
No credit card requiredCancel Anytime