Value & Strategy Tools
Arbitrage Calculator
Split a stake across two sportsbooks on opposite sides of a game to lock in a guaranteed profit whichever way it lands, in dollars.
Betting ROI Calculator
Work out your betting return on investment - profit as a percentage of everything you staked - to measure how well your bankroll is performing, in dollars.
Bookmaker Margin Calculator
Compare how much margin different sportsbooks build into the same market, from their American odds, to find the sharpest prices.
Buying Half Points Calculator
See what buying a half point costs - how much profit you give up when you move a spread or total in your favor by moving the price, in dollars.
Closing Line Value (CLV) Calculator
Measure how much you beat the closing line by, comparing the American odds you took with the price at kickoff, as a percentage.
Dutching Calculator
Split a stake across two or more selections in one market so every winner returns the same amount, worked from American odds in dollars.
Expected Value (EV) Calculator
Work out the expected value of a bet from your true win probability and the American odds, to see if a price is a long-run winner.
Hold Percentage Calculator
Measure a sportsbook's hold - the margin baked into a market - by adding the implied probabilities of every outcome from their American odds.
Kelly Criterion Calculator
Find the mathematically optimal stake for a bet from your edge and the American odds, sized as a percentage of your bankroll.
Strike Rate Calculator
Find the break-even strike rate any price demands - the share of bets you must win at given American odds just to stay even, as a percentage.
Surebet Calculator
Check whether two odds form a surebet and get the exact stake on each side to guarantee the same profit whichever result lands, in dollars.
Win-Loss Record Calculator
Turn a win-loss record into a win percentage and a net profit in units, and see the break-even rate you need at -110, in dollars.
Winning & Losing Streak Calculator
Work out the probability of a run of wins or losses from your win rate, so you can size a bankroll that survives the cold spells, in dollars.
The tools that separate strategic bettors from the rest — they answer whether a bet is worth placing and how much to stake.
Core ideas
- Expected value (EV): the average profit if you placed a bet many times. +EV wins long term, -EV loses.
- Kelly criterion: once a bet is +EV, Kelly sets the optimal stake — too little leaves profit, too much risks ruin.
- Margin (hold/vig): the book’s built-in edge; lower margins are easier to beat.
- Arbitrage: when books disagree enough, cover all outcomes for a locked profit.
A simple workflow: check the margin, test for +EV, size with Kelly, then track ROI and strike rate.
Frequently Asked Questions
What is value betting?
Value betting means placing bets where the probability of an outcome is higher than what the bookmaker’s odds imply. If you estimate a team has a 50% chance of winning but the odds imply only a 40% chance, that is a value bet. Over time, consistently finding and betting on value leads to long-term profit, regardless of individual wins or losses.
What is expected value (EV) in betting?
Expected value is the average amount you can expect to win or lose per bet over time. It is calculated as: EV = (Probability of Winning × Profit) − (Probability of Losing × Stake). A positive EV (+EV) bet is profitable long term, while a negative EV (−EV) bet will lose money over time. Professional bettors focus exclusively on placing +EV bets.
What is the Kelly Criterion?
The Kelly Criterion is a mathematical formula for calculating the optimal bet size based on your edge (the difference between true probability and implied probability). The formula is: Kelly Stake % = (bp − q) / b, where b is the decimal odds minus 1, p is your estimated true probability, and q is 1 − p. It maximizes long-term growth while minimizing the risk of ruin. Many bettors use a fractional Kelly (e.g. 25-50% of the full Kelly stake) for added safety.
What is the bookmaker's hold (vig)?
The hold, also called vig (vigorish), juice, or overround, is the bookmaker’s built-in profit margin. It is the difference between the true probabilities and the implied probabilities from the odds. For example, if a fair 50/50 market is priced at 1.91/1.91 instead of 2.00/2.00, the hold is approximately 4.8%. Lower hold markets offer better value for bettors.
What is arbitrage betting?
Arbitrage betting (arbing) involves placing bets on all possible outcomes of an event across different bookmakers at odds that guarantee a profit regardless of the result. This is possible when bookmakers disagree on the probabilities, creating a combined implied probability below 100%. Arbs are rare and typically small (1-5% profit), and bookmakers may limit accounts that consistently exploit them.
How do I calculate my required strike rate?
Your required strike rate is the minimum win percentage needed to break even at given odds. The formula is: Required Strike Rate = 1 / Decimal Odds × 100%. At odds of 2.00, you need to win 50% of bets to break even. At 3.00, you need 33.3%. If your actual strike rate exceeds the required rate, you are betting profitably. Our calculators help you track this across different odds levels.
How do I calculate my betting ROI?
ROI (Return on Investment) measures your overall profitability as a percentage. The formula is: ROI = (Total Profit / Total Staked) × 100%. For example, if you have staked $10,000 total and your profit is $500, your ROI is 5%. Professional bettors typically achieve ROI between 2% and 10% — anything above that consistently is exceptional.
Is value betting better than arbitrage betting?
Both are valid strategies. Arbitrage offers guaranteed profit per event but smaller margins, requires accounts at many bookmakers, and carries high risk of account restrictions. Value betting offers larger long-term profits but involves variance — you will have losing streaks even while making +EV bets. Value betting is generally more sustainable because it looks like normal betting to bookmakers and is harder to detect.