Everything bundle
The playbook, the journal and all four 2027 event guides.
Parlay & prediction market calculator
Your parlay is overpriced. Find out by how much.
Type in your legs and the quote. In ten seconds you see what you're really paying for the bundle.
Free · No signup · Works for sports, CPI, the Fed, elections, anything that settles yes or no
Combo tax meterLive
+15%markup over the legs
$13 of every $100 you put on this combo is markup.
Legs treated as unrelated. The full calculator handles related legs and fees.
22%of one exchange's volume was combos by April 2026, up from under 2% in October 2025
$116.8Mlost by customers on combos in 2026
$35M+in exchange fees on combos, 2026 through April
Source: Sportico analysis of public Dune data, 2026.
The guides
Know the price before you take it
The Hedging Playbook
Cover your cost, lock the result, or cap the loss, sized before you buy.
$19
Buy for $19
Trade Journal
See where you actually make and lose money. Excel and Google Sheets.
$29
Buy for $29
The Combo Tax
The 10-page guide to what a combo really costs.
Free
Send me the free guide
Event guides, $12 each
Ready before the games that matter
Free tools
Six calculators. No signup.
Combo price
Markup, break-even and expected value.
Check a combo →Hedge
Both outcomes for any hedge size.
Plan a hedge →Odds converter
Cents to odds and back.
Convert a price →Fee calculator
The fee, your all-in cost and break-even.
Price an order →Expected value
Is the price worth it at your odds?
Run the EV →Implied probability
Add up a field and strip the markup.
Read a field →New to this? How prediction markets work, in one page → · Glossary →
Anything can be a contract. Same math.
Home team winsCore CPI 0.3%+Fed holdsCandidate wins the stateCity high above 90°FFilm wins best picture
Every one pays $1 if it settles yes. What you can trade, and how to read any contract →
Prediction markets, quickly
What is a prediction market?
A prediction market lists contracts on real outcomes, such as a game, a CPI release, a Fed decision, an election or the weather. Each contract pays $1 if it settles yes and $0 if it doesn't, so its price in cents reads roughly as the market's probability.
How do prediction market prices work?
A price of 62¢ means the market puts the outcome near 62%. You pay the price plus a fee, so your break-even is a little above it. The yes and no sides add up to about 100¢.
What is a parlay or combo on a prediction market?
A combo, called a parlay at a sportsbook, is one contract that pays $1 only if every leg settles yes. Its fair reference price is the legs multiplied together. The quote is usually higher, and the difference is the markup.
How do I know if my parlay is overpriced?
Multiply the leg prices as probabilities and compare the result with the quote. Three legs at 62¢, 58¢ and 70¢ multiply to about 25.2¢, so a 29¢ quote carries about a 15% markup. The meter above does this as you type.
Can I hedge a prediction market position?
Yes. Buying the opposite side of a contract limits what you can lose. Hold the same number of contracts on both sides and you get the same result whichever way it settles, as long as the two prices add up to less than 100¢.
Is this financial advice?
No. These tools and guides explain how prices, fees and hedges work. They don't predict outcomes or recommend trades, and event contracts can lose 100% of what you pay.