Kalshi vs. the Sportsbooks: NFL Game Prices, Week by Week

A sportsbook prices the Buffalo Bills to beat the Detroit Lions at one number. Kalshi prices the same outcome as a contract that pays a dollar if the Bills win. The two rarely land in exactly the same place, and the question a bettor actually has is which one is cheaper right now, not which one is more likely to be right. This page runs that comparison for Week 2, for every game with both a book line and a Kalshi quote, 16 of them, put on the same cents-on-the-dollar scale so a bettor can read them side by side.

The average gap between the two venues this week runs 0.9 cents, small most of the time and occasionally not. After Kalshi’s fee is added into the math, 9 of 32 sides price cheaper on the exchange than at the books. The table below carries that comparison for every game on the slate, and past weeks sit underneath it so the same check can be run kickoff after kickoff instead of once.

Week 8: Kalshi vs. the sportsbooks

What The Table Actually Compares

The book number on this page comes from the Odds API’s lines from 28 books, Pinnacle where it prices the game and a consensus otherwise, then devigged. Devigging strips out the cut a sportsbook keeps on both sides of a line, so what’s left is a fair probability rather than the price a bettor would actually be charged to bet it. That fair number, not the raw line, is what sits on the books’ side of the comparison.

Kalshi’s side is its mid, the midpoint between the best bid and best ask on that team’s Yes contract. Both numbers are expressed the same way, cents on the dollar, so a book price of 68 cents and a Kalshi mid of 68.5 cents mean roughly the same thing: two venues each putting close to a two-in-three chance on the same team winning.

Every game carries a moneyline row, and a spread row and a total row when the books’ number for that market matches how Kalshi prices it, in half-point contracts such as wins by more than a set margin or goes over a set total. A book line that lands on a whole number doesn’t have a matching Kalshi contract, so that row is left out of the comparison rather than forced to fit.

The point of putting these three bet types on one page is that most bettors are pricing spreads and totals, not just moneylines, and the gap between the two venues can behave differently across all three. Reading them together, on the same scale, is the only way to see where the disagreement is actually concentrated on a given week.

How A Kalshi Price Actually Forms

Kalshi runs two markets per game, one for each team. A Yes contract on a team pays a dollar if that team wins and nothing if it loses, so a contract trading around 68 cents is the market saying that team wins about 68% of the time, no more complicated than that.

Like any order book, there’s a bid, what a buyer is currently willing to pay, and an ask, what a seller currently wants, and the mid sits at the midpoint between them. Traders who post those resting orders are makers. Traders who accept one of those orders and complete the trade are takers, and it’s the taker who pays Kalshi’s fee.

None of that price comes from a bookmaker’s opinion of the matchup. It comes from what traders on both sides of the contract are actually willing to buy and sell for at that moment, which is order flow rather than a house line. That’s also why a heavily traded game’s price tends to sit close to where the books have it, while a game nobody has traded much yet can drift further away with no correction in sight until volume shows up.

The Fee, And Why The Mid Isn’t What Anyone Pays

Kalshi charges its taker about 7% of expected profit on a contract, not a flat percentage of the trade itself. That structure makes the fee largest near the middle of the range and smaller toward either end of it: $1.75 on 100 contracts at 50 cents, compared with $1.12 on 100 contracts at 80 cents on a contract trading closer to 80 cents.

That fee is exactly why the mid is not a price anyone actually pays to get into a position. A buyer pays the ask, plus the fee on top of it, and that combined number, ask plus fee, is the one that belongs in a comparison against a sportsbook’s price, since the sportsbook’s own number already has its vig built in.

The table’s cheaper-after-fees column runs precisely that comparison, Kalshi’s ask plus fee against the books’ price for the same side of the same bet. Reading the mid against the books’ fair number is a fine way to spot where the two venues disagree, but it’s not the number to check right before placing money, and treating it as one is the most common way this comparison gets misread.

Why The Exchange And The Books Land On Different Numbers

A sportsbook sets one number and charges vig on both sides of it, then shades that number toward the action it wants and away from the action it’s trying to limit. Its betting limits cap how much any single bettor can put on a game, and that cap is part of how the book manages its own risk on a line it doesn’t want to move too far.

An exchange doesn’t have a house side at all. The other party to every Kalshi contract is another trader, not a bookmaker, so the only real costs are the bid-ask spread and the fee, and what caps the size of a trade is available liquidity rather than a limit set by management. Books also tend to see injury and lineup news first, since they employ people whose job is to price it the moment it breaks, while the exchange only moves once a trader acts on that same news.

This week that disagreement shows up widest in Philadelphia Eagles at Tennessee Titans, where the Eagles trades 2.3 cents higher on Kalshi than the books’ fair price has it, 76.5 cents against 74.2 cents.

Gaps like that tend to narrow as kickoff gets closer, since a trader who spots a Kalshi price sitting away from a sportsbook line has a direct incentive to trade against it until the two move back together. Early in the week, before much volume has come through, the exchange and the books have the most room to sit apart.

When The Exchange Wins, And When It Doesn’t

The only test that decides this is whether Kalshi’s ask plus fee comes in below the books’ price for that same side. The table runs that test for every side on the board, which means the cheaper-after-fees column, not the size of the gap in the mid, is what actually decides where the better price sits on a given morning.

This week, 9 of 32 sides price cheaper on Kalshi after the fee, and 23 price cheaper at the books, which is the more common outcome across a typical slate.

Underdogs show up cheaper on the exchange more often than favorites do, but that’s a tendency, not a rule to bet blind, and it reverses often enough that it shouldn’t replace actually reading the table. A wide gap between the two mids without a matching edge in the ask-plus-fee column just means the two venues see the game differently, not that either side of it is a good bet on its own.

Reading Volume And The Bid-Ask Spread Before Trusting A Price

Volume is the number of contracts that have actually changed hands on a market, each worth at most a dollar once the game settles. Open interest is how many of those contracts are still open rather than already closed out. A large volume number paired with a tight bid-ask spread points to a real, two-sided market. A large volume number paired with a wide spread usually means one side has done nearly all the trading, and the price hasn’t been tested from the other direction.

This week’s busiest market is Detroit Lions at Buffalo Bills, with 2,219,847 contracts traded so far. The widest bid-ask spread on the board belongs to Indianapolis Colts at Kansas City Chiefs, at 2 cents.

A thin market’s mid can look identical to a heavily traded one’s on the page, but it carries far less information behind it, since a handful of trades can push it around and its ask might sit well away from where the mid appears to be. Checking volume and spread before treating any Kalshi price as meaningful is worth doing on any game that hasn’t drawn much action yet, and it matters more the earlier in the week the check is being made.

The Weekly Routine This Page Is Built For

The table works best as a morning check rather than a one-time read. Scan the gap column first for the sides where Kalshi and the books disagree the most, then move to the cheaper-after-fees column for whichever side is actually under consideration, then check volume and the bid-ask spread before trusting a market that hasn’t traded much yet that day.

Past weeks sit below the current table, closed out with the game’s result attached, and they exist to answer a specific question: did that week’s gaps actually close by kickoff, and which venue’s price ended up closer to right. That running record is what turns a single morning’s snapshot into something worth returning to.

A few limits are worth keeping in mind while using it. The books’ number reflects one consensus line built from many sportsbooks, not the price at every single one of them individually. Kalshi’s side of the table is a morning snapshot that moves throughout the day as more contracts trade. None of it is a prediction about who wins the game, only a comparison of what each venue is charging right now, and Kalshi’s sports contracts aren’t offered in every state, so availability should be checked before any of this becomes actionable.