How much are Kalshi trading fees?

Kalshi's taker fee is 0.07 times contracts times price times one minus price, rounded up to the next cent. The maker fee uses 0.0175 with the same formula on markets that carry one. Fees are highest near 50 cents and decline toward the extremes. Winning contracts settle at $1.00 with no settlement fee.

Do I pay prediction market fees twice if I sell before settlement?

Yes. Fees apply on entry and again on exit. If you plan to trade out rather than hold to settlement, expect roughly double the fee, though actual exit cost depends on the price at that time.

Kalshi vs Sportsbook Odds Converter

How prediction market pricing works

On Kalshi, Polymarket, or Robinhood Predictions you're not taking a price from a sportsbook — you're buying a contract from another trader. Each contract settles at $1.00 if you're right and $0.00 if you're wrong.

So the price is the probability. A contract trading at 55¢ means the market collectively thinks there's a 55% chance. Pay 55¢ to win $1.00 and you're risking 55 to make 45 — which converts to -122 in American odds.

That's the number people quote. It's also not the number you get.

Why 55¢ isn't really -122

Every one of these platforms charges a trading fee on top of the contract price. It isn't built into the quote the way a sportsbook's vig is built into -110. You pay 55¢ for the contract and then you pay the fee separately.

The shape of the fee is the important bit. All three platforms use some version of rate × contracts × price × (1 − price).

That price × (1 − price) term peaks at 50¢ and shrinks toward the extremes. So fees bite hardest on close-to-even markets — exactly where most sports betting happens — and barely register on heavy favorites and longshots.

At 50¢ on Kalshi, the taker fee runs about 1.75¢ per contract. That doesn't sound like much. It moves your effective price from 50¢ to 51.75¢, which turns +100 into roughly -107. You just gave up 7 points before the event started.

What the fee costs at different prices

Kalshi taker fee, 100 contracts, showing what the screen says versus what you actually get:

Contract price	Screen odds	Real odds	Cost
20¢	+400	~+357	43 pts
35¢	+186	~+167	19 pts
50¢	+100	~-107	~7 pts
65¢	-186	~-208	22 pts
80¢	-400	~-459	59 pts

Run your own numbers in the tool above — order size changes things, because the rounding-up-to-the-next-cent rule hits small orders disproportionately hard. A single contract can pay several times the effective rate of a 500-contract order.

Does the exchange actually beat your sportsbook?

That's what the Beat the Book section answers. Enter the sportsbook price on the same side and it returns the maximum contract price at which the exchange still wins after fees.

If your book has a side at -110, you need roughly 52.38% to break even. The tool works backwards through the fee formula to find the highest contract price whose all-in cost still lands under that number. Pay at or below it and the exchange is the better venue. Pay above and take the book.

This is genuinely useful because the naive comparison — "55¢ is -122, my book has -110, so the book wins" — happens to be right here but is wrong often enough to cost money. At wider prices the fee-adjusted answer regularly flips the naive one.

Where prediction markets genuinely win

Maker orders can be free. A resting limit order on Polymarket pays no fee at all, and Kalshi's maker rate is a quarter of its taker rate. If you're patient enough to post rather than take, the math changes completely.
Nobody gets limited for winning. This is the real structural advantage. Beat a sportsbook consistently and your max bet shrinks to pocket change. Exchanges don't care — you're trading against other users, not the house.
The extremes are cheap. Because the fee shrinks toward 0¢ and 100¢, heavy favorites and big longshots carry far less friction than a sportsbook's equivalent juice.

Where they lose

Small orders get hammered by the round-up-to-the-cent rule.
Liquidity is thinner. A screen price you can't get size at isn't really a price.
Fewer markets. Sides and totals on major games, mostly. Not the prop depth a sportsbook offers.
Availability varies by state — some jurisdictions restrict sports event contracts specifically while allowing other categories. Check what's actually tradeable where you are.

Common questions

How do you convert a prediction market price to American odds?

Divide 1 by the contract price in dollars to get decimal odds, then convert. A 55¢ contract is 1 ÷ 0.55 = 1.818 decimal, which is -122 American. That ignores trading fees — adding the fee to your cost per contract before converting gives the odds you actually receive.

How much are Kalshi's trading fees?

Kalshi's taker fee is 0.07 × contracts × price × (1 − price), rounded up to the next cent. The maker fee is 0.0175 with the same formula, applied only on markets that carry one. Because of the price × (1 − price) term, fees are highest near 50¢ and decline toward the extremes. Winning contracts settle at $1.00 with no settlement fee.

Is Kalshi or Polymarket cheaper than a sportsbook?

It depends on the price and the order type. Maker orders on Polymarket carry no fee and often beat a sportsbook clearly. Taker orders near 50¢ can end up close to standard -110 pricing once fees are included. The comparison tool above resolves it for any specific price.

Why are prediction market fees highest near 50 cents?

All three platforms use a formula containing price × (1 − price), which is largest at 0.50 and approaches zero at either extreme. The design charges most where uncertainty is greatest, which means close-to-even sports markets carry the heaviest fee load.

Do I pay the fee twice if I sell before settlement?

Yes. Fees apply on entry and again on exit. If you plan to trade out rather than hold to settlement, tick the round-trip box above — it roughly doubles the fee, though your actual exit cost depends on the price at that time.

Can prediction markets limit or ban winning traders?

Not the way sportsbooks do. On an exchange you trade against other participants rather than the house, so consistent winners aren't a liability to the platform. This is the clearest structural advantage exchanges hold over traditional sportsbooks.

Prediction Market Converter

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