Kalshi fee calculator

The formula

A Kalshi trade fee depends on the price and the number of contracts. With C the number of contracts, P the price in dollars and M the series' fee multiplier:

• Taker (an order that fills at once against a resting price): fee = round up(M × 0.07 × C × P × (1 − P)). M is 1 on most series.
• Maker (a resting order that someone else fills later): fee = round up(M × 0.0175 × C × P × (1 − P)), charged only where the series lists maker fees. Elsewhere M is 0 for makers and the fee is nothing.

P × (1 − P) is largest at 50¢, so the fee peaks there: 1.75¢ a contract before rounding for a taker. It shrinks toward both ends of the price range, and it is the same at P as at 1 − P. The fees article in Kalshi's help center links the full schedule.

Fee by price

Taker fees at multiplier 1, and the maker fee where a series charges one, after rounding, each as one fill:

A taker buying one contract at a whole-cent price pays at least 1¢, because the cost plus the fee rounds up to a whole cent. At 100 contracts the rounding matters less and the curve shows: $1.75 at 50¢, 34¢ at 5¢ or 95¢.

When makers pay

A maker fee is charged only when a resting order is filled, and only on series that list maker fees: Kalshi's API marks them with a fee type that names maker fees, such as “quadratic_with_maker_fees”, where the maker coefficient is 0.0175. On a series with the plain “quadratic” type, makers pay nothing. Combo markets (fee type “quadratic_with_combo_maker_fees”) charge makers at twice that rate; the calculator does not price them and says so.

Multipliers differ by series, and Kalshi can change them. When we read Kalshi's API on October 6, 2026, the 15-minute bitcoin series (KXBTC15M) had type quadratic at multiplier 1, so takers paid the standard fee and makers nothing; the Fed decision series (KXFED) charged makers too, at multiplier 1; and the baseball game series (KXMLBGAME) charged both at multiplier 0.5. Enter a ticker above for today's setting.

How rounding works

Rounding happens per fill, as Kalshi's rounding rules set out. The formula fee is rounded up to a millionth of a dollar. Then the fill's cost plus the fee is rounded up to a whole cent (a sale's proceeds round down), and the difference counts as fee. So one contract bought at 95¢ has a formula fee of 0.3325¢ and costs 96¢ in all. Kalshi's direct members round to a hundredth of a cent instead; the calculator uses the whole cent, which applies to everyone else.

When an order fills in several pieces, Kalshi tracks that rounding across the order and refunds it a cent at a time, so the order's total fee comes close to what one fill of the same size would pay. The calculator prices the order as one fill.

Breakeven win rate

A contract pays $1 if it wins. If you pay an all-in cost of c a contract, fee included, and hold it to settlement, you break even when you win a share c ÷ $1 of the time: at 52¢ all in, 52%. The calculator rounds the cost a contract and the breakeven up, never down. Selling before settlement pays a fee on the sale too, so a trade you close early pays two fees.

Questions

Does Kalshi charge makers?

Only on series that list maker fees. Kalshi's fee schedule sets the maker multiplier to 0 unless a series is listed with one, so on most series a resting order that is filled later pays nothing. On series with the fee type quadratic_with_maker_fees, makers pay at a coefficient of 0.0175, a quarter of the taker's 0.07. Kalshi's combo markets have a maker fee of their own, which this calculator does not price. Enter a ticker above to see what a series charges today.

Is the fee charged per contract or per order?

Per fill. The formula takes the number of contracts in the fill, and the rounding is applied to the fill as a whole, which is why one contract at 50¢ pays 2¢ while 100 contracts pay $1.75, not $2.

Does canceling an order cost anything?

No. A resting order pays a fee only if and when it is filled. Canceling it costs nothing.

Does this work for selling, or for NO contracts?

Buying NO at a price is priced the same way as buying YES at that price, so enter the NO price. The calculator prices a buy. A sale pays the same formula fee, but its proceeds round down to the cent instead of the cost rounding up.

Why can a ticker's answer differ from the standard one?

Each series carries its own fee type and multiplier, an event can override its series, and a market can carry a fee waiver. With a ticker, the calculator reads all three from Kalshi's public API, cached for up to an hour.

Does Windmill's paper trading charge these fees?

Yes. This calculator runs the same fee code our paper trading engine books every paper fill with.