Calculator

Kalshi Fee Calculator

About this calculator

The price on the exchange is not the price you pay. Here is the fee, and where it moves your break-even.

Kalshi charges its trading fee on top of the contract price, so the price you pay is not the probability you have to beat. This calculator adds the fee and shows the real break-even.

How the fee behaves

Kalshi charges 0.07 × C × P × (1 − P), rounded up to the next cent. It is biggest on a coin flip and cheapest out at the edges.

That is exactly backwards from a sportsbook, where the vig sits heaviest on longshots. 100 contracts at 50 cents costs $1.75 in fees, and your break-even moves from 50% to 51.75%.

It is charged on the way in and again on the way out. Settlement is free, so holding to resolution is genuinely cheaper than trading out of a position.

Most tools show you the price and stop there. The price is the number that is wrong.

Want more math?the Nerd Corner

\text{fee} = \big\lceil\, r \cdot C \cdot P\,(1-P) \,\big\rceil_{\text{cent}}, \qquad p_{\text{break-even}} = P + r\,P\,(1-P), \qquad \dfrac{\text{fee}}{C \cdot P} = r\,(1-P)

where:

$C$ : the number of contracts in the fill, a positive integer.
$P$ : the contract price in dollars, strictly between 0 and 1. A 50¢ contract is $P = 0.50$ .
$r$ : the fee rate, $0.07$ for a taker crossing the spread, $0.0175$ for a resting maker order.
$\lceil \cdot \rceil_{\text{cent}}$ : round up to the next whole cent, applied to the total for the fill, not per contract.
$p_{\text{break-even}}$ : the true probability a buyer needs for the trade to return its cost.

Worked at the form’s defaults (100 contracts at 50¢, taker):

\text{fee} = \lceil 0.07 \times 100 \times 0.50 \times 0.50 \rceil = \$1.75, \qquad \text{outlay} = \$50.00 + \$1.75 = \$51.75

p_{\text{break-even}} = 0.50 + 0.07 \times 0.50 \times 0.50 = 51.75\%

How the fee works

The taker fee scales with the variance of the contract, not its price. The $P(1-P)$ term peaks at 50¢ (1.75¢ per contract, the most a taker ever pays) and shrinks toward the tails. That is the mirror image of sportsbook vig, which is heaviest on longshots.

Most fee tables stop there. Divide the fee by the money at risk ( $C \cdot P$ ) and the $P$ cancels: the charge is $r(1-P)$ of the stake, largest at the cheap end. In cents the tails are the bargain; as a share of what you put up they are the most expensive point on the curve.

Price	Taker fee, 100 contracts	Break-even	Fee as % of money at risk
5¢	$0.34	5.33%	6.65%
10¢	$0.63	10.63%	6.30%
25¢	$1.32	26.31%	5.25%
50¢	$1.75	51.75%	3.50%
75¢	$1.32	76.31%	1.75%
90¢	$0.63	90.63%	0.70%
95¢	$0.34	95.33%	0.35%

The fee column is the actual cent-rounded charge on a 100-contract fill; the last two columns use the closed forms $P + r P(1-P)$ and $r(1-P)$ , so 5¢ reads 5.33% rather than the 5.34% the rounded fee gives.

The true break-even

At 50¢ the price implies 50%, but a taker fill needs 51.75%: the fee is 1.75 probability points of edge that must exist before the trade returns its cost. In sportsbook units: 1.75 points at 50¢ against the 2.38 points a de-vigged −110 line charges. Cheaper, not free.

Round trips pay twice; settlement is free

Fees are charged per fill, so entering and later selling before resolution pays on both legs: $3.50 on 100 contracts at 50¢, against $1.75 for the same position held to resolution. Settlement costs nothing, so the calculator prices both paths.

Maker orders, and the flat-fee exception

A resting order that gets filled is charged at $r = 0.0175$ , a quarter of the taker rate: $0.44 on the same 100 contracts at 50¢ instead of $1.75, moving the break-even from 51.75% to 50.44%, a difference of 1.31 probability points on a coin-flip contract.

One exception worth checking the contract page for: some major events carry a flat 0.25% maker fee instead of the variance formula. On a 3¢ contract that flat charge is a meaningful share of the whole price, where the standard formula would charge almost nothing. These are Kalshi’s published standard rates, and the exchange can vary fees by market.

Common mistakes

Reading the price as the break-even. A 50¢ contract does not break even at 50%; every taker fill starts 1.75 points behind.
Calling cheap contracts cheap to trade. In cents the fee is smallest at the tails; as a share of the money at risk it is largest there: 6.65% at 5¢ against 3.50% at 50¢.
Rounding per contract instead of per fill. The cent rounding applies to the total: 1 contract at 50¢ costs 2¢ in fees, while 100 cost exactly $1.75 (1.75¢ each).
Assuming the standard schedule everywhere. The flat 0.25% maker markets break the formula, and the exchange can change rates per market.

Check this number yourself

Three public functions in the MIT-licensed teachersbettextbook package reproduce every number here:

pip install teachersbettextbook

from teachersbettextbook import kalshi_fee, kalshi_breakeven, kalshi_fee_breakdown
kalshi_fee(100, 0.50)                  # 1.75
kalshi_breakeven(0.50)                 # 0.5175
kalshi_fee(100, 0.50, 'maker')         # 0.44
kalshi_fee_breakdown(200, 0.12)        # {'fee': 1.48, 'total_outlay': 25.48, ...}

Same inputs, same output, no account required. How the open and hosted halves split →

Want it beside the de-vig and Kelly tools? Open the Kalshi fee check in the app →

Frequently asked questions

How much are Kalshi's trading fees?

Kalshi's standard taker fee is 0.07 × C × P × (1−P), rounded up to the next cent, for C contracts at price P in dollars. It peaks at 1.75¢ per contract at 50¢ and shrinks toward the tails. Resting maker orders are charged roughly a quarter of that rate, and settlement is free.

What win probability do I need to break even on Kalshi?

Buying at price P as a taker, the true probability has to be at least P + 0.07 × P × (1−P). At 50¢ that is 51.75%: the price alone implies 50%, and the extra 1.75 points are the fee. At 12¢ it is 12.74%, and at 90¢ it is 90.63%.

Why do cheap longshot contracts underperform on Kalshi?

Two stacked effects. The classic favorite–longshot bias means low-priced contracts tend to win less often than their price implies, and the fee is a larger share of the money at risk at low prices: 6.65% at 5¢ against 3.50% at 50¢. Together they raise the edge a cheap contract needs just to reach break-even.

Is the price on your screen fair? The free board puts each Kalshi price beside a de-vigged consensus of the sportsbook lines, every step of the arithmetic shown, both timestamps on every number. See today’s board. No account, no card; the free tier runs two hours behind.