Prediction Markets / Breakeven Calculator
Breakeven Probability Calculator
A contract pays $1 if it resolves the way you bought it. So the price you pay — the trading fee included — is the probability it demands: buy at 51.75¢ all-in and the outcome has to happen 51.75% of the time for the position to come out level. Type a price, a size and your own probability; the page prints the breakeven number on both venues, from each one's published schedule as read 21 September 2026 (Kalshi, Polymarket, Polymarket US).
Kalshitaker · 0.07
Polymarkettaker · 0.04
The fee is paid once, up front, whichever way the question resolves, so it sits on top of the price in every row above. Neither venue's bid–ask spread is modelled here, and neither is any deposit or withdrawal cost an intermediary may charge.
The calculator is free and needs no account. A free account lets you bookmark the questions you are pricing and follow how their prices move. We never hold funds or place trades.
Create a free accountWhat the two numbers mean
The odds converter answers what a price means and the fee calculator answers what it costs. This page answers the third question: what the outcome has to be worth before the price stops being a fair one.
Breakeven probability
A fact about the price, not about the world. Add the trading fee to the stake, divide by the contract count, and read the result as a percentage — that is the chance at which the position returns exactly what it cost.
Value at your probability
Each contract is worth your own probability, in dollars, and cost the price; the fee is paid once. Multiply, subtract, and you have what the arithmetic calls the expected value of the position at the number you typed — the calculator supplies the arithmetic, never the number.
Breakeven probability by price — Kalshi vs Polymarket
Taker orders, 100 contracts, per each venue's published schedule. The Polymarket column follows the schedule selected above — Politics · Finance · Tech · Mentions — 0.04. A resting maker order pays no fee on either venue, so its breakeven is the price in column one.
| Price | Kalshi breakeven | Polymarket breakeven | Kalshi extra | Polymarket extra |
|---|---|---|---|---|
| 5¢ | 5.34% | 5.19% | +0.34 pts | +0.19 pts |
| 10¢ | 10.63% | 10.36% | +0.63 pts | +0.36 pts |
| 25¢ | 26.32% | 25.75% | +1.32 pts | +0.75 pts |
| 40¢ | 41.68% | 40.96% | +1.68 pts | +0.96 pts |
| 50¢ | 51.75% | 51.00% | +1.75 pts | +1.00 pts |
| 60¢ | 61.68% | 60.96% | +1.68 pts | +0.96 pts |
| 75¢ | 76.32% | 75.75% | +1.32 pts | +0.75 pts |
| 90¢ | 90.63% | 90.36% | +0.63 pts | +0.36 pts |
| 95¢ | 95.34% | 95.19% | +0.34 pts | +0.19 pts |
The last two columns are the reason this page exists: the fee costs the most percentage points exactly where a question is hardest to call. Work the fee itself out on the fee calculator, or turn any of these prices into American or decimal odds with the odds converter.
Questions people ask
What is breakeven probability?+–
It is the chance an outcome needs for a contract to be worth what you paid for it. A contract pays $1 if it resolves the way you bought and $0 if it does not, so a position that cost 51.75¢ per contract once the trading fee is included comes out level at 51.75%. The calculator above prints that number for Kalshi and for Polymarket side by side.
How do I work out breakeven on Kalshi?+–
Add the trading fee to the stake, then divide by the number of contracts. Kalshi charges takers 0.07 × contracts × P × (1 − P), rounded up, so 100 contracts at 50¢ cost $50.00 plus a $1.75 fee — 51.75¢ per contract, a breakeven probability of 51.75%. A resting maker order on a standard Kalshi market pays no fee, so its breakeven is simply the price.
Why does the fee change the probability I need?+–
Because you pay the fee whichever way the question resolves, while the contract still pays at most $1. Both venues size the fee as rate × contracts × P × (1 − P), which is largest at 50¢ and close to nothing near the extremes, so the gap between the price and the breakeven probability is widest on a coin-flip question.
What does “value at your probability” mean?+–
It is arithmetic on the number you typed, nothing more: contracts × (your probability − the price) − the fee. Type 55% against 100 Kalshi contracts bought at 50¢ and it reads $5.00 − $1.75 = $3.25. The calculator has no view on whether 55% is the right number; it only says what your own number implies.
Does a NO contract have its own breakeven?+–
Yes, and it is the other half of the same dollar. A question quoted at 40¢ YES is 60¢ NO, so a NO contract needs a 60% chance plus its fee to come out level. Both venues compute the fee from P × (1 − P), which is symmetric about 50¢, so the fee is the same number on either side of the question.
Which venue needs the lower probability?+–
Whichever charges you less on the same trade, which depends on the category. Polymarket's global taker rate is 0.04 on politics, finance, tech and mentions, 0.05 on sports, economics, culture, weather and other, and 0.07 on crypto; geopolitics markets are fee-free. Polymarket US charges takers a flat 0.0695 on every market, and Kalshi charges takers 0.07. Polymarket never charges makers, and Kalshi's maker multiplier defaults to 0 outside the series its schedule lists as non-standard. Pick the schedule above and the calculator applies it.
Can these fee figures change?+–
Yes, and they do. Each market's own fee parameters are authoritative, and both venues have changed rates during 2026. The figures here were read from the venues' published schedules on 21 September 2026 and every one of them is linked from this page. This is a calculator, not financial advice.
Know the number before you pay it.
Matched questions across Polymarket, Kalshi and Manifold, both quotes side by side — free, no login.
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