What it measures
Every candidate has two prices that matter: the chance of winning their party’s nomination and the chance of winning the presidency. The index asks a narrower question than either: if this candidate is the nominee, how likely are they to win?
That separates how strong a candidate would be in November from how likely they are to get there. A long shot for the nomination can still be a strong general-election candidate, and a front-runner can be a weak one.
The formula
It’s a conditional probability: the chance of winning both the nomination and the presidency, divided by the chance of winning the nomination.
The two numerators are nearly identical because a candidate can only reach the White House through their party’s nomination. An independent run or a party switch would break that assumption.
A live example
Alexandria Ocasio-Cortez on Polymarket, . 13.1% divided by 16.3% is 80.3%.
Which prices are used
Each contract pays $1 if it comes true, so its price reads as a probability. Every market quotes a best bid, the highest price a buyer will pay, and a best ask, the lowest price a seller will take.
- Midpoints, not last trades. The index uses the midpoint between the bid and ask. A last trade can be hours old; the midpoint reflects the market now.
- Both prices from one market. A Polymarket presidency price is only ever divided by a Polymarket nomination price, and the same for Kalshi.
- No blending. The two markets settle under different rules, so their results are shown side by side, never averaged.
- Full precision. The division uses unrounded prices. Only the display is rounded.
Who gets ranked
A candidate is ranked only when both of their markets pass every check below. Anyone who misses one is still listed under Not ranked, with their prices and the reason.
| Check | Threshold | Why it matters |
|---|---|---|
| Chance of nomination | 2% or more | Dividing by a small number magnifies noise. At 1%, a one-cent move can halve or double the result. |
| Bid–ask spread | 3 points or less, and under 25% of the price | A wide gap means the market hasn’t settled on a price. |
| Order depth | $100 within 2¢ of the best price, on each side | Keeps one small order from setting the number. |
| Quote range | 20 points or less | The index recalculated from bids and asks has to land in a narrow band. |
| Consistent prices | Presidency no higher than nomination | Otherwise the result would be above 100%, which is impossible. |
When Kalshi’s full order book isn’t available, only the size at the best quote counts toward depth, which is the cautious choice. These checks reduce noise; they don’t certify that a market is right.
Updates
- A collector records prices from both markets every hour, separately from page visits.
- If a market fails to respond, its last good prices stay up with their original time, marked as delayed. Nothing is estimated or filled in.
- Prices more than 90 minutes old are labeled as delayed.
- History begins with the first recorded update. Nothing is back-filled.
Current status for each market is on the Sources page.
Map, comparisons and changes
- The electability map. On the map, each ranked candidate sits across by their chance of winning the nomination and up by their chance of winning if nominated. The across scale is logarithmic, so the many candidates between 2% and 10% don’t crowd together. The curves join points with the same overall chance of winning the presidency, because that chance is the two coordinates multiplied: 20% to be nominated and 50% if nominated, or 12.5% and 80%, both make 10%. Candidates above and to the left of their party’s front-runner are less likely to be nominated but priced as stronger nominees.
- Comparisons. The comparison page sets up to four candidates’ figures side by side, all from one market. They are not matchup odds. Each figure is that candidate’s own chance, from their own prices, not their chance against anyone else on the page: two candidates from the same party can’t both be nominated, and two from different parties may never face each other.
- What changed. The briefing compares the latest recorded prices with those from 24 hours or 7 days earlier on the same market. A move is listed once it reaches 2 points over a day or 3 points over a week and is at least half as wide as the candidate’s range from bid and ask prices, since smaller shifts can happen without a trade as quotes move within the spread.
- Why a number moved. The index is the presidency price divided by the nomination price, so a move is put down to whichever price changed more in proportion: the presidency price when its change is at least twice the nomination price’s, the nomination price in the reverse case, and both otherwise.
Limits
- Conditional, not causal. Each number describes a world where that candidate is the nominee. That world can differ in other ways too: the opponent, the economy, the campaign. A higher number doesn’t prove that nominating someone would raise their party’s chances by the same amount.
- Not a head-to-head poll. It reflects what traders are willing to pay, not a survey of voters.
- Markets can be wrong. Thin trading, fees, the cost of tying up money for years and enthusiastic bettors can all push prices away from true probabilities.
- Settlement rules differ. Kalshi’s presidency contract settles on who is inaugurated; Polymarket’s on how major news outlets call the election. Rare events could split them.
- Nominees can change. A nomination contract resolves when the nomination is won and accepted. A later replacement doesn’t undo it.
Questions
Why don’t the numbers add up to 100%?
Each number answers a separate what-if: this candidate is the nominee. Those scenarios can’t all happen together, so their chances aren’t parts of one whole and aren’t meant to sum to anything.
Why isn’t the most likely nominee always the most electable?
Nomination odds measure strength in a primary. The index measures strength in a general election, given a nomination. A candidate can be a strong favorite with primary voters and still be priced as a weaker general-election candidate, or the reverse.
Can I compare a Democrat’s number with a Republican’s?
Loosely. Both are chances of winning the presidency as the nominee, but each assumes a different likely opponent and a different campaign. Treat cross-party comparisons as context, not a matchup.
Does the comparison page show who would win a head-to-head race?
No. It lines up each candidate’s own prices against the whole field. Markets for a specific pairing, such as one named Democrat against one named Republican, aren’t used anywhere on this site.
Why are well-known candidates missing from the ranking?
Anyone under a 2% chance of nomination, or with prices that are too thin or too far apart, is listed under Not ranked with the reason. Their prices are still shown.
Why are Polymarket and Kalshi numbers different?
They are separate markets with different traders, fees and settlement rules. The index keeps them apart rather than averaging them, so you can see where they agree and where they don’t.
Is this betting or investment advice?
No. It’s a research tool that reads public market prices. It doesn’t recommend trades and isn’t affiliated with either market.