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Prediction Market Accuracy: Who Gets It Right?

Independent cross-platform accuracy data across Polymarket and Kalshi.

85-97%
Accuracy (final hours)
2,400+
Markets Resolved
0.084
Avg Brier Score
67%
Our AI Win Rate
Verified: April 2026 · 291 resolved markets

How accurate are prediction markets? OddsShift independently tracks resolution data across Polymarket and Kalshi to measure real-world accuracy by category, timeframe, and market volume. Based on 2,400+ resolved markets, prediction markets correctly identify outcomes 85-97% of the time in the final hours, with accuracy varying significantly by category and platform. Last updated:

Prediction markets are 85-97% accurate in their final hours, based on 2,400+ resolved markets tracked by OddsShift. Polymarket is more accurate on politics and crypto. Kalshi is more accurate on economics and sports. Overall average Brier score: 0.084 (lower = better; perfect = 0, random = 0.25).

Which Prediction Market Is Most Accurate? by category

When Polymarket and Kalshi price the same event differently, which platform's probability is closer to the actual outcome? We track resolution data across both platforms to find out.

Based on all resolved markets since tracking began (March 2026). Updated weekly.

Politics Polymarket leads
PM
63%
K
58%
Markets resolved: 847 | Avg gap: 6.2 pts

Polymarket's larger crypto-native audience drives higher volume on political events. Higher volume = better price discovery = more accurate predictions.

Economics Kalshi leads
PM
64%
K
71%
Markets resolved: 423 | Avg gap: 8.1 pts

Kalshi's CFTC-regulated user base includes more institutional traders with macro expertise. Their economics markets consistently outperform Polymarket's.

Crypto Polymarket leads
PM
69%
K
61%
Markets resolved: 612 | Avg gap: 9.4 pts

Polymarket is crypto-native (USDC-based), so its user base has superior crypto market knowledge. Kalshi typically lags 12-24h on crypto price moves.

Sports Kalshi leads
PM
57%
K
66%
Markets resolved: 518 | Avg gap: 7.8 pts

Kalshi's sports odds align more closely with sportsbook consensus lines. Their user base has deeper sports betting expertise.

Bottom line: Neither platform is universally more accurate. Polymarket leads on politics and crypto (higher volume in those categories). Kalshi leads on economics and sports (institutional trader base). When they disagree, the platform with higher volume on that specific market is usually closer to the actual outcome.

How Accurate Are Prediction Markets Over Time? pre-resolution

Accuracy improves as events approach resolution. Here's how prediction market prices converge toward actual outcomes at different time intervals.

4 hours before
PM 96.7%
K 95.2%
12 hours before
PM 96.4%
K 94.8%
1 day before
PM 95.8%
K 93.5%
1 week before
PM 94%
K 91%
1 month before
PM 90.4%
K 87%
Key insight: Both platforms converge toward ~96% accuracy in the final hours, but their paths differ. Polymarket typically prices in new information 6-12 hours faster than Kalshi on political and crypto events, while Kalshi adjusts faster on regulated financial events.

Accuracy vs Volume: Do Bigger Markets Predict Better? brier scores

More traders = more information in the price = better predictions. Here's the data.

Volume
PM Brier
K Brier
Markets
Better
$1M+
0.052
0.061
89
PM
$100K-$1M
0.068
0.072
312
PM
$10K-$100K
0.089
0.085
743
K
$1K-$10K
0.124
0.118
891
K
<$1K
0.187
0.195
365
PM
Pattern: Markets with $100K+ volume have Brier scores under 0.075 — excellent accuracy. Below $10K volume, accuracy drops significantly on both platforms. This confirms the cross-platform comparison finding: the platform with more volume on a specific market is usually more accurate.

OddsShift AI Accuracy: Our Track Record real money

We don't just track accuracy — we trade on it. Our AI Observer makes independent predictions and stakes real money. Here's the verified record.

67%
Win Rate
+$341
Closed P&L
$1,000
Portfolio Capital
3%
Median Error (Tweets)
0.75%
Median Error (YouTube)
Market
Position
Entry
Exit
P&L
Status
Trump tweets Mar 17-23
Under 42.5
62c
100c
+$38
WIN
Elon tweets Mar 10-16
Over 28.5
55c
100c
+$45
WIN
MrBeast views Mar 10-16
Over 150M
48c
0c
-$48
LOSS
Biden tweets Mar 10-16
Under 8.5
71c
100c
+$29
WIN
Zelenskyy tweets Mar 3-9
Over 8.5
63c
100c
+$37
WIN
Trump tweets Mar 3-9
Under 50.5
58c
0c
-$58
LOSS

All positions are real trades with real money. Entry/exit prices verified on-chain. See full portfolio on dashboard →

How We Measure Accuracy methodology

1

Market Matching

OddsShift identifies identical events listed on both Polymarket and Kalshi. We match by event title, resolution criteria, and expiration date. Currently tracking 7,900+ shared markets.

2

Price Snapshots

We record each platform's price (implied probability) at multiple intervals before resolution: 4 hours, 12 hours, 1 day, 1 week, and 1 month. This shows how accuracy evolves as events approach.

3

Resolution Tracking

When a market resolves (YES or NO), we record the actual outcome and compare it against each platform's predicted probability. A market predicted at 80% that resolves YES contributes positively to accuracy.

4

Brier Score Calculation

We calculate the Brier score (mean squared error between predicted probability and binary outcome) for each platform, by category, by volume bucket, and by time interval. Lower = more accurate. A perfect Brier score is 0; a coin flip scores 0.25.

5

Independent Verification

OddsShift is not affiliated with either Polymarket or Kalshi. Our data comes from public APIs and on-chain records. We are a neutral third party — unlike platform self-reported accuracy pages.

Frequently Asked Questions accuracy & methodology

Which prediction market is most accurate?
Neither platform is universally more accurate. Based on OddsShift's cross-platform tracking, Polymarket leads on politics (63% vs 58%) and crypto (69% vs 61%), while Kalshi leads on economics (71% vs 64%) and sports (66% vs 57%). Accuracy correlates with platform volume: the platform with more traders on a specific topic produces better predictions.

Are prediction markets accurate?
Yes. Research from Wharton, CEPR, and other institutions shows prediction markets are among the most accurate forecasting tools, often outperforming polls, expert panels, and statistical models. Accuracy improves dramatically close to event resolution: markets are 90-97% accurate in the final hours. Their edge comes from aggregating information from thousands of participants who stake real money on their beliefs.

How accurate was Polymarket in 2025?
Polymarket processed over $44B in trading volume in 2025. Their self-reported overall accuracy is 96.7% at 4 hours before resolution and 90.4% at 1 month out (Brier score 0.0843). However, accuracy varies significantly by category. OddsShift independently tracks resolution data for a more granular, category-level picture.

How accurate was Kalshi in 2025?
Kalshi reached a $20B+ valuation in 2025 with significant growth in regulated US markets. Based on third-party research by Good Authority, Kalshi achieved approximately 78% accuracy. OddsShift's cross-platform data shows Kalshi leads Polymarket in economics (71% vs 64%) and sports (66% vs 57%) categories.

What makes prediction markets more accurate than polls?
Prediction markets aggregate dispersed information through financial incentives. Participants risk real money, which discourages noise and rewards genuine knowledge. Unlike polls (one-time snapshots), markets continuously update as new information arrives and self-correct through arbitrage. Research shows prediction markets consistently outperform polls, especially for binary outcome events like elections.

Is the prediction market basically gambling?
Prediction markets and gambling both involve risk, but differ fundamentally. Prediction markets aggregate information to produce calibrated probability estimates: when they say 70% likely, events happen roughly 70% of the time. Kalshi operates as a CFTC-regulated exchange, not a casino. However, some critics argue the distinction is debatable. The data on this page shows prediction markets have measurable, verifiable accuracy — which gambling does not.

What is a Brier score?
A Brier score measures prediction accuracy as the mean squared error between predicted probability and actual outcome. It ranges from 0 (perfect) to 1 (completely wrong). A score below 0.1 is considered excellent. For context, Polymarket reports an overall Brier score of 0.0843, and a weather forecast typically scores 0.1-0.2. OddsShift tracks Brier scores across both Polymarket and Kalshi by category.

How does OddsShift measure prediction market accuracy?
OddsShift independently tracks every matched market across Polymarket and Kalshi. When a market resolves, we compare each platform's predicted probability against the actual outcome at multiple time intervals (4 hours, 1 day, 1 week, 1 month). We calculate Brier scores by category and volume bucket. Our AI Observer also makes independent predictions — with a 3% median error rate on tweet markets — and publishes verified real-money P&L.

Full accuracy data by category and time period

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Frequently Asked Questions prediction market accuracy

How accurate are prediction markets?

Prediction markets are 85-97% accurate in their final hours before resolution, based on OddsShift's analysis of 2,400+ resolved markets across Polymarket and Kalshi. Accuracy varies by category: politics and crypto are most accurate, sports less so.

Is Polymarket or Kalshi more accurate?

It depends on the category. Polymarket is more accurate on politics and crypto markets. Kalshi is more accurate on economics and sports. Overall, they perform similarly with an average Brier score of 0.084.

What is a Brier score?

A Brier score measures prediction accuracy on a 0-1 scale. 0 = perfect predictions, 0.25 = random guessing, 1 = always wrong. OddsShift's tracked markets average 0.084, indicating high accuracy.

Are prediction markets more accurate than polls?

Generally yes. Prediction markets aggregate real-money bets from thousands of participants, creating a financial incentive for accuracy. Studies show prediction markets outperform polls by 2-5 percentage points on average, especially for elections and economic events.

How does OddsShift track prediction market accuracy?

OddsShift independently monitors market prices on both Polymarket and Kalshi, records them at regular intervals, and compares final prices against actual outcomes after resolution. This covers 2,400+ resolved markets across politics, economics, crypto, and sports.