Polymarket's prediction accuracy varies significantly depending on the time frame and market type, according to data from their site and a Dune analysis. As of 2025, Polymarket reports a 95.2% accuracy rate at 4 hours, decreasing to 89.8% at 12 hours, 88.6% at 1 day, 88.9% at 1 week, and 91.3% at 1 month. The Dune analysis indicates an overall accuracy of approximately 90%, which improves to 92% in the final 4 hours before event outcomes. The analysis also reveals biases in different market types, with long-odds markets showing higher accuracy compared to sports markets, where accuracy increases over time. However, detailed category data for politics and crypto markets is not separately provided. Additionally, sources suggest a slight overestimation of probabilities in Polymarket's predictions.