Reliability diagram & calibration checker.
Are your probability forecasts calibrated — does a 70% prediction actually happen about 70% of the time? Paste your predictions and outcomes below and get a reliability diagram, Brier score and calibration error. It runs entirely in your browser — nothing is uploaded.
One row per forecast: predicted_probability, outcome. Probability 0–1 (or 0–100), outcome 0/1 (or loss/win, false/true). A header row is fine. Commas, spaces or tabs.
predicted probability (x) vs. observed frequency (y) · dot size ∝ sample · the closer to the dashed 45° line, the better calibrated
Calibration is a number meaning what it says.
Group every forecast by the probability you assigned, then check how often the event actually happened. A well-calibrated forecaster's dots sit on the 45° line: when they say 70%, it happens about 70% of the time. Brier score is the mean squared error of your probabilities; calibration error is the average gap between predicted and observed across bins.