A device and method corrects time data based on a clock signal affected by jitter. The error due to jitter in a time measurement of an event in the clock signal is determined at the time of the event or as an average over a number of events. A measurement is made of a time dependent reference variable associated with a long-time constant device, such as a capacitor, which is relatively immune to localized jitter. The measurement may be a reading of the voltage across a charging capacitor. The measured value is compared to an expected value, and the time error is based on the result. The expected value may be stored or calculated from known charging rates of the capacitor. The error due to jitter of a time measurement is approximately linearly proportional to the difference in voltage between the measured and the expected values of the capacitor.