Real-Time Clock Calculator

Use this calculator to convert between formats for time-keeping accuracy measurements and to determine the crystal frequency error as a function of the temperature response of the crystal.


Enter desired operating temperature. Enter desired deviation in ppm, sec/day, OR min/yr. Click the 'calculate' button next to your entry to calculate the corresponding accuracy and error measurements.

Note: Temperature dependent crystal frequency error in ppm is determined using the formula:

Error (ppm) = -0.042(25 - OperTemp)2

Also see: DS3231 I2C RTC