Use the ILAC G24 staircase method to determine whether to extend, shorten, or maintain your calibration interval based on historical pass/fail data.
The ILAC G24 Method 1 (staircase) adjusts calibration intervals based on results. If an instrument passes calibration consecutively, the interval is extended by a fixed factor (typically 20%). If it fails, the interval is shortened. This approach balances measurement reliability against calibration costs.
A minimum of 3 consecutive in-tolerance results is typically required before extending an interval. However, more data provides better confidence. Most standards recommend at least 5-10 calibration cycles before making interval adjustments.
Most regulated industries target 95% reliability (meaning 95% of instruments should be found in-tolerance at their next calibration). Aerospace (AS9100) and medical device (ISO 13485) organizations may require higher reliability targets.