|The 'Standard' calibration on an EKG is TWO large boxes VERTICAL. This will be shown at the beginning or end of an EKG printout. If you do not see the calibration marks, it is assumed to be Standard. Note the calibration marks at the END of the EKG printout below. Class, sometimes the Standard calibration marks are a little difficult to read, so look closely. SEE below. This is a standard calibration.