The validity period of the EWB is calculated based on the ‘approx. distance’ entered while generating the EWB. For every 100 Kms one day is a validity period for EWB as per rule and for part of 100 KM one more day is added. For ex. If approx. distance is 310 Kms then validity period is 3+1 days. For movement of Over Dimensional Cargo (ODC), the validity is one day for every 20 KM (instead of 100 KM) and for every 20KM or part thereof one more day is added. Please refer relevant rules for details.