You can find the postal code of all the districts of Nepal in this postcode: Nepal. Here, when you use the postal code, you should use the postal code of the post office of the address that is closest to you.
How to find the postal code for your district
Click on your province below, and after that, all the districts in that province will come up. Click on your district, and you can easily use the 5-digit postal code near your home or place of residence.