How much does backpack offloading cost?

On most treks, it costs approximately Rs. 250 per day per backpack, plus 5% GST.
In some cases, it might go up to Rs. 300 per day. This depends on the trek.

If the trek is longer and tougher operationally, then the cost of the mule or porter increases.

It also depends on what the local people in the trek basecamp charge for carrying the backpacks.