How to pack for a trek in Nepal
A bag for your porter
The best type of bag for your porter is a large, comfortable rucksack, the same as you might carry all your gear in when backpacking. We allow up to 18Kg of load for each porter, which is about what a large rucksack will fit, as long as it's not just full of batteries and red bull.
Split between two
Usually, a porter is shared between two people, so that would mean sharing a single, large rucksack. This can work out perfectly however, because two people are likely to be travelling with a big bag each, so pick the biggest / most comfortable for your porter, and with the other...
Leave a bag at your hotel
Most hotels, and certainly any we organise, allow you to leave our bag in secure storage when you go for a trek. If two people are sharing a porter, simply use the other person's bag to store all the gear you don't need for your trek, so you never have to take more than you need and can save your weight allowance for the important stuff. If you're worried about security (not usually an issue) you might want to take a couple of little padlocks for your bag zips, or use a Pacsafe Exomesh (this is great for peace of mind on long term travel).
Sharing your rucksack space
To keep things easy for both of you, pack your things into different coloured dry bags or stuff sacks, that way everything stays together and you can tell what's yours as soon as you open the bag. Maybe even assign a few colours each (or just whatever patterned bags or stuff sack you happen to have), so you can each have a colour for toiletries and a colour for clothes, for instance. You'll soon figure out the best way these pack in to your bag too, so packing and unpacking at your camp or tea house will become super fast.
If you're a solo trekker
The above still applies if you're trekking alone. but you have the luxury of the whole weight allowance to yourself. We suggest simply taking a lightweight, packable duffel bag with you on your trip which you can use to store your extra gear at your hotel.
On the trail
Each day you'll need a few essentials - sun screen, extra layers, trail snacks and water. You'll want these with you, as often your porter will go ahead and be waiting at your destination with your main pack. To carry these bits all day long, you'll need a comfortable day pack. 20 to 25 litres is a good size, and some ventilation on the back panel can be handy. We're also big fans of water bladders in our day packs, as it's a lot easier to keep up with essential hydration when you don't have to keep stopping to drink.
A last note about batteries...
Many people don't know this, but low temperatures can drain batteries even without using them. You want to start your trek with charged batteries and keep them charged until you need them (using power can be expensive at high altitude). Keep them warm by storing them in a small, slim pouch close to your body in the day (for instance in the map pocket of your mid layer), then in the bottom of your sleeping bag overnight. Also, be sure to turn off your camera and phone when you're not using it to save that essential juice!