The rule of thumb for this is whatever you think is the minimum you need, it is too much. It is easy to imagine that at some point, you will really want some item and so, you pack it. But there is far too much that falls into this category. What you really need is dictated mainly by (1) the basic paperwork that keeps you legal (2) the geographic setting(s) you will travel through, and (3) what tools you need to document where you are, keep planning ahead for later destinations, and keep track of your finances, and (4) things to occupy your time when sitting around waiting for the bus to leave.
Your Papers Are Not In Order!
This stuff is obvious; the passports, any special documents for visas, printed tickets (of which you have no digital record) credit cards, and anything else that is absolutely mission critical. I only mention it because of the importance of storing it securely. As a habit, I never store the above things in a bag. They go directly on my body, in a money belt or some similar apparatus that is under clothing, ideally invisible, and at any rate, difficult for someone to get at without detection. This can be rather challenging in airports and land borders, where you may have to drag out your passport more than once.
Clothing
A lot can be done with a few pieces of clothing. If temperature is variable, things can be layered as necessary. I have taken one pair of shoes, which aren’t quite hiking boots but aren’t just street shoes either, and are waterproof. A heavy coat should only be considered (due to the volume it takes up) if really low temperatures are expected. Though this is the case with us early in the trip, I plan to ditch it when we’ve moved into warmer areas. No more than three or four pairs of socks and underwear. Four shirts, one or two of them ‘nicer’ (ie with collars), and most with long sleeves for some added UV protection. A few pairs of long pants with multiple pockets (no jeans), and a few short pants. Janet has one dress. Good hats, gloves, and sunglasses for all of us, and rain jackets with hoods. Two compact umbrellas. Any replacement clothing due to wear or loss will have to happen as the situation arises.
Documentation and Tools for Working
I spent a lot of time looking at how other families were documenting their trips, which is one reason I decided to create this admittedly basic website. But to properly capture the trip in a way that (hopefully) will be enriching for site visitors, we needed more than just cell phone pictures. To this end, I brought a GoPro with a few different ways to attach it to myself, an additional adjustable digital camera that is more flexible than a cell phone, and a number of programs and cell phone apps to deal with editing and mapping routes. Not much of this takes up much space, but it does increase weight.
Tools for working means anything that brings in money while you are on the road. The one common denominator in any digital nomad work is a computer. My primary consideration with buying our ‘travel computer’ was weight. There are a fair number of new laptops that weigh under 3 pounds, which makes a big difference in a carry-on bag. Our computer serves the purposes of work station for my remote job, a picture and video editor as well as digital storage, and one of our daughter’s interfaces for school work. We also have a tablet with a Bluetooth connection to our phones and the computer. Keeping photos and such in the Cloud, as well as sites like Mega, ideally eliminates the danger of losing everything in the event that any or all of the devices are lost or destroyed. Lastly, all these devices keep track of reservations and budgeting details.
Idle Time
Books weigh a lot, so we’ve taken as few as we can. Guidebooks have been my priority, and only a few of them are actually in printed form. Stuff to read for fun is also mostly digital, and family games are restricted to small items like a deck of cards. There are many options for use of digital material in libraries, our (formerly) home library ‘checks out’ books that get ‘returned’ just the same as printed matter. There are some large nationally known libraries in the US that will do the same, for a yearly fee.
Having said all that, in my experience, travel really is not much about idle time anyway. The problem is often the opposite: So much is going on that I barely have time to keep track of what happened on any given day.