Knife Design
Building a shelter and making fire both involve the manipulation of wood, so you’ll need a strong knife that will hold its edge. And because sturdiness is so important—a knife won’t help you survive if it breaks during hard use—we generally recommend a fixed-blade (as in, not folding) survival knife with a full-tang construction, meaning the steel of the blade extends all the way through the handle. Full-tang knives are best for practicing bushcraft techniques too. If you just want a reliable knife to keep in your glove box, purse, or pocket, then a folding knife will work fine.
Size
For a dedicated survival knife, bigger is typically better. But not too big. A good and generally accepted size for the category is around nine inches, plus or minus a few. But again, the best survival knife is the one you have with you when disaster strikes—any blade is better than none at all, and there are exceptions to every rule.
Color
There are some survival knife considerations that don’t specifically pertain to pure function. First: I’m favorably predisposed toward bright orange for knives and outdoor tools when that’s an option. Survival situations can often involve low visibility, so having a camo knife would be a dumb idea. We’re also steering clear of most search results you’ll find on Amazon—if you ask me, the last thing I want to rely on in a survival situation is some bootleg blade from Bezos.
Sharpening Tools
Second: Keeping your knife sharp is important. It is a blade after all. I sharpen all my knives (kitchen and outdoor) on a Japanese whetstone. This can be an involved but rewarding process that I won’t go into too much detail about. If you’re interested in learning about knife sharpening this way, there’s dozens of videos on YouTube and a ton of crabby knife sharpening “experts” on Reddit who would be more than happy to preach their gospel to you. For those of you that plan on being away from your home sharpening tools, there are some less cumbersome options but, as with everything else mentioned earlier, this requires planning. A good mobile option is the Fallkniven DC4 whetstone. It is small enough to keep in a bugout bag or survival kit and could help in a pinch if you’ve dulled your blade after hours of surviving with it.