5 things that help you build an emergency kit that fits in one box

The container is the discipline. Without a fixed boundary — a physical box you cannot expand — you will keep adding things until you have a cargo-net hammock of protein bars and a hand-crank radio from 2009. The box enforces ruthlessness: every new item has to justify why it belongs more than something already inside. A robust 35–40 litre plastic crate with a lid is ideal: you can see inside, it seals against damp, and it fits in a hall cupboard. A wheelie suitcase sounds practical until you try to carry it down a stairwell in the dark.

The single most common mistake is thinking about phone charging when the power is already gone — at which point every portable charger in a five-mile radius has sold out and your battery is at 60% and falling. A good 20,000mAh power bank earns its place in the box because it does three jobs at once: it is your phone charger, your light source (pair it with a collapsible USB LED lantern), and your radio power if you add a small USB camping radio. The phone itself is your most useful emergency tool by some distance — it is your torch, your weather forecast, your family-contact list, and your way of knowing when the grid is coming back.

A full freezer keeps food safe for roughly 48 hours after a power cut; a half-empty one manages about 24 — the air gaps are where the cold bleeds out. The USDA guidance is clear: once your fridge hits 4°C and has been there for more than two hours, perishables need to go. But you can push that window substantially by filling the empty space in your freezer now, before any outage, with bottles of tap water. They become ice; ice becomes your cold buffer; cold buffer buys time. This is entirely free and takes four minutes.

A hand torch is maddening the moment you need to do anything — make food, find something in a bag, comfort a child, check the fuse board. A headtorch leaves both hands free and costs £8–15 for a perfectly adequate one. The second non-obvious part is batteries: a headtorch is useless if the batteries are the ones you put in three years ago. Fresh lithium AAs last significantly longer than alkaline in cold conditions, which is exactly when you will need them most — a useful detail if power goes out during a winter storm and your flat is getting chilly.

Phone contacts are useless when your phone is dead or out of signal. The numbers that matter in an outage are narrow: your energy supplier's 24-hour fault line (in the UK, 105 connects you to your network operator free from any phone, no credit needed), your closest contact who lives somewhere else, and your building manager or landlord if you rent. That is the whole list. I found this out the embarrassing way when I needed to call the energy supplier at midnight with a phone at 4% and realised I had absolutely no idea what the number was. A card in the box — actual paper, actual biro — survives everything and takes three minutes to make.