Build the 72-hour kit or buy one? It's closer than you think

The question

Do you assemble a 72-hour kit from scratch, or buy a ready-made one and call it done?

Every number below is a worked example. Swap in your own, and check current prices before you trust any of them.

The Dad Math

Here's how it goes in the driveway, arms folded, one foot on the bumper.

• A ready-made kit for four costs $150 (an example, not a quote).
• I own a flashlight. I own batteries. There are granola bars in the pantry.
• A first aid kit is $10 at the pharmacy. Tap water is free.
• Total to build: about $40.
• Savings: $110, which is a steak dinner and a good drill bit.
• Time required: twenty minutes, one trip, no list. I'll remember everything.

My wife looked at this math and asked one question. "Where's the radio?"

I'd like to say I had an answer. I had a flashlight and a lot of confidence.

The real math

Start with what the official list asks for. Ready.gov's basic supplies include a gallon of water per person per day for at least three days, at least three days of nonperishable food, a battery-powered or hand-crank radio, a flashlight, extra batteries, a first aid kit, a whistle, dust masks, a manual can opener, a wrench or pliers, and a way to keep a phone charged. Add medications, baby supplies, pet food and copies of important papers for your own household.

Now price it for four people over three days. Example prices only.

Building it yourself:

• Water, 12 gallons at $1.50: $18
• Food, 12 person-days at $4: $48
• Radio, battery or hand-crank: $30
• Two flashlights at $10: $20
• Batteries: $10
• First aid kit: $25
• Phone power bank: $25
• Manual can opener: $8
• Whistle, duct tape, dust masks, trash bags, wipes: $20
• Wrench or pliers for the utility shutoff: $12
• A tote or duffel to hold it all: $15

That's $231 in supplies. Now the part the driveway left out. You'll write the list, shop, find that the store is out of something, and make the second trip. Then you'll pack it and label it. Call it three hours. At an example value of $25 an hour, that's $75.

Build total: $306.

Buying a kit and filling the gaps:

Say the $150 kit covers the small stuff like a basic first aid kit, a light, a whistle and a poncho. Say it doesn't include enough water, enough food for four, or a radio. Plenty of kits are sized for fewer people or fewer days, so read the contents list and the headcount before you pay.

• Kit: $150
• Water, food and radio to fill the gap: $18 + $48 + $30 = $96
• One hour to shop and sort: $25

Buy-and-fill total: $271.

So the gap is $35, not $110. If your kit already includes the radio, buying wins by more. If its flashlight is the kind you'd be embarrassed to hand a child, the margin shrinks.

Three more things the driveway never counts:

• Rotation. Food, water and batteries have dates. Many people check their kit twice a year and tie it to the clocks changing. Stored food you eat and replace costs you only the effort.
• Storage. A tote for four takes up roughly one shelf. Keep it somewhere cool, dry and easy to grab, not behind the Christmas decorations.
• The stuff only you know. No box includes your daughter's inhaler, your father's pills, the dog's food or your spare glasses. That's your list whether you build or buy.

One safety note, no joke attached. Only shut off your gas if you smell it or hear it hissing, and know that only the utility can turn it back on. Learn where each shutoff is before you need it, and don't practice on the gas.

The verdict

Do the arithmetic on the kit's contents list, item by item, against your own list. The rule of thumb:

If the kit price plus the gaps plus one hour of your time comes in under your build price plus three hours, buy it and fill the gaps. If it doesn't, build.

Run it on your own numbers and it usually lands within a pizza or two of a tie. That means money isn't the deciding factor. These are:

• Buy if you know you'll never write the list. A kit sitting in the closet beats a perfect list sitting in your head.
• Build if you want to know what's in every pocket and have the radio, lights and tools be ones you'd trust.
• Do both if you're honest about who you are. Buy the base, then spend a Saturday morning adding water, food, medications and the radio.

The radio and the flashlights also work in an ordinary outage or on a camping trip. That spreads their cost over many uses, which the BRO cost-per-use calculator will show you in a minute. The water and the first aid kit you hope to use once, if at all.

For what to put in the kit and how to get the family to use it, read the seventy-two hour kit your family will actually use. Add the radio that still works when the internet doesn't if yours is still on the "I'll remember" list. And set aside some cash you can actually reach, because the card reader goes dark with the power.

The cheapest kit on paper is the one with the radio missing. My wife knew that in the driveway. I found out in the checkout line.