EMERGENCY PREPAREDNESS · CALCULATOR
Find Out What Your Emergency Kit Still Misses
Enter the supplies you already own beside your household size. The checker scores each category against the 72-hour standard and names the gap that would hurt first.
Kit readiness
82%
communications sits at zero: the first fix
- Water covers
- 2.5 daysbenchmark is 3 full days
- Food covers
- 3 daysready-to-eat only counts
- Light and warmth
- 2 of 2 lanterns3 blankets for 4 people
- Aid and comms
- Radio missing
Results update as you type. This is an audit of today's stock, not a promise about next month's shopping.
Almost every household believes it is more ready than it is. The cupboard has some bottled water, a candle jar, a blanket that smells of the last move. When the alert comes, belief meets arithmetic, and the arithmetic usually wins. The difference between those two is what this checker measures.
It is deliberately an audit, not a shopping list. Generators of shopping lists tell you what nobody has. This tool asks what you own today, measures it against the accepted seventy-two-hour standard for your household size, and returns one honest score across six categories.
The score matters less than the story underneath it. Water days, meals on hand, and the single category dragging the whole kit down. Fix that one gap and readiness moves further than buying a seventh candle ever would.
The formula
Readiness = weighted average of category coverage, each capped at 100%; water days = litres / (people x 3)
- coverage
- what share of the 72-hour need one category actually meets today, capped at full.
- weight
- each category's importance in the score. Water and food count 25% each; light, warmth, first aid and comms the rest.
- water days
- how many days everyone can drink at three litres each. The most concrete line in the result.
- weakest category
- the gap that defines the kit. A kit is no readier than its lowest scoring area.
Why three days is the standard everyone plans on
Seventy-two hours is not a round number chosen for posters. It is the honest window in which most disrupted services recover. Storm power crews, road clearance, water repairs and family reunions mostly resolve inside three days, and outside help arrives on that rhythm after a wide-scale event.
The same window appears in every serious guidance document for the same reason. Beyond three days, stockpiling turns into a different, larger project. Within three days, a household can genuinely cover itself with cupboard space and modest spending.
That is why this checker scores against seventy-two hours rather than a fortnight. Meeting the standard is achievable this month. The value is in knowing precisely which part of an achievable standard you have already missed, while fixing it is still cheap.
There is a second virtue to the three-day frame. It is small enough to check honestly in one evening, category by category, with a tape and a notepad. A plan you cannot audit is a wish. This one you can audit tonight, and the tool does the weighting.
- Three days covers most service restoration and first-response windows.
- The standard is cupboard-sized, not bunker-sized. That is the point.
- Readiness you have not counted this month is readiness you do not have.
How the six categories are weighted
Not all gaps bite equally, so the score is weighted. Water and food carry twenty-five percent each, because thirst and hunger set the clock on everything else. Light and warmth take fifteen each, first aid and communications ten each.
Water's weight reflects biology. Households routinely overestimate stored water and underestimate how fast four people at three litres a day empty a shelf. The checker reports water as days, the only unit that makes the number feel real.
Food scores on ready-to-eat meals only. A pantry of dry rice and a broken stove is not food storage in an outage. Anything needing hours of cooking, refrigeration or clean water to prepare does not count toward the three-day window.
Communications carries the smallest weight and the strangest regret. People who lose power and signal report the silence as the unsettling part. A crank radio costs little, and its ten percent is often the cheapest point on the whole board.
Reading your result: the weakest-category rule
The headline number is an average, and averages flatter. A kit scoring eighty percent with a zero in communications is not eighty percent ready when the storm briefing matters most. The weakest category is the true shape of your preparedness, so the result names it first.
That is why the line order matters. Look at the lowest category before the score. Each one has a cheap, bounded fix, and the lowest one usually fixes itself with one small purchase this week rather than a project.
Second place deserves the same attention after that. Fix the radio and warmth may become the story, blankets short by one, no spare for the guest room. The checker re-scores instantly as you update each figure, so you can shop on paper before shopping in person.
A caution against gaming the score. Padding blankets to overkill while water sits at one day produces a healthier number and a worse kit. Coverage caps at full marks in every category for exactly this reason. Meet the standard everywhere before exceeding it anywhere.
Worked example: the family of four on the default shelf
Take the default audit: four people, thirty litres of water, twenty-four meals, two lanterns, three blankets, one first-aid kit, no radio. The water answers 2.5 days for everyone. The food is exactly three days at two meals per person. Light and first aid are full marks.
Two things fall short. Warmth covers three of four people, seventy-five percent. Communications sits at zero, costing the kit its full ten points. The weighted score lands near eighty-two percent, a radio, a blanket and six litres of water away from full marks.
Notice how little money that last stretch needs. A hand-crank radio, a spare emergency blanket and six more litres of water are a weekend's shopping. The audit's real output is not the number. It is the three-line shopping list the number implies.
Now run the same shelf through the prepared rural sample: sixty litres, forty-eight meals, doubles everywhere. The score reaches full marks and the caps hold it there. Overkill earns nothing, which is the tool quietly teaching proportion over panic.
What this audit cannot see, and what to check by hand
The checker counts quantities you enter. It cannot open the fridge to test whether that first-aid kit's plasters are from the previous decade, or plug in the lantern to find dead cells. Audits earn their value only when supplies are genuinely serviceable today.
Some needs resist counting. Medications, baby supplies, a CPAP, pet food and heating fuel are invisible to a six-category model but decisive in a real event. Score them by hand beside the audit result, and treat anything irreplaceable as its own category.
Behaviour is the other blind spot. A kit split between a garage box, a drawer and two bags in the hall fails the practical test even when every count is green. The seventy-two-hour standard quietly includes knowing where everything is in the dark.
Re-run the audit when the household changes. A new baby rewrites water and food. A move loses boxes. A harsh winter raises the warmth bar. Readiness is a maintained state, and the maintenance is ten honest numbers four times a year.
Reference values
The 72-hour benchmark per person behind the score
| Category | Benchmark | Weight |
|---|---|---|
| Drinking water | 3 L per person per day (9 L over 72 h) | 25% |
| Ready-to-eat food | 2 meals per person per day (6 over 72 h) | 25% |
| Light | One working lantern per two people | 15% |
| Warmth | One warm layer per person | 15% |
| First aid | One stocked kit per household | 10% |
| Communications | One emergency radio per household | 10% |
Key terms
- 72-hour standard
- The widely used household benchmark of covering three days unaided, matching typical service-restoration windows.
- Ready-to-eat
- Food needing no cooking, refrigeration or special water. The only food that counts during an outage.
- Coverage
- One category's share of its benchmark, capped at full. Over-stocking one area cannot hide an empty one.
- Weakest category
- The lowest-scoring area of the kit. In practice, the one that defines your real readiness.
Tips and common mistakes
Field-tested tips
- Fix the zero before polishing the eights. One missing category costs more real readiness than a full shelf of anything else.
- Count water in days, not bottles. Litres divided by household thirst is the number that prompts action.
- Date your audit like your cartridges. Run it again after any move, new arrival or change of season.
- Keep the whole kit in one addressable place. A scattered hundred-percent kit still fails the 2 a.m. test.
Common mistakes
- Scoring a pantry of dry ingredients as three days of food when cooking needs are impossible.
- Testing water by memory instead of litres, then discovering four people drink a shelf in a day.
- Treating the average score as the result and ignoring the single category dragging it down.
- Never switching the lantern on. Dead batteries turn a counted supply into an imaginary one.
Frequently asked questions
Is a hundred percent score the goal, or is that overkill?
One hundred percent means meeting the 72-hour standard in every category, not stockpiling beyond it. Coverage is capped at full marks precisely so extra supplies cannot inflate the number. The right answer is a flat sheet of green at exactly one hundred, then stopping. Anything past the standard is better spent on medicine supplies, spare prescriptions and the household's real weak points.
Why does the checker treat my car kit separately?
Because it scores the household shelf, and a household audit assumes everyone is home. A car emergency kit serves a different scenario, on a different road, in different weather, with different tools. The car kit builder here plans that separately. Two scenarios, two audits. Neither score borrows supplies the other needs.
What about people who need more than the benchmarks?
The benchmarks are averages, and averages fail exacting members. Infants, elderly relatives, medical devices, pregnancy and chronic illness all push water, food or first aid above the line. The honest method is to run the audit as-is, then raise the affected category's benchmark by hand and score it again.
Does fixing the weakest category raise the score much?
Usually yes, disproportionately. A zero costs the whole weight of that category, so the first radio adds ten points from nothing, and the fourth blanket closes half of warmth. That is why the result names the weakest area first. The cheapest single purchase on your shelf is almost always the one the audit says you do not have, and the score moves accordingly.
About this calculator
- Written by
- Spare Theory Editorial Team · Research & Testing Desk
- Last reviewed
- 2026-10-16
How we calculateBenchmarks follow published 72-hour household guidance: three litres of water per person per day, no-cook meals, one light per two people, one warm layer each, one first-aid kit and one emergency radio per household. Category weights prioritise biological needs. Coverage is capped at full marks so surplus cannot mask deficits.
Reference basisOfficial emergency preparedness guidance on household 72-hour kits · Public health water-requirement figures for short-term disruption