Where the figures come from: sources and methodology

Reviewed on

How we work: every figure on the site comes from an official source (civil protection, health services or food safety agencies) or a recognized technical reference, and is checked on the original website. When sources disagree, we say so and choose the most cautious figure. We review the content regularly and show the date of the latest review. If an official reference changes, it's changed here.

ItemFigure
Water per person per day3 L per adult: 1.5 L for drinking, 0.5 L for cooking and 1 L for basic hygiene. 3.5 L for people over 65 and 2.5 L for children (BLE (Germany), 10-day supply table, 2024; Ready.gov (US) recommends 3.8 L (1 gallon) for drinking and hygiene; Sweden, 3–5 L)
Basic hygiene2–6 L per person per day (the calculator uses 1 L, the minimum; store more if you can) (Sphere Handbook, minimum standards for water and sanitation)
Intense heatIt can double the water needed for drinking (Ready.gov (FEMA))
Breastfeeding+700 ml of water and about +500 kcal a day (EFSA, reference values for water (2010) and energy (2013))
Energy2,200 kcal per adult; 1,900 for people over 65; 1,800 for children aged 7 to 13 and 1,300 for ages 3 to 6 (BLE (supply planning) and D-A-CH reference values (moderate activity, average of boys and girls))
Kilos of foodActual net weight of what's on the list; Germany's official reference is around 14 kg per person for 10 days (BLE, "Vorratstabelle Mischkost", 2024)
Water for petsAbout 50–60 ml per kg per day: small dog 0.4 L, medium 1 L, large 2 L; cat 0.3 L (Common veterinary reference (it varies with heat, activity and wet food). Canada asks for more margin: 4 L a day per medium dog and 1 L per cat)
Food for petsDry food per day: small dog (~7 kg) 140 g, medium (~17 kg) 265 g, large (~35 kg) 455 g; cat (~4 kg) 55 g. For wet food, about 4 times the weight (FEDIAF (maintenance energy: dogs 110 kcal × kg^0.75; indoor or neutered cats 52–75 kcal × kg^0.67) and dry food of ~3,500 kcal/kg. Check the table on the bag: your brand's comes first)
Days of supplies for petsThe same as for people: Ready.gov and FEMA ask for at least 3 days; the American Red Cross, 5; some US counties, 7–10 (Ready.gov (FEMA), American Red Cross and Catalan Civil Protection (food, water, bowls, medication, carrier, leash and muzzle))
Food in a blackoutFridge: 4 hours. Full freezer: 48 hours; half full: 24 hours (with the door closed) (USDA (Food Safety and Inspection Service, FSIS))
GeneratorsAlways outdoors and more than 6 m (20 feet) from doors, windows and vents (CDC)
Boiling water1 minute; 3 minutes above 2,000 m (6,500 feet) (CDC)
Bleach2 drops per liter of 5–8% bleach (4 if cloudy) and a 30-minute wait (CDC and EPA. In Spain, only bleach labeled as suitable for disinfecting drinking water)
Rotating stored waterEvery 6 months if it's tap water; bottled water, by its date (Ready.gov (FEMA) and CDC)
Moving water15 cm (6 in) knocks over an adult; 30 cm (1 ft) sweeps away a small car; 45–60 cm (1.5–2 ft), an SUV (National Weather Service (US))
Food date labels"Best before": quality (canned food, rice, pasta, legumes, oil, cookies, honey); safe afterwards if the pack is intact. "Use by": safety; don't eat after the date (AESAN (Spanish Agency for Food Safety and Nutrition))
Physical activityAdults and older people: 150–300 min a week of moderate activity (or 75–150 of vigorous) and strength on 2 or more days. Over 65: also balance and strength on 3 or more days. Children aged 5 to 17: an average of 60 min a day, with vigorous and strength activity on 3 days (WHO, "Guidelines on physical activity and sedentary behaviour", 2020)
Chair and balance testsFrom age 60, standing up from a chair fewer times than expected for your age, or not lasting 10 s with one foot in front of the other, points to a higher risk of falls (CDC (US), STEADI fall prevention program)
During an earthquakeDrop, cover and hold on until it stops. Running out during the shaking exposes you to glass and debris; a doorway doesn't protect you any better than a table (Great ShakeOut (FEMA and US emergency services) and Civil Protection (Spain))
Masks and wildfire smokeN95/FFP2 masks filter fine smoke particles, but not gases such as carbon monoxide (EPA and CDC (US), AirNow)
Time to get out of a burning house2 minutes or less from when the alarm sounds (American Red Cross)
Smoke alarmsIn homes with working smoke alarms, the death rate from fires is 55% lower (NFPA (National Fire Protection Association, US), "Smoke Alarms in U.S. Home Fires")
Warning signals for your car in SpainSince January 1, 2026, the connected V-16 beacon replaces warning triangles in Spain. When getting out of the car on intercity roads, wear a reflective vest (DGT (Spanish traffic authority) · Royal Decree 159/2021)
Stranded in the car by snowStay in the car; run the engine about 10 minutes every hour, with the exhaust pipe clear and a window slightly open (National Weather Service and Ready.gov (US))
PMR446 walkie-talkiesLicence-free use in the EU and the UK: 16 channels, 0.5 W maximum and a fixed antenna. Real range of 0.5–3 km in a city (CEPT, Decision ECC/DEC/(15)05)
International mountain distress signal6 signals a minute (blasts, flashes), a one-minute pause and repeat; the reply is 3 a minute (International Commission for Alpine Rescue (IKAR-CISA))
Gear budgetRanges in euros for a 2-person household at typical prices in Spanish stores; they vary with brand and deals (Preparados72h estimate, November 2026)
Battery and solar panelBattery = daily use × days ÷ 0.85 (usable share). Panel = daily use ÷ (peak sun hours × 0.75). Peak sun hours in Spain: about 2.5 in winter, 4.5 in spring and autumn and 6 in summer; fewer in northern Europe (Preparados72h calculation using PVGIS irradiation data (European Commission Joint Research Centre))
Our own criteriaMedication for the time frame plus 7 days; 7 diapers a day; 110 g of formula a day; 1 roll of toilet paper every 3 days per person; batteries and flashlights (Preparados72h estimates: adjust them to your situation)

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