Method and sources
How we estimate a three-month reserve
Every number on this site comes from four planning rates: one is an official water baseline, and three are ours. This page shows the formula, the sources, the limits, and how to correct us.
It applies to the free calculator, the 3-month guide, and the emergency checklist. A planning estimate is not a government standard, a nutrition plan, or a price quote.
Quick answer
The formula: adult-equivalents = adults + children 7–17 + (children 0–6 × 0.5). Person-days = adult-equivalents × months × 30. Dry food = person-days × 1.5 lb. Water = people × months × 30 × 1 gallon. Budget = person-days × $3. Four adults for three months is 360 person-days, 540 lb of dry food, 360 gallons of water, and a $1,080 baseline.
The result is a planning floor for a shopping list and a weekly budget. It deliberately does not try to be a complete diet, a local price, or a storage plan.
The four planning rates
The calculator is simple because it is explicit. Each rate is visible in the output, so you can change one assumption without redoing the whole plan.
| Rate | Value | Where it comes from | Status |
|---|---|---|---|
| Days per month | 30 | Planning convention, not a calendar rule. | Ours |
| Dry food | 1.5 lb per person-day | Weight of shelf-stable staples only. Not a calorie or nutrition target. | Ours |
| Water | 1 gallon per person-day | Ready.gov baseline for drinking and basic sanitation. | Official baseline |
| Budget | $3 per person-day | National planning baseline for comparison, not a store price or a BLS quote. | Ours |
Why 30 days, 1.5 pounds, and $3
Calendar months are 28 to 31 days, so the calculator uses 30 as a convention and labels the horizon as a planning window. Three months is 90 days; six months is 180. If you need exact days, use the calculator as a starting point and replace 30 with the number you are planning for.
The 1.5 lb rate is the weight of dry staples: rice, oats, beans, lentils, pasta, flour, and cornmeal. It is not a calorie target and not a balanced diet. It exists so a household can compare one, three, six, and twelve months with one number, and so the shopping list has a measurable target. Canned, frozen, and fresh food carry water and packaging weight, so they are tracked separately rather than folded into this number.
The free calculator splits that 1.5 lb into six categories using a published home-storage table (per adult per year: 400 lb grains, 60 lb legumes, 60 lb sugar, 16 lb dry milk, 10 lb fats, 8 lb salt), normalised to 1.5 lb per person-day. It is a weight ratio, not a USDA nutrition basket. The paid plan uses USDA food plans and age/sex baskets; the free version stays a planning ratio. The calculator shows the split for your household.
The $3 rate is a national comparison baseline. It is close enough to make a weekly savings target meaningful, but it is not a BLS quote and not a store price. The guides use it to show a range and then tell you to replace it with the prices you actually pay. When the paid plan ships, the budget will be built from dated price observations rather than a flat rate.
The water line is the one official number: Ready.gov recommends at least one gallon per person per day for drinking and basic sanitation. That is a minimum for an emergency, not a promise that 90 gallons per person is enough for every climate, activity level, pregnancy, illness, or pet. Treat it as a floor and raise it for your household.
Several published plans use category-level targets, including the Church of Jesus Christ of Latter-day Saints’ home storage guidance and CDC preparedness lists. We use one published home-storage ratio as a cross-check for the free split; we do not reproduce a full denominational or government basket. If your household follows a specific plan, use its numbers and treat ours as a cross-check.
What is counted, and what is not
The scope is narrow on purpose. A number that hides what it leaves out is worse than a smaller number with a label.
Counted
- Dry staples by weight, at 1.5 lb per adult-equivalent person-day.
- A six-category split of the dry weight for planning.
- A drinking and basic-sanitation water baseline, at 1 gallon per person per day.
- A budget baseline, at $3 per adult-equivalent person-day.
- Adult-equivalent person-days, so household size, children, and time horizon scale together.
Not counted
- Canned, frozen, fresh, and refrigerated food, and the power they depend on.
- Infant formula, pet food, guests, and medical or allergy-specific diets.
- Cooking fuel, a stove, containers, labels, and storage space.
- Local prices, sales tax, delivery, and spoilage or loss.
- Nutrition adequacy. The estimate measures weight and water, not calories or micronutrients.
The emergency food checklist adds the non-food items and the special needs groups. The 3-month guide adds the category list, the 13-week purchase pace, and the storage notes.
How the sources are checked
Each external source on a page carries the date it was checked. We re-open the source, confirm the specific sentence or table we rely on, and record the date. A source link is not a claim that the whole page agrees with us; the table says what the source establishes and how the page uses it.
| Source | What it establishes | How we use it | Checked |
|---|---|---|---|
| FEMA / Ready.gov — Water | At least one gallon of water per person per day for several days, for drinking and sanitation. | The water baseline. It is a floor, not a three-month guarantee. | |
| FEMA / Ready.gov — Food | At least a several-day supply of non-perishable food that needs no refrigeration or cooking. | The emergency minimum the longer reserve builds on. | |
| American Red Cross — Survival Kit Supplies | A 3-day supply for evacuation, a 2-week supply for home, and one gallon of water per person per day. | The 3-day and 2-week tiers on the checklist page. | |
| USDA CNPP Food Plans | Weekly food baskets and monthly costs by age and sex. | Reference for the food groups and budget in the full plan; not yet used to replace the flat rates. | |
| USDA FoodData Central | Calories and nutrients per 100 g, plus branded labels. | Checks calories and food groups when a plan moves beyond weight. | |
| FDA FoodKeeper / FoodSafety.gov | Storage times for 650+ foods plus cold-storage safety guidance. | First-eat and best-by prompts for the rotation sheet; cold-holding limits for outage content. | |
| Bluffdale, Utah — Estimated Basic Food Storage Needs | A published adult year-supply table for grains, legumes, fats, sugars, milk, and salt. | The six-category ratio in the free calculator; normalised to 1.5 lb per person-day. | |
| BLS Average Price Data | National average prices for selected food items and inflation context. | A reality check on the budget baseline; not the source of the $3 rate. |
Last updated:
Corrections and updates
The rates and sources are rechecked while a page is active. When a source changes, we update the page, the visible date, and the structured data date together. We do not silently move a number and keep the old date.
If a number looks wrong, email hello@householdreserve.com with the page URL, the number, and the source you think is correct. We will check it, publish the correction if it holds, and credit the correction if you want to be named. A correction with a primary source is more useful than a complaint without one.
Who is behind Household Reserve
Household Reserve is an independent planning project for ordinary households with a house, a family, and a budget. It is not a government agency, a food brand, or a medical practice. The free calculator and guides are the public layer; the printable plan is the paid layer, and it is not for sale yet.
The editorial rule is simple: separate official data, platform data, estimates, and our own assumptions; put a date on every external fact; and do not use fear to sell a plan.