Caloric Budget for a Community
Feeding 30 to 150 people year-round is fundamentally different from feeding a family. Mistakes in planning mean starvation in February. This guide provides the math and methods to calculate exactly how much land, labor, and livestock your community needs.
Understanding Community Caloric Demand
The first step is knowing how many calories your community actually needs. This is not a single number — it shifts with seasons, demographics, and work intensity.
Baseline Adult Requirements
A sedentary adult needs roughly 2,000 calories per day. In a post-collapse community, almost nobody is sedentary. Use these working figures:
- Light labor (cooking, childcare, administration): 2,200-2,400 kcal/day
- Moderate labor (gardening, animal care, crafting): 2,600-3,000 kcal/day
- Heavy labor (plowing, logging, construction, blacksmithing): 3,500-4,500 kcal/day
During peak agricultural seasons (planting in spring, harvest in fall), most adults shift into heavy labor for 4-8 weeks. Your caloric budget must account for these spikes.
Demographic Adjustments
For a community of 100 people, a realistic demographic breakdown might be:
- Children under 10: 15-20 people, needing 1,200-1,800 kcal/day
- Adolescents 10-17: 10-15 people, needing 2,200-3,200 kcal/day (growth + labor)
- Working adults 18-60: 50-60 people, needing 2,600-4,000 kcal/day
- Elderly/disabled: 10-15 people, needing 1,800-2,200 kcal/day
- Pregnant/nursing women: 3-8 at any time, add 300-500 kcal/day above baseline
For planning purposes, use 2,800 kcal/day as community average. For 100 people, that is 280,000 kcal/day or 102.2 million kcal/year.
Crop Calorie Yields
Not all crops are equal. Your acreage plan must prioritize calorie density.
Calorie Yield Per Acre (Realistic, Non-Industrial)
These figures assume hand labor or animal-powered cultivation, saved seed, no synthetic fertilizers, and moderate soil quality:
| Crop | Yield (lbs/acre) | Calories/lb | Calories/acre |
|---|---|---|---|
| Potatoes | 8,000-15,000 | 350 | 2.8-5.25M |
| Sweet potatoes | 6,000-12,000 | 390 | 2.3-4.7M |
| Corn (grain) | 1,500-3,000 | 1,650 | 2.5-5.0M |
| Wheat | 800-1,500 | 1,520 | 1.2-2.3M |
| Oats | 700-1,200 | 1,740 | 1.2-2.1M |
| Dry beans | 600-1,200 | 1,520 | 0.9-1.8M |
| Sunflower (oil) | 500-1,000 | 2,620 | 1.3-2.6M |
| Cabbage | 10,000-20,000 | 110 | 1.1-2.2M |
| Squash (winter) | 5,000-12,000 | 180 | 0.9-2.2M |
Key insight: Potatoes and corn are your caloric workhorses. Wheat is essential for bread but yields fewer calories per acre. A mixed strategy is mandatory — monoculture invites catastrophic failure.
The Basic Formula
For a community of N people:
Total acres needed = (N × 2,800 × 365) / average calories per acre
Using a diversified crop plan averaging 2.5 million calories per acre:
- 30 people: ~12 acres of cropland
- 50 people: ~20 acres
- 100 people: ~41 acres
- 150 people: ~61 acres
But double it. You need a 100% buffer for:
- Crop failure (drought, disease, pests)
- Seed saving (10-15% of harvest reserved)
- Fallow rotation (25-33% of land resting each year)
- Animal feed crops
Realistic planning: 1 to 1.5 acres of total agricultural land per person.
Livestock Feed Conversion
Animals convert plant calories into meat, dairy, and eggs — but always at a loss. The question is whether that loss is worth the nutritional diversity.
Feed Conversion Ratios
| Animal | Feed:Meat Ratio | Calories In → Calories Out | Best Use |
|---|---|---|---|
| Chickens (eggs) | 2.5:1 | 20-25% efficient | Best animal calorie converter |
| Chickens (meat) | 3:1 | 15-20% efficient | Fast protein |
| Goats (dairy) | 4:1 | 15-20% efficient | Browse marginal land |
| Pigs | 5:1 | 10-15% efficient | Eat scraps, waste |
| Cattle (dairy) | 6:1 | 12-18% efficient | Pasture-only possible |
| Cattle (beef) | 8:1 | 5-10% efficient | Only on land unsuitable for crops |
| Rabbits | 3.5:1 | 15-20% efficient | Fast breeding, small space |
Smart Livestock Strategy
Prioritize animals that eat what humans cannot:
- Goats and cattle on pasture, woodlot browse, and crop residues
- Pigs on kitchen scraps, whey, fallen fruit, and forest mast
- Chickens on insects, weeds, and grain screenings
- Rabbits on grass, weeds, and garden trimmings
Dedicate at most 10-15% of cropland to animal feed grain. The rest of animal nutrition should come from land unsuitable for crops (steep hillsides, woodlots, marshes).
For 100 people, a reasonable livestock count:
- 40-60 laying hens (15-20 eggs/day)
- 2-4 dairy goats or 1-2 dairy cows
- 4-8 breeding pigs
- 20-30 rabbits (breeding colony)
- Meat chickens raised in seasonal batches
Seasonal Planning
The Winter Gap
The critical vulnerability in any temperate-climate community is November through March. No fresh crops are growing (unless you implement four-season techniques). All calories during this period come from:
- Stored root crops: potatoes, turnips, carrots, beets in root cellars
- Dried grains and beans: properly stored wheat, corn, oats, dry beans
- Preserved foods: canned goods, smoked and cured meats, fermented vegetables
- Dairy: if animals are milked through winter (requires hay/silage)
- Eggs: reduced but still available with adequate light supplementation
Your caloric budget must ensure that at least 5 months of calories are stored and preserved before the first frost. For 100 people, that is roughly 42 million calories in storage.
Monthly Calorie Source Breakdown (Temperate Climate)
- April-May: Early greens, stored crops dwindling, dairy ramping up
- June-July: Fresh vegetables abundant, first grain harvest possible
- August-September: Peak harvest — potatoes, corn, beans, squash
- October-November: Late harvest, root crops, preservation marathon
- December-March: 100% stored/preserved food, supplemented by eggs and dairy
Putting It Together: Sample Plan for 100 People
| Category | Acres | Primary Crops |
|---|---|---|
| Staple grains | 25-30 | Wheat, corn, oats |
| Root crops | 10-15 | Potatoes, sweet potatoes, turnips |
| Legumes | 8-10 | Dry beans, peas, lentils |
| Oil crops | 3-5 | Sunflower, rapeseed |
| Vegetables | 5-8 | Cabbage, squash, onions, greens |
| Pasture/hay | 20-30 | Mixed grass for livestock |
| Fallow/rotation | 15-20 | Resting land, cover crops |
| Food forest | 5-10 | Fruit trees, nuts, berries |
| Total | 91-128 |
This gives roughly 1 to 1.3 acres per person — within the historical norm for pre-industrial subsistence communities.
Critical Safety Margins
- Always plant 20% more than calculations suggest
- Keep one year of emergency grain in sealed storage if possible
- Diversify: no single crop should represent more than 30% of total calories
- Track actual yields and adjust annually — your soil, climate, and skills will differ from any table
The caloric budget is not a one-time calculation. It is a living document updated after every harvest, adjusted for population changes, and stress-tested against the worst season you have experienced so far.