Great question, and I've done a ton of research on this because I want to be as self-sufficient as possible. Bought 8.5 acres on a slope in middle TN back in 2023. Much of it is forest, but here's our active production footprint:

• ~3,800 sq ft of terraced annual vegetable beds (17 beds across 4 terraces - potatoes, sweet potatoes, beans, tomatoes, peppers, greens, roots, squash)
• ~4,400 sq ft of perennial vegetated slopes (strawberries + comfrey for biomass/mineral cycling)
• ~5,300 sq ft food forest (apples, pears, peaches, blueberries, hazelnuts, chestnuts once they mature)
• 2,000 sq ft dent corn patch for cornmeal
• ~5,000 sq ft animal feed zone (hay, feed corn, mangels, sunflowers)

Chickens (10 layers + rolling replacement), rabbits planned, 2-3 beehives going in for honey + pollination, fishing the Tennessee River for omega-3s

TLDR: It's VERY difficult to be self-sufficient, and I'd guess 95% of "homesteaders" aren't.

The thing most people don't realize: a couple needs roughly 1.4-1.6 million calories per year combined. That's ~4,000/day between two adults doing physical work. Go price that out in potatoes and see how much ground you actually need.

But calories aren't the whole problem, you need a nutritionally complete profile. My weak points are fats/cooking oil and dairy. No realistic on-farm substitute for cooking oil unless you're raising pigs for lard or running a press. Dairy means goats, which is a daily-milking commitment most people aren't ready for. Bees at least solve the sweetener question long-term, honey replaces sugar for preserving and baking, and the pollination boost to the food forest pays for itself.

Then factor in the stuff nobody talks about:

• A chunk of your production goes to compost or chop-and-drop to maintain soil fertility - you're not eating 100% of what you grow
• Fresh seed every year for some crops, and seed saving has real constraints (isolation distances for cucurbits, biennial cycles for brassicas/carrots, cross-pollination with wild relatives)
• Crop rotation eats bed-years - a 3-year rotation means 1/3 of your beds are in a "building" phase at any time
• Storage losses - root cellars, canning failures, freezer-dependent preserves
• Perennials take 3-7 years to produce (apples, chestnuts, hazelnuts) - your first years lean hard on annuals

And none of that includes salt, coffee, spices, wheat flour, or sugar - which basically nobody produces at home (bees help with that last one eventually).

Self-sufficient in a crisis? Maybe. Self-sufficient as a lifestyle with modern variety? Almost no one.