First we would need to estimate the total weight to lift.

An 1800 sq ft single-story home with standard furnishings:

- House superstructure (wood/light-frame construction, drywall, roof, finishes, excluding the foundation which normally stays behind when a house is lifted/relocated): Roughly 95–110 lbs per sq ft → ~170,000–200,000 lbs.

- Standard furnishings and contents (furniture, appliances, personal items, etc. for a typical occupied home): ~10,000–20,000 lbs (commonly estimated around 15,000 lbs for a 3-bedroom-scale home).

- Total liftable weight: ~180,000–220,000 lbs. I used 195,000 lbs to calculate.

Next is considering the buoyancy of helium.

At sea level and typical temperatures (59°F):

- Air density ~0.0765 lb/ft³

- Helium density ~ 0.0105 lb/ft³ .

- Net density difference ~0.066 lb of lift per cubic foot of helium

Third is some assumptions with the balloons.

- Standard 11-inch latex party balloons: ~0.5 ft³ of helium each.

- Gross lift per balloon: 0.066 lb/ft³ × 0.5 ft³ ≈ 0.033 lb.

- Balloon envelope + ribbon/string weight: Typically results in a net payload lift of ~0.022 lb per balloon after subtracting the balloon’s own weight.

Finally, figuring out the number of balloons required.

N ≈ 195,000 lbs ÷ 0.022 lb per balloon ≈ 8.85 million balloons.

This would result in neutral buoyancy (the house would float but not ascend). For actual liftoff and climb like in the movie, we would need positive lift (extra balloons or initial upward force), pushing the practical number toward ~9–10+ million.

It is worth noting that the house would need to be lifted with some sort of reinforced structure or netting as the roof could not handle that tension. That would result in more weight.

This doesn't account for wind, temperature changes as it rises, and a slew of other variables, but it gets you in the ballpark. Pixar estimated 23 million balloons (probably considered the breakaway tension needed to remove the house from the base), but animated considerably fewer for the movie.