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Air Conditioner BTU Per Square Foot Calculator

Built by Kevin Glover · @gloverbuilds · Verified formula

The right AC size for any room — accounting for modern insulation.

📅 Updated April 2026 ✅ Formula verified 📖 4 min read 🆓 Free · No sign-up

In this article

How to size an AC
Bigger isn't better
Energy efficiency

Regra geral: 600 BTUs/m² em clima ameno, 800-1.000 em regiões quentes (Nordeste, Norte, Centro-Oeste). Ajuste: +10% se cozinha/sala aberta, +15% se muita exposição solar. Inverter economiza 30-50% na conta de luz vs convencional.

Selo Procel A ou A+ indica maior eficiência energética.

⚡ CalcWolf Insight

An oversized AC unit is worse than undersized. It short-cycles, wastes energy, increases wear, and fails to properly dehumidify the air.

Frequently asked questions

Como calcular BTUs?▾

Área (m²) × 600 (ameno) ou 800 (quente). Quarto 15m² em SP: 15×600 = 9.000 BTUs. No Nordeste: 15×800 = 12.000.

Inverter ou convencional?▾

Inverter: 20-40% mais caro, mas economiza 30-50% na luz. Se usar 4h+/dia, se paga em 18-36 meses.

Consumo mensal?▾

9.000 BTUs convencional: ~R$211/mês (8h/dia). Inverter equivalente: ~R$144-192/mês.

Ar de janela vale?▾

Para orçamento menor: R$1.000-1.800 vs R$1.800-3.500 do split. Mais barulhento e menos eficiente.

✓ Math logic verified against primary sources → See our verification process

Kevin Glover · @gloverbuilds

Founder, CalcWolf · GLVTS · Blickr

All formulas sourced from primary references — IRS publications, peer-reviewed research, and official standards. Results are tested against independent reference calculators before publishing. Rates and brackets updated when official sources change. Editorial policy →