--- title: "What size AC do I need? A New Braunfels sizing guide" description: "Estimate the AC tonnage your New Braunfels home needs with a free calculator, see the square-footage rule of thumb, and why Manual J is the real answer." canonical: https://newbraunfelsacguide.com/costs/system-size/ source: https://newbraunfelsacguide.com/costs/system-size/ --- 1. [Home](https://newbraunfelsacguide.com/) 2. [Costs](https://newbraunfelsacguide.com/costs/) 3. System size System size # What size AC do you need? Get a quick tonnage estimate for your New Braunfels home below, then see the square-footage rule it's based on — and why the right answer ultimately comes from a load calculation, not a rule of thumb. Sizing estimate ### Estimate the AC size your home needs A quick rule-of-thumb starting point for New Braunfels homes. The real number comes from a load calculation — this tells you the ballpark to expect. Home size (sq ft) Ceilings Standard (8 ft) High (over 8 ft) Sun exposure Average Lots of sun / west-facing Heavily shaded People in the home Estimated size — Cooling capacity — Industry rule of thumb — about 25 BTU per square foot, adjusted for your ceiling, sun, and occupants. A starting estimate, not an [ANSI/ACCA Manual J](https://www.acca.org/standards/technical-manuals/manual-j) load calculation, which a licensed pro runs using your insulation, windows, orientation, and local design temperature. How this is estimated, and why a Manual J matters We start at roughly 25 BTU per square foot, add 10% for high ceilings, adjust ±10% for sun or shade, and add 600 BTU for each person beyond two — then divide by 12,000 to get tons (1 ton = 12,000 BTU/hr). It lines up with the common "about 500 square feet per ton" rule. This is deliberately a ballpark. A proper [Manual J load calculation](https://www.acca.org/standards/technical-manuals/manual-j) — the ANSI-recognized standard — accounts for your home's insulation, window area and orientation, air infiltration, and New Braunfels' design temperatures, which the square-footage rule can't see. Oversizing is a real risk: a system that's too big short-cycles, dehumidifies poorly, and wears out early, so the [U.S. Department of Energy](https://www.energy.gov/energysaver/central-air-conditioning) calls for a load calculation rather than guesswork. The rule of thumb ## How many tons of AC per square foot? The common starting point is about one ton How much cooling a system delivers (1 ton ≈ 12,000 BTU/hour). Bigger home, more tons — but bigger is not always better. [Full definition](/glossary/#tonnage) of cooling per 500–600 square feet, or roughly 25 BTU per square foot. This table shows where typical New Braunfels home sizes land before adjustments for ceilings, sun, and insulation. A rough ~500 sq ft per ton guide — a starting estimate, not a Manual J load calc. Square footage to AC tonnage (rule of thumb) Home size Approx. tonnage Cooling capacity 1,000 sq ft 2 tons 24,000–25,000 BTU/hr 1,200 sq ft 2.5 tons 30,000 BTU/hr 1,500 sq ft 3 tons 36,000–37,500 BTU/hr 2,000 sq ft 4 tons 48,000–50,000 BTU/hr 2,500 sq ft 5 tons 60,000–62,500 BTU/hr 3,000 sq ft 6 tons 72,000–75,000 BTU/hr A rule-of-thumb starting point only — newer, well-insulated homes often need less, older or sun-exposed homes more. Tonnage is also the biggest single driver of install price, so once you have an estimate, see how it maps to [replacement cost in New Braunfels](/guides/hvac-replacement-cost-new-braunfels/). The real answer ## Why a Manual J load calculation beats the rule of thumb A Manual J load calculation The room-by-room math (industry standard: ACCA Manual J) that sizes your system correctly instead of guessing. [Full definition](/glossary/#load-calculation) — the ANSI/ACCA standard — sizes your system from the things square footage can't capture: insulation, window area and orientation, air leakage, and New Braunfels' design temperatures. A contractor who runs one (rather than just matching your old unit) is sizing it properly. Oversizing isn't a safe default — it short-cycles, dehumidifies poorly, and shortens equipment life. Common questions ## AC sizing FAQs What size AC do I need for my home? As a rule of thumb, plan for about one ton of cooling per 500–600 square feet, or roughly 25 BTU per square foot — so a 2,000 sq ft home lands near 3.5–4 tons. Adjust up for high ceilings, heavy sun, or extra occupants. The calculator above gives a quick range; a Manual J load calculation gives the exact figure. [Source: U.S. DOE](https://www.energy.gov/energysaver/central-air-conditioning). Is a bigger AC unit better? No — an oversized system is a common, costly mistake. It cools the air fast and shuts off before it removes humidity, so it short-cycles, leaves hot and cold spots, runs up the bill, and wears out early. In a humid climate like New Braunfels, right-sizing matters more than going big. [Source: U.S. DOE](https://www.energy.gov/energysaver/central-air-conditioning). What is a Manual J load calculation? Manual J (the ANSI/ACCA standard) is the proper method a contractor uses to size your system. It accounts for square footage, insulation, window area and orientation, air leakage, and local design temperatures — the factors a simple square-footage rule can’t see. Ask any contractor whether they run one before quoting equipment. [Source: ACCA](https://www.acca.org/standards/technical-manuals/manual-j).