Texas BTU Calculator
Detailed heating and cooling load estimate sized for Texas heat. Pre-set for Zone 2 (hot) with Texas-friendly assumptions. Adjust for your city below. Most Texas homes need 18–25 BTU per sq ft for cooling — enter your room below for a precise number including attic duct losses and humidity.
Updated for 2026 SEER2 standards and Texas electricity rates.
On this page: Calculator · Texas climate zones · Texas HVAC tips · Winter heating · SEER & rates · Equipment guide · FAQ
Just need a quick estimate? The simple BTU calculator gives you an answer in 10 seconds. For the full US-default version, see the advanced BTU calculator.
Texas cooling rule of thumb
Many Texas rooms land around 18–25 BTUs per square foot for cooling, depending on sun exposure, ceiling height, window count, and insulation. If your space gets intense afternoon sun or has high ceilings, expect the higher end.
Heating loads in Texas are usually modest (often 25–40 BTU/sq ft), but North Texas and the Panhandle can need more in winter cold snaps.
This calculator is pre-configured for Texas (hot climate default) using the same underlying math as the main advanced tool. For a code-compliant whole-home load calculation, consult an HVAC contractor or use an ACCA Manual J tool. You can also get a free HVAC quote from local Texas contractors.
Texas climate zones (quick guide)
Texas spans multiple IECC climate zones. Picking the right zone helps avoid under-sizing in peak summer and over-sizing that short-cycles and struggles with humidity.
| Texas area | Example cities | Zone | Cooling note | Multiplier |
|---|---|---|---|---|
| Gulf Coast | Houston, Galveston, Corpus Christi | 2 | Hot + humid; humidity control matters | ×1.15 |
| South Texas | McAllen, Brownsville, Laredo | 2 | Long cooling season; strong sun load | ×1.15 |
| Central Texas | Austin, San Antonio | 2–3 | Hot summers; shading helps | ×1.10–1.15 |
| North Texas | Dallas, Fort Worth, Waco | 3 | Hot summers + occasional winter snaps | ×1.10 |
| West Texas | El Paso, Midland, Odessa | 3 | Drier heat; big day/night swings | ×1.10 |
| Panhandle | Amarillo, Lubbock | 3–4 | More heating demand than the rest of TX | ×1.00–1.10 |
If you're between zones, pick the warmer (lower number) for coastal/southern areas and the cooler (higher number) for the Panhandle and higher elevations.
Texas HVAC sizing tips
Shade & window gains
West-facing windows often drive peak load in Texas afternoons. If your room gets heavy sun, select “Heavy” sun exposure in the calculator. Consider window film, blinds, or exterior shade to reduce solar gain before oversizing your AC.
Attic + duct losses
Ducts in a 130°F+ Texas attic can waste 20–30% of your cooling. If your ducts are leaky or poorly insulated, choose “Poor” duct condition to avoid under-sizing. Better yet, seal and insulate the ducts — or consider a ductless mini split which eliminates duct loss entirely.
Humidity control
In humid regions (Houston, Gulf Coast), right-sizing helps the system run long enough to remove moisture. Oversizing can make the home feel clammy even when the thermostat reads “cool.” If humidity is a persistent problem, a dedicated dehumidifier can help. For newer, tighter Texas homes, an HRV or ERV provides controlled fresh air without adding humidity load.
Ceiling height
High ceilings increase air volume significantly. A 10 ft ceiling adds 25% more air than an 8 ft ceiling in the same footprint. Many newer Texas homes have 9–10 ft standard ceilings and 12+ ft great rooms — enter your actual ceiling height for an accurate result.
SEER rating for Texas
Texas’s long cooling season means higher-SEER equipment pays back faster. The federal minimum for the South region is SEER2 14.3, but SEER2 16–20 often pays for itself in 3–5 years through lower electricity bills. Compare specific ratings with the SEER savings calculator.
Low-cost upgrades that reduce BTUs in Texas
Weatherstripping ($5–15) stops hot air leaks at doors. Window insulation / film ($10–30) reduces solar gain through glass. Door sweeps ($8–20) seal gaps under exterior doors. Spray foam ($10–40) seals attic penetrations and rim joists.
A smart thermostat ($25–250) can reduce run time 10–15% by optimizing schedules. Verify savings with an energy monitor ($20–30). Find your local rate at ElectricityLocal.
Check for federal tax credits on heat pumps (up to $2,000), insulation, and smart thermostats.
Texas winter heating: sizing for cold snaps
Texas is primarily a cooling-dominated state, but the February 2021 winter storm demonstrated that heating capacity matters. Many Texas homes were under-heated because their systems were sized only for typical winters — not for sustained sub-freezing temperatures.
Heat pump performance in Texas winters
Standard heat pumps lose efficiency as outdoor temperatures drop. Below 35°F, a conventional heat pump may struggle to maintain indoor temperature without electric resistance backup strips. For North Texas, the Panhandle, and anywhere that regularly sees temperatures below 25°F, consider a cold-climate heat pump (rated to −13°F or lower) or a dual-fuel system (heat pump + gas backup). Use the heat pump calculator to size for your worst-case winter temperature, not just the average.
Backup heat and supplemental sizing
For Gulf Coast and South Texas homes that rarely see freezing temperatures, a 1,500W space heater (5,120 BTU) is often enough for supplemental warmth during rare cold days. For homes in North Texas or the Panhandle that experience regular winter freezes, size your primary heating system for at least 35–40 BTU per sq ft rather than the typical Texas 25–30 BTU/sq ft rule of thumb. Use the furnace size calculator for whole-home heating sizing.
| Texas region | Winter design temp | Heating BTU/sq ft | Recommended system |
|---|---|---|---|
| Gulf Coast (Houston, Corpus) | 28°F | 25–30 | Heat pump with backup strips |
| Central TX (Austin, San Antonio) | 22°F | 28–34 | Heat pump or gas furnace |
| North TX (DFW) | 15°F | 32–38 | Cold-climate heat pump or dual-fuel |
| Panhandle (Amarillo, Lubbock) | 5°F | 38–46 | Gas furnace or cold-climate heat pump |
Winter design temperatures above are 99% design values (the coldest 1% of hours per year). Sizing to this level ensures your system handles extreme events, not just average winters.
Texas electricity rates and SEER payback
Texas has a deregulated electricity market in most areas served by ERCOT (most of the state except El Paso and some border regions). This means rates vary significantly by provider, plan, and season — and choosing a higher-SEER system can have a faster or slower payback depending on your actual rate.
How SEER rating affects Texas operating costs
Texas averages roughly 2,500–3,000 cooling hours per year — about 2× the national average. This makes SEER upgrades pay back faster here than almost anywhere else in the US. A jump from SEER2 14.3 (federal minimum) to SEER2 18 on a 3-ton system can save $150–$250 per year in a typical Texas home. Use the SEER savings calculator with your actual BTU result and local rate for a precise payback estimate.
Time-of-use rates and smart thermostats
Many Texas electricity providers offer time-of-use (TOU) plans where peak-hour rates (typically 3–8 PM in summer) can be 3× the off-peak rate. A smart thermostat that pre-cools during off-peak hours and reduces runtime during peak hours can cut your summer electricity bill by 15–25% beyond the base SEER savings. Check ElectricityLocal for your current rate and plan options.
Equipment sizing guide for Texas
Texas sizing is primarily about cooling capacity and humidity management. Use your BTU result to match common equipment categories:
Cooling equipment
| BTU range | Equipment type | Texas context |
|---|---|---|
| 5,000–8,000 | Window AC or portable AC | Bedrooms, small offices |
| 8,000–14,000 | Portable AC or mini split | Living rooms, studios, sun-facing rooms |
| 14,000–36,000 | Mini split or central AC | Main floor zones, open-concept spaces |
| 36,000–60,000+ | Central AC / heat pump system | Whole-home sizing (confirm with Manual J) |
Cooling-specific calculators: AC size · Window AC · Portable AC · Mini split
Heating equipment
| BTU range | Equipment type | Texas context |
|---|---|---|
| Up to 5,200 | 1,500W space heater | Spot heat for small rooms |
| 5,200–24,000 | Heat pump or ductless mini split | Common in milder Texas winters |
| 24,000–75,000+ | Gas furnace or dual-fuel system | North TX / Panhandle cold snaps |
Heating-specific calculators: Furnace size · Heat pump · Space heater. All equipment by BTU: equipment guide.
Frequently asked questions
How many BTUs do I need for AC in Texas?
Many Texas rooms land around 18–25 BTUs per square foot for cooling. Homes with heavy sun exposure, high ceilings, lots of windows, or leaky attic ducts typically need more. Use the calculator above for a room-specific estimate (and tonnage).
What climate zone is Texas in?
Most of Texas is Zone 2–3, with the Panhandle and higher elevations often Zone 3–4. Use the Texas climate zone table on this page to choose the closest match.
Does humidity increase the BTU requirement in Texas?
Yes. Humidity increases cooling load because the system must remove moisture (latent heat) as well as reduce temperature. Proper sizing — not oversizing — is key to comfort in humid areas like the Gulf Coast. A dedicated dehumidifier can supplement in particularly humid rooms.
Should I oversize my air conditioner for Texas summers?
Usually no. Oversizing can short-cycle and reduce dehumidification, making the home feel sticky. For whole-home decisions, confirm sizing with a contractor using an ACCA Manual J calculation. You can also get a free HVAC quote from local contractors.
How do I convert BTUs to tons?
1 ton of cooling = 12,000 BTU/hr. For example, 24,000 BTU/hr is 2 tons, and 36,000 BTU/hr is 3 tons. This calculator shows tonnage when applicable. Use the AC size calculator for tonnage-specific central AC sizing.
What SEER rating should I buy in Texas?
The 2023 federal minimum for Texas is SEER2 14.3 for split systems. For Texas’s long cooling season, SEER2 16–20 often pays for itself in 3–5 years. Compare specific ratings with the SEER savings calculator. Check for federal tax credits on high-efficiency equipment.
What size AC do I need for a 2,000 sq ft Texas home?
A 2,000 sq ft Texas home in Zone 2–3 with average insulation typically needs 36,000–46,000 BTU (3–4 ton) for cooling. Homes with high ceilings, west-facing windows, or leaky attic ducts need the higher end. Use the calculator above for a room-specific estimate, or the AC size calculator for whole-home tonnage.
Should I size my heater for freeze events like February 2021?
For Gulf Coast and South Texas, a heat pump with backup strips handles most winters. For North Texas and the Panhandle, size to your 99% design temperature (roughly 5–15°F) rather than average winter temps. A cold-climate heat pump rated to −13°F or a dual-fuel system is the most resilient option for areas that experienced extended freezes. See the winter heating guide above and the heat pump calculator for sizing.
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