Is a 1.5-Ton R-32 AC Big Enough for Your Home? Sizing Tips Mike Swears By

When you’re replacing or upgrading your cooling system, choosing the right tonnage matters just as much as choosing the right brand, refrigerant, or efficiency rating. And in 2025, with homeowners steadily shifting toward R-32 refrigerant systems, the 1.5-ton size is suddenly in the spotlight.

But here’s the Mike version of the truth:
A 1.5-ton R-32 AC is absolutely perfect for some homes and a huge mistake for others.

I’ve walked into too many houses where someone bought a system based purely on square footage, or because a neighbor swore “1.5 tons worked great for me.” Cooling load isn’t one-size-fits-all. Two homes with the same square footage can have completely different tonnage needs depending on climate, insulation, layout, sun load, ceiling height, ductwork, and more.

So today, you’re going to get the straightforward, experienced breakdown — no fluff, no sales pitch — on whether 1.5 tons is enough for YOUR home, and what homeowners consistently overlook when sizing a system.

Let’s get into it.

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What a 1.5-Ton AC Really Means

In HVAC, “tonnage” is a measurement of cooling capacity — not weight.

• 1 ton = 12,000 BTUs

• 1.5 tons = 18,000 BTUs

On paper, a 1.5-ton air conditioner removes 18,000 BTUs of heat per hour.

But in the real world?
A 1.5-ton AC only delivers that full capacity if your home conditions allow it.

You lose cooling power when:

• Ducts leak

• Sun exposure is extreme

• Windows are inefficient

• Attic insulation is poor

• Rooms have high ceilings

• Humidity is high

• Layouts are open

• Airflow is restricted

That’s why BTUs alone don’t determine whether 1.5 tons is right for you. Textbook numbers never tell the full story — real-world heat load does.

To understand how BTUs are calculated, the U.S. Department of Energy provides detailed guidance on cooling capacity fundamentals.

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Why R-32 Refrigerant Changes Performance Expectations

R-32 is a major step up from R-410A, not just in environmental impact but in actual cooling performance. If you're shopping for a 1.5-ton system in 2025 or later, you’re almost guaranteed to run into R-32 models.

Here’s why that matters for sizing.

Higher Heat Transfer Efficiency

R-32 absorbs heat more efficiently than R-410A, meaning you get more cooling output from the same tonnage.

Better High-Temperature Stability

R-410A loses noticeable performance when outdoor temps exceed 95°F.
R-32 holds its cooling capacity better in extreme conditions.

The ASHRAE refrigerant performance tables outline these efficiency differences clearly.

Lower Discharge Temperature

Cooler compressor operation = less wear and more stable cooling.

Lower GWP (Global Warming Potential)

Not a performance factor, but part of why R-32 is the long-term replacement for R-410A.

The EPA provides full refrigerant comparisons and safety guidelines for R-32 systems.

In Simple Terms:

A 1.5-ton R-32 system performs more like a strong 1.5-ton AC, not a borderline one.
But it still can’t overcome a home with poor insulation or extreme heat load.

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Square Footage: A Starting Point, Not a Final Answer

If you’re reading this, you probably want to know:

“How many square feet can a 1.5-ton R-32 AC cool?”

Here’s the actual range that works in most cases:

So based on square footage alone:

✔ 1.5 tons is ideal for 550–850 sq ft
✔ Possible for up to 900 sq ft ONLY if your home is well insulated

But — and this is the part most homeowners miss — square footage is only the first step of the calculation. It tells you nothing about heat load.

If you want to see how professional load calculations work, the ACCA Manual J guidelines explain the entire process.

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When a 1.5-Ton R-32 AC Is an Excellent Choice

If your home checks these boxes, 1.5 tons is right in the sweet spot.

1. Your Home Is Between 600–850 Sq Ft

This is the perfect pairing for most standard layouts, especially single-story homes.

2. You Live in a Moderate Climate

Think states like:

• Ohio

• Pennsylvania

• Virginia

• Oregon

• Minnesota

• Wisconsin

Not scorching-hot climates and not extremely humid regions.

3. Your Insulation Is Reasonable

As a minimum:

• R-38 attic insulation

• R-19 wall insulation

• Double-pane windows

• Weather-sealed doors

If your insulation is below these levels, your actual tonnage needs increase.

The ENERGY STAR insulation guide is a reliable reference for recommended values.

4. Your Layout Is Traditional

Closed-off rooms cool more efficiently than open-concept layouts — fewer cubic feet to condition.

5. You Have Good Ductwork

Leaky ducts can reduce system capacity by 20–30%.

6. Your Windows Don’t Take Direct Afternoon Sun

A west-facing living room with big windows can add the cooling load of an entire extra room.

If all or most of these describe your home, a 1.5-ton R-32 system will cool efficiently, evenly, and reliably, even on peak summer days.

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When a 1.5-Ton System Is Absolutely Too Small

Here’s where you should move up to a 2-ton system without hesitation.

1. Your Home Is Over 900 Sq Ft

No exceptions.

2. You Live in a Hot Climate

States like:

• Florida

• Arizona

• Texas

• Nevada

• Louisiana

• Georgia

• Alabama

In these zones, reduce the square-foot capacity of any AC by 20–35%.

The NOAA Climate Zone Maps show exactly why heat load varies so drastically.

3. You Have an Open Floor Plan

If your living room, kitchen, and dining area share one open space, you’re cooling more volume, not just area.

4. You Have Poor Insulation

Low attic insulation or drafty windows = higher cooling load.

5. You Have Big South- or West-Facing Windows

These rooms absorb extreme radiant heat and need more tonnage.

6. You Want One System to Cool Two Floors

A 1.5-ton system can’t effectively cool multiple levels.

If two or more of these apply, a 1.5-ton unit will struggle every summer.

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How Layout, Cubic Footage & Airflow Affect Cooling Load

Homeowners think in “square feet,” but air conditioning works in “cubic feet.”
That means ceiling height matters — a lot.

Impact of Ceiling Height

• 8 ft ceilings → normal load

• 9–10 ft → increase load 10–15%

• Vaulted ceilings → increase load 20–35%

Open Concept Reduces AC Effectiveness

Open floor plans allow heat from appliances, people, and sunlight to spread freely.

A 1.5-ton AC that cools 800 sq ft in a traditional home might only cool 600 sq ft in an open layout.

Long or Narrow Homes Need More Airflow

Shotgun-style or ranch layouts often need higher airflow and sometimes more tonnage.

Duct Sizing Matters

Undersized ducts choke airflow, reducing delivered BTUs.

The AHRI duct and airflow guidelines emphasize how ductwork impacts capacity.

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Windows, Sun Exposure & Heat Gain

Windows are the biggest source of hidden heat load. You’ll often need more tonnage not because your home is big — but because your windows act like magnifying lenses for the sun.

South- and West-Facing Rooms

These rooms take the hardest heat load from afternoon sunlight.

Single-Pane Windows

These can double your cooling load compared to double-pane.

Large Glass Surfaces

If more than 15% of your wall surface is windows, size up.

Ways to Reduce Window Heat Load

• UV-blocking film

• Cellular shades

• Thermal curtains

• Exterior awnings

• Better window glazing

The Energy Saver Window Efficiency Guide covers strategies to reduce solar heat gain.

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Climate Zone: The Most Overlooked Sizing Factor

Cooling needs vary massively by region, even for the same floor plan.

Hot-Humid Zones (Florida, Gulf Coast)

High humidity = higher latent heat load
Undersized systems will run nonstop and still struggle to dehumidify.

Hot-Dry Zones (Phoenix, Las Vegas)

Extreme radiant heat demands higher tonnage.

Cold or Northern Zones

Homes in these areas often have better insulation and lower cooling load.

Coastal Zones

Salt air + humidity = higher latent load and faster coil corrosion.

The ACCA Manual J highlights climate correction factors used in professional sizing.

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Why R-32 Systems Perform Differently on Hot Days

R-410A tends to lose cooling capacity as outdoor temps rise. R-32 does not drop off nearly as fast.

Better High-Temp Performance

R-32 maintains better thermodynamic efficiency above 95°F.

Lower Compressor Stress

Lower discharge temperature improves longevity and keeps performance consistent.

Higher EER (Energy Efficiency Ratio)

EER matters more than SEER2 during extreme heat.

The EPA Efficiency Ratings Overview explains why different ratings apply to different performance conditions.

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Mistakes Homeowners Make When Choosing AC Size

Here are the patterns I see all the time — and why people end up uncomfortable even with a “new” AC.

1. Basing the decision only on square footage

This ignores ceiling height, windows, climate, and insulation — all critical factors.

2. Ignoring duct condition

Leaky ducts can steal 30% of your cooling power.

3. Oversizing out of fear

Oversizing causes:

• temperature swings

• high humidity

• short cycling

• mold risk

4. Trusting outdated rules of thumb

“1 ton per 600 sq ft” hasn’t been accurate for decades.

5. Not considering window heat load

West-facing windows alone can break a 1.5-ton system.

6. Forgetting about future remodeling

Removing a wall? Expect higher cooling load.

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Step-by-Step Method to Verify Whether 1.5 Tons Is Enough

This is the straightforward Mike-approved checklist.

Step 1: Measure the Actual Square Footage

Not what you think your home is — what it truly is.

Step 2: Note Ceiling Heights

If they’re above 8 ft, tonnage requirements increase.

Step 3: Evaluate Window Count & Orientation

More windows = more tonnage.

Step 4: Check Insulation Levels

Especially the attic — where most heat enters.

Step 5: Inspect Ductwork

Look for leaks, kinks, undersized runs.

Step 6: Review Your Layout

Traditional → more efficient
Open concept → higher load

Step 7: Consider Your Climate Zone

This is one of the biggest factors affecting AC capacity.

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Final Verdict: Is a 1.5-Ton R-32 AC Enough for Your Home?

Here’s the direct answer:

YES — A 1.5-Ton R-32 AC Is Enough If:

• Your home is 600–850 sq ft

• You live in a moderate climate

• Your insulation is decent

• Your windows don’t face extreme sun

• Your layout is traditional

• Your ductwork isn’t leaking

• You’re cooling one floor

NO — A 1.5-Ton R-32 AC Is NOT Enough If:

• Your home is 900+ sq ft

• You live in a hot/humid climate

• Your layout is open concept

• You have poor insulation

• You have big west/south-facing windows

• You need to cool two levels

When in doubt, remember:

A perfectly sized AC always performs better than an oversized or undersized one — even if tonnage seems small on paper.

In the next blog, Mike will compare the R-32 and R-410A systems.