Dehumidifier Sizing Guide North Texas: Getting the Math Right (Because I Didn't at First)

Dehumidifier sizing in North Texas requires calculating moisture load, not just square footage—a 70-pint unit sized for 3,500 sq ft may be undersized if you have a pool, basement, or high-occupancy household. The formula: Base capacity (0.02 pints/sq ft) + moisture sources (pool adds 50-100 pints/day, each shower adds 0.5 pints, basement adds 20-30%). For most 2,500-3,500 sq ft North Texas homes, 90-130 pint whole-house dehumidifiers are needed. Target indoor humidity: 45-50% year-round. Portable units ($200-$500) work for single rooms; whole-house systems ($1,500-$3,500) integrate with your HVAC.

I want to tell you about Mrs. Patterson. She called me three times in one week. Three. And each time she was more upset than the last. I’d just installed a $2,800 whole-house dehumidifier in her Frisco home, and the thing ran nonstop. Her windows fogged up every single morning. That stale, damp smell in the master bedroom? Still there.

Here’s what happened. I sized it off square footage. 3,500 square feet, so a 70-pint unit. The installation manual agreed with me. The online sizing calculator agreed with me. But I completely forgot about her pool. And the wet bar downstairs. And her four teenagers who apparently shower like they’re training for the Olympics. That poor unit never stood a chance.

It cost her another $1,200 to swap in a 130-pint system. And yeah, that came out of my credibility, not hers. But that week taught me something I still carry: dehumidifier sizing has nothing to do with following charts. You have to actually do the math for that specific house.

Emergency moisture issues? Call Jupitair HVAC at (940) 390-5676. We’ll size it right the first time.

The North Texas Humidity Problem Nobody Talks About

Everybody knows your AC pulls moisture out of the air. That’s not news. What nobody mentions is how North Texas humidity behaves in ways that don’t match what the textbooks say. I’ve seen afternoons where it was 42% at lunch and 78% by the time I sat down for dinner. The AC shut off because the house was cool enough. But meanwhile humidity just kept climbing. Slow, like you don’t notice until your pillowcase feels damp.

Spring is the tricky one. Mornings are cool enough that the AC barely kicks on. But Gulf moisture doesn’t care about your thermostat. By April, the temperature in your house feels fine but you’re sitting in 65% humidity. And mold? Mold grows at 72 degrees just as happily as it does at 85.

I measure humidity in dozens of homes every month. Plano, Frisco, McKinney, it’s the same pattern everywhere I go. Master bedrooms consistently run 5-8% higher than the rest of the house. Finished basements? Tack on another 10%. And that guest bathroom nobody ever uses? Basically a greenhouse at this point.

Here’s what doesn’t work: cranking your AC down to 66 hoping the moisture goes away. That just makes you cold AND broke. What you actually need is dedicated dehumidification that’s sized for your real moisture load. Not a number somebody pulled from a chart.

The Real Math Behind Dehumidifier Sizing

Throw out the simple sizing charts. They’re fine for houses in Ohio. Here’s what actually works in our climate.

Step 1: Baseline Calculation

• Measure your real square footage (not whatever the builder told you)
• Multiply by 0.02 for moderately damp conditions
• Multiply by 0.03 if it’s noticeably wet
• Multiply by 0.04 if you’ve got standing water or visible problems

Example: 2,800 sq ft home with a damp basement 2,800 x 0.03 = 84 pints/day baseline

Step 2: North Texas Adjustments Now you add in the moisture sources people forget about:

• Each person living there: +5 pints/day
• Each bathroom: +3 pints/day (double it if teenagers live in your house)
• Kitchen: +6 pints/day
• Laundry room: +4 pints/day
• Pool or hot tub: +15 pints/day
• Poor ventilation: +10 pints/day
• Crawl space: +20 pints/day

So that same 2,800 sq ft home:

• 4 people: +20 pints
• 3 bathrooms: +9 pints (one of those is the teenager’s, so it counts double)
• Kitchen: +6 pints
• Laundry: +4 pints Total adjustment: +39 pints

Step 3: Climate Factor We’re not Miami. But we’re sure not Phoenix either. Between March and October, add 20% to whatever number you’ve got.

84 + 39 = 123 pints 123 x 1.2 = 147.6 pints/day needed

Step 4: Safety Margin Add 15%. Manufacturers test their capacity numbers in lab conditions you’ll never replicate in a real house. They just do.

147.6 x 1.15 = 170 pints/day actual requirement

Now you see why that 70-pint unit couldn’t keep up at Mrs. Patterson’s.

Whole-House vs Portable: Different Math, Different Mistakes

Whole-House Dehumidifiers

These tie into your existing HVAC system, which means they work even when your AC isn’t running. That’s the whole point. But sizing them means looking at both your moisture load AND whether your ductwork can handle the extra airflow.

Formula for whole-house: CFM needed = (Pints per day x 2.5) / 60

Using our example: (170 x 2.5) / 60 = 7.1 CFM minimum

Here’s the thing people skip though. Your ducts might not be up to it. I’ve worked on plenty of 3-ton systems where the return ducts were undersized from day one. The system can’t pull enough air through for the dehumidifier to do its job. You need a static pressure test before anything else gets installed. I learned that one the expensive way too.

Price reality check:

• 70-pint unit: $1,800-2,200 installed
• 100-pint unit: $2,400-2,800 installed
• 130-pint unit: $2,900-3,500 installed

Portable Dehumidifiers

Totally different situation. These handle one room or one zone. The math works differently:

Room volume x Air changes per hour x Moisture difference = Pints needed

Master bedroom example:

• 15’ x 18’ x 9’ ceilings = 2,430 cubic feet
• 4 air changes per hour for bedrooms
• 65% current humidity, 45% target = 20% reduction needed

(2,430 x 4 x 0.20) / 13.5 = 144 pints/day

Yeah, for one room. A 70-pint portable realistically covers about 1,000 square feet. Start running two or three of them and your electric bill gets ugly fast.

Portable costs:

• 35-pint: $200-300
• 50-pint: $300-450
• 70-pint: $450-650

The Expensive Mistakes I See Every Week

Undersizing Because “It’s Not That Humid”

Had a call in Allen last month. Guy bought a 50-pint unit for his 2,200 sq ft home because, his words, “we only really notice it in spring.” I pulled out my meter in the utility closet. 71%. That undersized unit was running around the clock, actually pulling maybe 30 pints in real-world conditions, and his electric bill was up $80 a month. He still had moisture problems. Fifty bucks says there’s mold behind that closet drywall too, but he didn’t want to hear that.

Oversizing to “Be Safe”

This one burns me just as much. Homeowner in Prosper put a 150-pint whole-house unit in a tight 1,800 sq ft home. Way too much capacity. It short-cycled constantly, never ran long enough to actually move air through the house properly. Cold spots here, warm spots there, and he spent an extra $1,000 he didn’t need to.

Ignoring Duct Limitations

This happened just last week in McKinney. Customer bought the dehumidifier himself online. Good unit, right capacity for his house. But his 30-year-old ductwork couldn’t handle the additional airflow. The whole system struggled. Had to resize his return ducts before the dehumidifier could even function. That was another $1,800 he wasn’t expecting.

The Basement Special

“Oh, it’s just for the basement.” I hear that one all the time. Somebody sticks a portable in a 1,500 sq ft basement and waits for a miracle. What actually happens is that moisture travels upstairs. Now you’ve got one overworked portable trying to dehumidify the whole house through the stairwell. That’s not how air works. Never has been.

Integration With Your Existing AC System

Your AC and your dehumidifier need to work together, not against each other. And most people don’t realize they’re sometimes fighting.

Here’s the classic trap. Thermostat’s set to 72, humidity starts climbing, so you drop it to 68 hoping the extra cooling removes moisture. Now you’re shivering in your own living room and your electric bill is through the roof. Oh, and your AC coil might freeze up from running that cold for that long. I’ve seen it happen more times than I can count.

What you want instead:

1. AC handles temperature
2. Dehumidifier handles moisture
3. Neither one works overtime

I was at a house in Frisco last Tuesday where they had this completely backwards. AC cranked down to 68 trying to wring moisture out of the air. Dehumidifier running full blast but all that cold air just made everything feel clammy. I adjusted the balance. Set the AC back to 74, let the dehumidifier handle the moisture on its own. Their monthly bill dropped $120. Same comfort level. Actually better.

Variable-speed systems help a lot with this because they run longer at lower speeds, pulling more moisture without freezing you out. But even a nice variable-speed system gets humbled by North Texas in April. Don’t kid yourself. A maintenance plan helps catch humidity issues before they turn into mold problems.

Seasonal Sizing Adjustments

Humidity here isn’t one number year-round. It swings. And your sizing needs to account for the swings. March through May is the worst stretch by far.

Spring (65-75% outdoor humidity)

• You need full capacity. No question.
• Focus on bedrooms and bathrooms first
• If your windows are fogging up in the morning, you’re already behind

Summer (55-70% outdoor humidity)

• Your AC picks up more of the slack
• You can dial back the dehumidifier runtime by about 30%
• Concentrate on zones where the AC doesn’t reach well

Fall (50-65% outdoor humidity)

• Use it when you need it, mostly evenings and mornings
• Basement and crawl space are the priority
• Some weeks you won’t need it at all

Winter (45-60% outdoor humidity)

• Barely any use
• Maybe run it in known problem spots
• Be careful not to overdo it. Too dry and you’ll get cracked wood floors and static everywhere

My advice: size for spring, adjust down for summer. I’d rather you have capacity sitting idle in August than mold colonies setting up shop in April.

The Money Reality

Let’s just look at what this costs around here, no sugarcoating.

Going the Portable Route:

• 3 units to cover an average-sized home: $900-1,500
• Electricity: $40-60/month during peak season
• They last about 3-5 years before replacement
• Total 5-year cost: roughly $4,500

Going Whole-House:

• Professional installation: $2,400-3,500
• Electricity: $25-35/month during peak season
• Lasts 10-15 years with proper maintenance
• Total 5-year cost: roughly $3,900

The numbers favor whole-house if you’re staying in your home. But I’ve watched people spend $3,500 on a system and then move two years later. Expensive way to improve somebody else’s house.

My Sizing Cheat Sheet

I’ve been keeping notes on every install for years now. After 500+ of them, here’s where I land for typical Frisco and Plano homes:

Frisco/Plano typical homes:

• 1,500-2,000 sq ft: 70-90 pints
• 2,000-2,500 sq ft: 90-110 pints
• 2,500-3,000 sq ft: 110-130 pints
• 3,000-4,000 sq ft: 130-155 pints
• 4,000+ sq ft: 155+ pints (probably need two units at that point)

Add 20% for:

• Pool or spa
• Finished basement
• Poor ventilation
• 5+ people in the house
• Home built before 2000

Subtract 10% for:

• Spray foam insulation
• Newer windows and doors
• Variable-speed HVAC system
• Not much cooking happening
• Empty nesters

The Installation Reality Check

Getting the size right doesn’t matter if the installation is sloppy. Here’s what I end up fixing for other people.

Drainage disasters. Went to a place in The Colony last month. The dehumidifier was draining into a crawl space. Just dumping water right back where it came from. Customer couldn’t figure out why nothing was improving. Because the unit was working perfectly, just recycling the same moisture in a loop.

Location mistakes. Portable unit crammed in a corner behind a couch and a bookshelf. You need at least 12 inches of clearance on all sides for these things to breathe. Putting one behind furniture is basically donating to TXU.

Ductwork problems. Whole-house unit bolted in without anyone checking static pressure first. System can’t move enough air, efficiency drops, and the equipment dies years early.

Control settings gone wrong. Dehumidistat set to some wild target. Had a house in McKinney where someone programmed the dehumidifier to hit 35% humidity. In Texas. In July. That’s desert air. Their hardwood floors started cracking within two months. You want 45-50%. That’s it.

Red Flags You’re Sized Wrong

If you’re living with equipment that doesn’t fit your house, you’ll recognize these.

Undersized symptoms:

• Runs all day and all night, humidity stays high anyway
• That musty smell that just won’t go away
• Condensation on windows, especially in the morning
• Mold showing up in bathrooms or closets
• Reservoir fills up constantly but nothing improves

Oversized symptoms:

• Short cycles, runs maybe 5-10 minutes then shuts off
• Humidity readings bounce around all over the place
• Some rooms feel too dry while others stay damp
• Electric bills higher than you’d expect
• Noticeable temperature drop when the unit kicks on

Need professional sizing? Call Jupitair HVAC at (940) 390-5676. We measure everything, calculate for your specific house, and guarantee results.

The Bottom Line Math

I lost money on Mrs. Patterson’s job. But I gained something I use every single day since then: the understanding that sizing isn’t about rules of thumb. It’s about measuring the house in front of you, doing the math, and adjusting for the stuff the charts can’t see.

Your North Texas home isn’t a textbook example. It’s got its own quirks. Maybe that bonus room over the garage that stays sticky no matter what. Or the master bath where nobody ever installed an exhaust fan. Or the kid who treats every shower like a spa day. No sizing chart on the internet knows about any of that.

I carry a notebook in my truck now. Every installation gets an entry: what I calculated, what I actually installed, and what the readings look like three months later. The pattern is clear at this point. North Texas homes need 20-30% more dehumidification capacity than what the manufacturer charts recommend. Every single time.

Still running that old dehumidifier that came with the house? Still dropping your thermostat to 65 hoping the AC will handle the humidity? Think about what that’s actually costing you. The electricity. The discomfort. The mold you might not even see yet.

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Frequently Asked Questions

Q: What size dehumidifier do I need for my basement? A: Basement dehumidifier sizing depends on basement size, moisture conditions, and whether it’s finished or unfinished:

Basement Size	Moderately Damp	Very Damp/Wet	Extremely Wet
500 sq ft	30-40 pints	40-50 pints	50-60 pints
1,000 sq ft	40-50 pints	50-60 pints	60-70 pints
1,500 sq ft	50-60 pints	60-70 pints	70-90 pints
2,000 sq ft	60-70 pints	70-90 pints	90-110 pints

For North Texas specifically (rare basements, but they exist in some older homes and custom builds): Our clay soil creates unique moisture intrusion patterns. Add 20-30% to standard calculations. If you have foundation cracks, sump pump, or visible water seepage, go with the “extremely wet” column. Basements here also tend to be warmer than northern basements, which affects dehumidifier efficiency—units lose capacity in warmer air. Look for units rated for “high-temperature” operation (up to 95°F).

Q: What size dehumidifier do I need for 2000 sq ft? A: For a 2,000 sq ft whole-house dehumidifier in North Texas, you’ll need 70-100 pints per day capacity depending on moisture sources. A standalone 2,000 sq ft area (like a basement) with moderate dampness needs 60-70 pints. For a whole house, factor in: number of occupants (4+ people = add 10%), pets (add 5-10%), attached garage (add 10%), swimming pool (add 50-100 pints), and cooking/shower frequency. Most North Texas homes at 2,000 sq ft do well with a 90-pint whole-house unit integrated with the HVAC system.

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Sources & References

The dehumidifier sizing calculations, humidity control data, and health recommendations in this article are based on the following authoritative sources:

• U.S. Department of Energy - Dehumidifiers - Sizing guidelines and energy efficiency standards
• EPA Indoor Air Quality - Mold - Humidity control for mold prevention
• ENERGY STAR Dehumidifiers - High-efficiency dehumidifier specifications
• ASHRAE Humidity Guidelines - Recommended indoor humidity levels for comfort and health
• CDC Mold and Dampness - Health effects of high indoor humidity

Last Updated: January 2026