Swamp cooler size calculator
Enter your space and get the airflow (CFM) to look for. The tool shows the formula, compares real models from manufacturer brochures, and covers pads, exhaust area, water use, and humidity limits.
Elevation note (Albuquerque)
The Albuquerque Sunport sits at 5,354.9 ft (FAA airport data). Thinner air at that elevation can affect equipment. None of our sources publish an altitude correction for cooler sizing, so this calculator applies none. Phoenix says its airflow data come from tests run under AMCA Standard 210. Ask the manufacturer or an installer whether to adjust at your elevation.
Aspen pads vs. rigid media (CELdek-type)
Aspen (wood fiber) pads
- PNNL describes aspen coolers as about 70% effective.
- Used in multi-sided coolers: 4 pads on down-draft units, 3 on side-draft units (Champion and Phoenix sheets).
- Lower part cost; University of Arizona Extension suggests new pads each spring.
- Replace when torn, worn, or mildewed (PNNL).
Rigid media (8" or 12")
- Phoenix lists saturation efficiency of 80% for 8", 89% for 12", and 93% for its Pro 4x4 media. PNNL says 12" media can be 90% or better.
- MasterCool says its media has a "standard life of 5 years," and may need replacing sooner where water has very high mineral content.
- MasterCool claims its rigid media cools indoor temperatures up to 8°F more than aspen. That is a manufacturer claim.
- Fits only coolers built for it (single-inlet units); you can't drop it into an aspen cooler.
- PNM's 2026 rebate covers large units with 12" rigid media; 8" units don't qualify (check current PNM terms).
Sources: PNNL, Phoenix AeroCool brochure, MasterCool manual, MasterCool media chart, UA Extension.
Estimate supply-air temperature
PNNL's method: supply temperature ≈ dry-bulb − effectiveness × (dry-bulb − wet-bulb). PNNL's example: 105°F dry-bulb and 60°F wet-bulb with 90% media gives 105 − (45 × 0.9) = 64.5°F. If you don't know the wet-bulb temperature, the NWS wet-bulb calculator can find it from temperature, humidity, and station pressure.
Real units can differ from this estimate because of airflow speed, pad condition, and duct heat gain.
Buy pads or media
Product links (plain links, no affiliate tracking yet)
Match your pad size with the pad finder first. Then compare: aspen cooler pads on Amazon · Champion parts store · MasterCool parts store
Rigid media (plain links)
Rigid cooler media on Amazon · MasterCool 12" universal media
Guides
- What size swamp cooler do I need? 7 checks before you buy
- How often to replace swamp cooler pads: 6 signs it's time
- Swamp cooler start-up: an 8-step spring checklist
Common questions
How do I calculate swamp cooler CFM?
Multiply floor area by ceiling height to get cubic feet, multiply by the air changes per hour (ACH) for your climate, and divide by 60. The PNNL / DOE Building America Solution Center gives the formula as Cooler size CFM = (CU FT × ACH) ÷ 60 and says most manufacturers suggest 20 to 40 air changes per hour.
What ACH should I use in Albuquerque?
On the air-change zone map in the PNNL guide, Albuquerque and most of New Mexico fall in the 30 ACH zone. The map is coarse, so this calculator also shows the 20–40 ACH range.
Why is the CFM on the box higher than the airflow I get?
Big numbers like 4800 or 6500 are usually an Industry Standard Rating. Phoenix Manufacturing describes it as a numeric index for comparing units from different manufacturers. Delivered airflow drops as static pressure from ducts rises, so this tool compares models by the CFM their brochures list at 0.0 or 0.3 inches of static pressure.
How big should the exhaust opening be?
The PNNL guide (citing PG&E) recommends about 2 square feet of unrestricted relief area per 1,000 CFM. Screens and louvers reduce the free area.
Do swamp coolers work during the monsoon?
They work less well when humidity is high. In PNNL's examples, 100°F air at 10% relative humidity comes out near 73°F, while 95°F air at 50% relative humidity comes out near 84°F. NWS Albuquerque's monsoon season runs June 15 through September 30.
Sources
- PNNL / U.S. DOE Building America Solution Center, “Evaporative Cooling Systems”: CFM formula, 20–40 ACH, ACH zone map (Fig. 8), effectiveness method, 2 sq ft per 1,000 CFM relief (citing PG&E), water use (citing SWEEP 2007), maintenance.
- Phoenix Manufacturing, Frigiking Residential Brochure: delivered CFM by static pressure, pad sizes, window cooler area ratings.
- Phoenix Manufacturing, AeroCool Residential Brochure: rigid media CFM, saturation efficiency, Industry Standard Rating definition.
- Champion Cooler brochure CBGB 01/23: down- and side-discharge CFM by static pressure.
- MasterCool ADA51/71 owner's manual: media life, relief opening, bleed-off, seasonal steps.
- MasterCool Universal Rigid Media chart: media depth, CFM class, saturation, fit list.
- University of Arizona Cooperative Extension, Cochise County Water Wise: water use per day, operating tips.
- NWS Albuquerque, monsoon awareness: June 15 – September 30 season.
- FAA NFDC airport data, ABQ: Sunport elevation 5,354.9 ft.
- PNM evaporative cooling rebates: 2026 rebate terms (updated July 23, 2026).
- U.S. DOE Energy Saver Guide (2022): evaporative coolers "work well in climates where the air is hot and humidity is low."
All sources were read on October 30, 2026. Manufacturer data can change, so check your model's current documents.
Disclosure: Leads Merchant LLC may add affiliate links to this page later. If you buy through one, we may earn a commission at no extra cost to you. Right now, product links go to plain searches or manufacturer pages. Read the full disclosure.