Air Purifier CADR Calculator - Find the Right Size (CFM/ACH)

🧮 Air Purifier Calculators - Find Your Perfect Match

Use our free calculators to determine the right air purifier size for your room (CADR/CFM), estimate energy costs, and calculate total cost of ownership. All calculations include metric conversions and real-world examples.

After calculating your needs, browse our comparison of 610 air purifiers →

📚 What is CADR and CFM?

CADR (Clean Air Delivery Rate): Measures how much clean air a purifier delivers per minute, in cubic feet per minute (CFM). Higher CADR = faster air cleaning.

CFM (Cubic Feet per Minute): Volume of air the purifier processes. CADR and CFM are the same measurement.

ACH (Air Changes per Hour): How many times the purifier cleans all the air in your room per hour. Higher ACH = cleaner air.

Formula: Required CFM = (Room Volume × ACH) ÷ 60 minutes

Use Metric Units (meters, m³/h)

Calculate Required CADR (Clean Air Delivery Rate)

Room Dimensions

Quick Presets:

Length (ft)

Width (ft)

Height (ft)

💡 Not sure? Standard ceiling height is 8 ft (2.4 m)

Air Quality Needs

What's your primary concern?

About ACH (Air Changes per Hour):
• ACH 2 = Basic air quality
• ACH 4 = Good for allergies/dust
• ACH 5 = Recommended for pets/smoke
• ACH 6 = Best for wildfire/severe issues

Your Room:

Floor area:

Required CADR:

Based on air changes per hour

Air Purifiers Meet Your Needs:

💡 Pro Tip: Products with published CADR ratings are shown first (most accurate). Others are matched by coverage area.

Did you know? Running a 45W purifier 24/7 costs ~$51/year, while an 8W purifier costs only ~$9/year at average US electricity rates!

Calculate Your Annual Electricity Cost

Purifier Specs

Power Consumption (Watts)

Check product specs or our data (150 products have this info)

💡 Typical Wattages:
• Small purifiers: 8-25W
• Medium purifiers: 25-60W
• Large purifiers: 60-150W
• Industrial: 150-300W

Usage Pattern

Hours per Day

Electricity Rate ($/kWh)

US average: $0.13/kWh. Check your electric bill.

Daily Energy Cost:

$/day

Using kWh per day

Monthly Energy Cost:

$/month

Annual Energy Cost:

$/year

Total: kWh per year

💡 Energy Efficiency Comparison

If you switched to a purifier using 50% less power:
You'd save: $/year
3-year savings: $

💡 Energy-efficient purifiers (≤30W) pay for themselves through lower electricity bills!

⚠️ The Truth: A $50 purifier with $80/year filters + $50/year energy = $530 over 3 years. A $200 purifier with $30/year filters + $20/year energy = $350 over 3 years. The "cheap" one costs more!

Calculate Total Cost Over 1, 3, and 5 Years

Initial Purchase

Purifier Price

Power Consumption (Watts)

Daily Usage (hours)

Ongoing Costs

Filter Cost (per replacement)

Filter Lifetime (months)

Electricity Rate ($/kWh)

Year 1 Total Cost:

• Purifier: $
• Energy: $
• Filters: $ ( replacements)

3-Year Total Cost:

• Purifier: $ (one-time)
• Energy: $ (3 years)
• Filters: $ ( replacements)

5-Year Total Cost:

• Purifier: $
• Energy: $
• Filters: $ ( replacements)

💡 Cost Breakdown Analysis

Biggest ongoing cost:

Average monthly cost (Year 3): $/month

💡 Look for purifiers with low energy consumption AND affordable filter replacements for best long-term value!

Ready to Shop?

Now that you know what you need, compare 610 air purifiers by price, CADR, and features.

Compare Air Purifiers by Price →