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Whiz Tools

Air Changes Per Hour Calculator - Free ACH Tool

Calculate air changes per hour (ACH) instantly for any room. Get accurate ventilation rates, ASHRAE compliance, and air quality assessments for optimal indoor environments.

Hourly Air Exchange Calculator

Room Information

Room Dimensions

ft
ft
ft

Ventilation Information

CFM

Results

Room Volume

0.00 ft³

Air Changes per Hour (ACH)

0.00 ACH

Air Quality: Poor

Calculation Formula

ACH = (Ventilation Rate × 60) ÷ Room Volume
0.00 = (100 CFM × 60) ÷ 0.00 ft³

Recommendations

The air exchange rate is very low. Consider increasing ventilation to improve indoor air quality.

Room Air Exchange Visualization

The visualization shows air flow patterns based on the calculated air changes per hour (ACH).

About Air Changes per Hour (ACH)

Air Changes per Hour (ACH) measures how many times the air volume in a space is replaced with fresh air every hour. It's a key indicator of ventilation effectiveness and indoor air quality.

Recommended ACH Values by Space Type

  • Residential spaces: 0.35-1 ACH (minimum), 3-6 ACH (recommended)
  • Office buildings: 4-6 ACH
  • Hospitals and healthcare facilities: 6-12 ACH
  • Industrial spaces: 4-10 ACH (varies by activity)
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Documentation

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