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Calcimator

Visibility Calculator

Estimate atmospheric visibility from humidity, precipitation rate, and particulate concentration. Provides aviation flight category and driving safety guidance.

Inputs

%
mm/hr
μg/m³

Results

Visibility

11.95 km

≈ 36 Eiffel Towers

Aviation Category

VFR

Visibility7.43 miles
Visibility11,950 m
Driving SafetyNormal driving conditions
Primary Limiting FactorPrecipitation
How to Use This Calculator
  1. Enter relative humidity (%) — high humidity from fog and mist is the primary visibility reducer.
  2. Set precipitation rate (mm/hr) — heavier rain, snow, or freezing rain dramatically cuts visibility.
  3. Enter PM2.5 particulate concentration (µg/m³) for smoke, haze, or dust effects.
  4. Review Visibility (km), Visibility (miles), and Visibility (meters) for your conditions.
  5. Use Aviation Category (VFR/MVFR/IFR/LIFR) and Driving Safety rating for activity planning.

What each input means

Relative Humidity
Relative humidity as a percentage. Visibility drops sharply above 90% as fog and mist form.
Precipitation Rate
Rainfall intensity in millimeters per hour. Light rain is 0.5-2, moderate 2-7, heavy >7 mm/hr.
Particulate (PM2.5)
Fine particulate matter concentration. Good air: <12, moderate: 12-35, unhealthy: 35-150, hazardous: >250 μg/m³.

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    Relative Humidity = 85, Precipitation Rate = 2, Particulate (PM2.5) = 25 = 3 input(s) provided
  2. Calculate Visibility
    Visibility
    11.95 = 11.95
  3. Calculate Aviation Category
    Aviation Category
    VFR = VFR
  4. Calculate Visibility
    Visibility
    7.43 = 7.43
  5. Calculate Visibility
    Visibility
    11950 = 11950

Engine last updated . Checked against 1 independently-derived test — how we verify calculators.

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