Weather and Climate

  • Rainfall Intensity Calculator
    Calculate rainfall intensity in mm/hr from rainfall depth and duration. Free, instant rain intensity calculator with category classification.
  • Heating & Cooling Degree Days Calculator
    Calculate heating (HDD) and cooling (CDD) degree days from daily high/low temperatures and a base temperature. Estimate energy demand over any period.
  • Final Temperature of Mixing Two Liquids Calculator
    Calculate the final equilibrium temperature when two liquids (such as water) of different masses, specific heats, and temperatures are mixed together.
  • Specific Heat Capacity Calculator
    Calculate specific heat capacity from heat energy, mass and temperature change using c = Q / (m·ΔT). Fast, accurate physics tool with worked example.
  • Heat Transfer Rate Calculator
    Calculate heat energy transferred (Q = mcΔT) from mass, specific heat, and temperature change. Free physics calculator with joules and kilojoules output.
  • Wind Chill Temperature Calculator
    Calculate wind chill ("feels like") temperature in °F from air temperature and wind speed using the official NWS 2001 wind chill formula.
  • Dew Point Calculator
    Calculate dew point from air temperature and relative humidity using the Magnus formula. Free, accurate dew point calculator in °C for any climate.
  • CO₂-Equivalent (GWP) Greenhouse Gas Calculator
    Convert methane, nitrous oxide, HFCs and CO₂ emissions into a single CO₂-equivalent (CO₂e) figure using 100-year Global Warming Potential factors.
  • Car Trip Carbon Footprint Calculator
    Calculate the CO₂ emissions of a car trip from distance, fuel economy and fuel type. Split the footprint per passenger and see grams of CO₂ per km.
  • PM2.5 to AQI Calculator (US EPA)
    Convert a PM2.5 concentration (µg/m³) into the US EPA Air Quality Index (AQI) using official piecewise linear interpolation and category breakpoints.
  • Relative Humidity from Wet & Dry Bulb Calculator
    Calculate relative humidity from dry-bulb and wet-bulb temperatures (psychrometer) using the psychrometric equation and Magnus saturation vapour pressure.
  • Rational Method Stormwater Runoff Calculator
    Calculate peak stormwater runoff with the Rational Method Q=CiA. Enter runoff coefficient, rainfall intensity and drainage area for US (cfs) or SI (m³/s).
  • Wind Power Density Calculator
    Calculate wind power density in W/m² from air density and wind speed using P/A = 0.5·ρ·v³. Free, fast wind energy resource tool.
  • Beaufort Wind Scale Calculator
    Convert wind speed (m/s, km/h, mph, knots) to the Beaufort force number 0-12 with description. Free Beaufort wind scale calculator.
  • Dew Point Calculator
    Calculate dew point from air temperature and relative humidity using the Magnus-Tetens formula. Instant results in °C with dew point spread.
  • Linear Thermal Expansion Calculator
    Calculate linear thermal expansion (ΔL = α·L₀·ΔT) from the expansion coefficient, original length, and temperature change. Free physics tool.
  • Average Temperature Calculator
    Calculate the daily mean (average) temperature from the day's high and low using T_avg = (T_max + T_min) / 2. Works in °C or °F.
  • Car CO₂ Emissions from Fuel Calculator
    Calculate the kilograms of CO₂ produced from burning petrol or diesel. Enter liters or US gallons of fuel to get your carbon emissions instantly.
  • Carbon Offset Trees Calculator
    Find how many trees you need to plant to offset your annual CO₂ emissions. Free carbon offset calculator using ~21 kg CO₂ absorbed per tree per year.
  • HVAC BTU Calculator — AC Size by Room
    Calculate the BTU cooling capacity you need by room size. Enter length, width, occupants and sun exposure to size your AC unit correctly.
  • Celsius to Fahrenheit Travel Converter
    Convert Celsius to Fahrenheit instantly for travel. Enter °C and get °F using F = C×9/5 + 32. Perfect for packing and weather planning abroad.
  • Snow Load on Roof Calculator
    Estimate roof snow load in psf from snow depth and density, or via the ASCE 7 flat-roof formula pf = 0.7·Ce·Ct·Is·pg.
  • Barometric Pressure Unit Converter
    Convert barometric pressure between hPa, inHg, mb, mmHg and psi instantly. Enter any value and unit to see all weather pressure equivalents.
  • Headwind & Crosswind Component Calculator
    Calculate headwind, tailwind and crosswind components from wind speed, wind direction and runway heading. Free aviation wind component calculator.

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