# Weather & Environment calculators

> Heat index, wind chill, dew point, relative humidity, air density, pressure altitude, boiling point at altitude, carbon footprint of driving and electricity.

9 calculators. HTML index: https://tttkmbb.com/weather · JSON: https://tttkmbb.com/api/v1/calculators?category=weather

- [Heat Index Calculator](https://tttkmbb.com/weather/heat-index.md): Computes the NWS heat index ('feels like' temperature in the shade) from air temperature and relative humidity with the Rothfusz regression, including the NWS low- and high-humidity adjustments, and classifies the NWS risk category. Tool: `calculate_heat_index`.
- [Wind Chill Calculator](https://tttkmbb.com/weather/wind-chill.md): Computes the wind chill temperature from air temperature and wind speed with the 2001 JAG/TI formula used by the US National Weather Service and Environment Canada, and reports the frostbite risk band for exposed skin. Tool: `calculate_wind_chill`.
- [Dew Point Calculator](https://tttkmbb.com/weather/dew-point.md): Computes the dew point temperature from air temperature and relative humidity with the Magnus formula (Alduchov & Eskridge coefficients a = 17.625, b = 243.04 °C), plus vapour pressures and a comfort classification. Tool: `calculate_dew_point`.
- [Relative Humidity Calculator](https://tttkmbb.com/weather/relative-humidity.md): Computes relative humidity from air temperature and dew point as the ratio of Magnus-formula vapour pressures, and the absolute humidity (grams of water vapour per cubic metre) from the ideal-gas law for water vapour. Tool: `calculate_relative_humidity`.
- [Air Density Calculator](https://tttkmbb.com/weather/air-density.md): Computes the density of humid air from temperature, station pressure and relative humidity as a mixture of ideal gases (dry air plus water vapour, vapour pressure from the Magnus formula), and the ISA density altitude. Tool: `calculate_air_density`.
- [Pressure Altitude Calculator](https://tttkmbb.com/weather/pressure-altitude.md): Converts between pressure and altitude in the ICAO International Standard Atmosphere: pressure altitude from station pressure (or from QNH/altimeter setting plus field elevation), and the ISA pressure and temperature at a given altitude. Tool: `convert_pressure_altitude`.
- [Boiling Point at Altitude Calculator](https://tttkmbb.com/weather/boiling-point-altitude.md): Computes the boiling point of water at a given altitude by taking the ISA pressure at that altitude (or a measured station pressure) and solving the Antoine equation for water, with a note on cooking at altitude. Tool: `calculate_boiling_point_at_altitude`.
- [Driving Carbon Footprint Calculator](https://tttkmbb.com/weather/carbon-footprint-driving.md): Estimates tailpipe CO₂ (and CO₂-equivalent including methane and nitrous oxide) for a car trip from distance and fuel economy or fuel used, using per-litre combustion factors for petrol, diesel and LPG, and scales to a yearly total. Tool: `estimate_driving_carbon_footprint`.
- [Electricity Carbon Footprint Calculator](https://tttkmbb.com/weather/carbon-footprint-electricity.md): Multiplies electricity consumption by a regional grid emission factor (world, US, Australia, EU, China, India or a custom value, kg CO₂ per kWh) to estimate monthly and yearly CO₂, and expresses the yearly total as mature-tree absorption years. Tool: `estimate_electricity_carbon_footprint`.