{"success":true,"version":"v1","request":{"tool":"list_calculators","category":"weather"},"result":{"entity_type":"calculator_list","status":"completed","count":9,"calculators":[{"calculator_id":"heat-index","entity_type":"calculator","name":"Heat Index Calculator","category":"weather","tool_name":"calculate_heat_index","description":"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.","use_when":"You need how hot humid weather feels, the NWS heat-index category (caution to extreme danger) or a heat-safety threshold for temperatures of 80 °F (27 °C) and above.","do_not_use_when":"Temperatures are below about 80 °F (27 °C), where the heat index is not meaningful (for cold weather use wind-chill), or you need the dew point itself (use dew-point).","required_inputs":["temperature","relative_humidity_percent"],"optional_inputs":["temperature_unit"],"urls":{"html":"https://tttkmbb.com/weather/heat-index","markdown":"https://tttkmbb.com/weather/heat-index.md","schema":"https://tttkmbb.com/api/v1/calculators/heat-index","api":"https://tttkmbb.com/api/v1/calculate/heat-index"}},{"calculator_id":"wind-chill","entity_type":"calculator","name":"Wind Chill Calculator","category":"weather","tool_name":"calculate_wind_chill","description":"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.","use_when":"You need the 'feels like' temperature in cold windy weather, or how quickly exposed skin can freeze, for temperatures at or below 10 °C (50 °F) and winds of at least 4.8 km/h (3 mph).","do_not_use_when":"The temperature is above 10 °C (50 °F) or the wind is below 4.8 km/h (the formula is undefined there); for hot humid weather use heat-index.","required_inputs":["temperature","wind_speed"],"optional_inputs":["temperature_unit","wind_speed_unit"],"urls":{"html":"https://tttkmbb.com/weather/wind-chill","markdown":"https://tttkmbb.com/weather/wind-chill.md","schema":"https://tttkmbb.com/api/v1/calculators/wind-chill","api":"https://tttkmbb.com/api/v1/calculate/wind-chill"}},{"calculator_id":"dew-point","entity_type":"calculator","name":"Dew Point Calculator","category":"weather","tool_name":"calculate_dew_point","description":"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.","use_when":"You know temperature and relative humidity and need the dew point, the humidity comfort level, or the temperature at which condensation forms on a surface.","do_not_use_when":"You know the dew point and need relative humidity or absolute humidity (use relative-humidity), or the temperature is below −40 °C or above 50 °C where the Magnus fit is not validated.","required_inputs":["temperature","relative_humidity_percent"],"optional_inputs":["temperature_unit"],"urls":{"html":"https://tttkmbb.com/weather/dew-point","markdown":"https://tttkmbb.com/weather/dew-point.md","schema":"https://tttkmbb.com/api/v1/calculators/dew-point","api":"https://tttkmbb.com/api/v1/calculate/dew-point"}},{"calculator_id":"relative-humidity","entity_type":"calculator","name":"Relative Humidity Calculator","category":"weather","tool_name":"calculate_relative_humidity","description":"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.","use_when":"A weather report gives temperature and dew point and you need the relative humidity, or you need the water-vapour content of air in g/m³ (e.g. for drying, greenhouses or HVAC).","do_not_use_when":"You have relative humidity and need the dew point (use dew-point), or you need humidity ratio in g/kg of dry air, which also requires the air pressure.","required_inputs":["temperature","dew_point"],"optional_inputs":["temperature_unit"],"urls":{"html":"https://tttkmbb.com/weather/relative-humidity","markdown":"https://tttkmbb.com/weather/relative-humidity.md","schema":"https://tttkmbb.com/api/v1/calculators/relative-humidity","api":"https://tttkmbb.com/api/v1/calculate/relative-humidity"}},{"calculator_id":"air-density","entity_type":"calculator","name":"Air Density Calculator","category":"weather","tool_name":"calculate_air_density","description":"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.","use_when":"You need air density for aerodynamics, engine or fan performance, ballistics or HVAC, or the density altitude for aircraft performance planning.","do_not_use_when":"You only have sea-level (QNH) pressure and no elevation (convert to station pressure with pressure-altitude first), or you need gas density for a gas other than air (use ideal-gas-law).","required_inputs":["temperature","pressure"],"optional_inputs":["temperature_unit","pressure_unit","relative_humidity_percent"],"urls":{"html":"https://tttkmbb.com/weather/air-density","markdown":"https://tttkmbb.com/weather/air-density.md","schema":"https://tttkmbb.com/api/v1/calculators/air-density","api":"https://tttkmbb.com/api/v1/calculate/air-density"}},{"calculator_id":"pressure-altitude","entity_type":"calculator","name":"Pressure Altitude Calculator","category":"weather","tool_name":"convert_pressure_altitude","description":"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.","use_when":"You need pressure altitude for aviation performance, the standard pressure or temperature at an altitude, or station pressure from a sea-level-reduced reading and elevation.","do_not_use_when":"You need true altitude on a non-standard day (that requires temperature correction), altitudes above 11 km (stratosphere), or the density altitude (use air-density).","required_inputs":[],"optional_inputs":["pressure","pressure_unit","elevation_m","altitude_m"],"urls":{"html":"https://tttkmbb.com/weather/pressure-altitude","markdown":"https://tttkmbb.com/weather/pressure-altitude.md","schema":"https://tttkmbb.com/api/v1/calculators/pressure-altitude","api":"https://tttkmbb.com/api/v1/calculate/pressure-altitude"}},{"calculator_id":"boiling-point-altitude","entity_type":"calculator","name":"Boiling Point at Altitude Calculator","category":"weather","tool_name":"calculate_boiling_point_at_altitude","description":"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.","use_when":"You need the boiling temperature of water at your elevation for cooking, canning, brewing, candy making or laboratory work, or the boiling point at a measured barometric pressure.","do_not_use_when":"You need the boiling point of a liquid other than water or of salt/sugar solutions (boiling-point elevation), or altitudes above 9000 m.","required_inputs":["altitude"],"optional_inputs":["altitude_unit","pressure_hpa"],"urls":{"html":"https://tttkmbb.com/weather/boiling-point-altitude","markdown":"https://tttkmbb.com/weather/boiling-point-altitude.md","schema":"https://tttkmbb.com/api/v1/calculators/boiling-point-altitude","api":"https://tttkmbb.com/api/v1/calculate/boiling-point-altitude"}},{"calculator_id":"carbon-footprint-driving","entity_type":"calculator","name":"Driving Carbon Footprint Calculator","category":"weather","tool_name":"estimate_driving_carbon_footprint","description":"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.","use_when":"You want the CO₂ emissions of a commute, road trip or annual mileage for a petrol, diesel or LPG vehicle, in kilograms and grams per kilometre.","do_not_use_when":"The vehicle is electric or plug-in hybrid (use carbon-footprint-electricity with the kWh consumed), you need lifecycle/well-to-wheel emissions, or you only need the fuel cost (use fuel-cost).","required_inputs":["distance"],"optional_inputs":["distance_unit","fuel_economy","fuel_economy_unit","fuel_used_liters","fuel_type","trips_per_year"],"urls":{"html":"https://tttkmbb.com/weather/carbon-footprint-driving","markdown":"https://tttkmbb.com/weather/carbon-footprint-driving.md","schema":"https://tttkmbb.com/api/v1/calculators/carbon-footprint-driving","api":"https://tttkmbb.com/api/v1/calculate/carbon-footprint-driving"}},{"calculator_id":"carbon-footprint-electricity","entity_type":"calculator","name":"Electricity Carbon Footprint Calculator","category":"weather","tool_name":"estimate_electricity_carbon_footprint","description":"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.","use_when":"You want the CO₂ emissions of a household or device's electricity use, an EV's charging, or to compare regions' grid intensities.","do_not_use_when":"You know your supplier's specific factor or use certified renewable energy (enter it as a custom factor), or you need the cost of the electricity (use electricity-cost).","required_inputs":["electricity_kwh"],"optional_inputs":["period","region","custom_factor_kg_per_kwh"],"urls":{"html":"https://tttkmbb.com/weather/carbon-footprint-electricity","markdown":"https://tttkmbb.com/weather/carbon-footprint-electricity.md","schema":"https://tttkmbb.com/api/v1/calculators/carbon-footprint-electricity","api":"https://tttkmbb.com/api/v1/calculate/carbon-footprint-electricity"}}]},"timestamp":"2026-09-24T01:53:37Z","next_actions":[],"links":{"docs":"https://tttkmbb.com/calculators.md"}}