Category
Earth & Weather
Great-circle navigation, sunrise and moon phase, wind chill, humidity, UV exposure, and atmospheric calculations.
Calculate great-circle distance, antipodes, wind chill, heat index, dew point, UV exposure, and growing degree days from inputs you control. Useful for navigation, gardening, outdoor safety, and weather literacy.
20 tools · Private · Browser-only
Featured calculators
Popular starting points for earth & weather homework and quick checks.
Wind Chill Calculator
Feels-like temperature with wind (US formula).
OpenHeat Index Calculator
Apparent temperature from heat and humidity.
OpenGreat Circle Distance Calculator
Shortest path distance over a sphere.
OpenDew Point Calculator
Dew point from temperature and humidity.
OpenUV Index Calculator
Estimated UV index from sun angle.
OpenSunrise Sunset Calculator
Approximate sun times for a location and day.
OpenRecently added & popular
Guides & comparisons
Wind Chill Explained: Feels-Like Temperature in Cold Weather
Wind strips the insulating layer of warm air from skin. At 0°F with 20 mph wind, exposed flesh can freeze in minutes even though the thermometer reads a static number.
Heat Index vs Air Temperature: Humidity and Feels-Like Heat
At 90°F and 70% humidity, your body struggles to cool by sweating — the heat index can exceed 105°F even though the thermometer reads lower.
How Rainfall Is Measured: Gauges, Radar, and Units
Rainfall is reported as vertical depth — 25 mm in a day means water would stand 25 mm deep on a flat surface if none ran off.
What Is Dew Point? Moisture, Fog, and Comfort
Dew point is the temperature air must cool to for saturation. A 70°F dew point feels steamy; below 55°F feels comfortable.
Earth
Antipode Calculator
Find the point on Earth directly opposite any location.
OpenLatitude Longitude Distance Calculator
Great-circle distance between two coordinate pairs.
OpenAzimuth Calculator
Initial bearing between two coordinates.
OpenGreat Circle Distance Calculator
Shortest path distance over a sphere.
OpenSunrise Sunset Calculator
Approximate sun times for a location and day.
OpenMoon Phase Calculator
Moon phase and illumination for a date.
OpenWeather
Wind Chill Calculator
Feels-like temperature with wind (US formula).
OpenHeat Index Calculator
Apparent temperature from heat and humidity.
OpenDew Point Calculator
Dew point from temperature and humidity.
OpenHumidity Calculator
Relative humidity from temp and dew point.
OpenRainfall Calculator
Rain volume from area and depth.
OpenRain to Snow Calculator
Convert liquid rain to snow depth.
OpenSnowfall Calculator
Snow depth from liquid equivalent.
OpenUV Index Calculator
Estimated UV index from sun angle.
OpenSunburn Time Calculator
Minutes to burn by skin type and UV.
OpenSun Exposure Calculator
UV dose from UV index and duration.
OpenClimate
Frequently asked questions
- Which distance formula is used?
- Great-circle and latitude-longitude tools use the haversine formula on a spherical Earth model — accurate for most navigation planning.
- Are weather indices official?
- Wind chill, heat index, and UV tools apply published approximation formulas. They are educational, not meteorological forecasts.
- Where should I start?
- Try wind chill or heat index for outdoor safety, great-circle distance for travel, or dew point for humidity understanding.