Weather and Climate

  • Lightning Distance Calculator
    Enter the seconds between a lightning flash and thunder to estimate how far away the strike is, calculated in kilometers using the 5-second rule.
  • Rainfall Calculator
    Enter rainfall amount (mm) and catchment area (m²) to calculate collected water volume (m³) for quick, simple water planning.
  • Beer Can vs. Beer Bottle CO2 Emissions Calculator
    Compare the life-cycle CO2 emissions of 500 ml aluminum beer cans versus glass beer bottles. Editable emission factors; defaults from a Japanese LCA study.
  • 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.
  • Earthquake Magnitude Difference & Energy Ratio Comparison Calculator
    Compare two earthquakes: get the magnitude difference and seismic energy ratio using the standard Gutenberg-Richter relation log10(J)=4.8+1.5M. Universal physics tool.
  • 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.
  • 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.
  • Apparent Temperature Calculator (Improved Missenard Formula)
    Compute the apparent (feels-like) temperature from air temperature, relative humidity and wind speed using the improved Missenard formula. Universal, in degC, %, m/s.
  • Sunrise, Sunset and Solar Transit Table Calculator
    Build a daily table of sunrise, solar noon (transit) and sunset times for any latitude/longitude and UTC offset over 1 week to 2 months, using the NOAA sunrise equation.
  • SMOG Air Quality Index (AQI) Calculator
    Convert PM2.5, PM10 or ozone concentration into the US EPA Air Quality Index (AQI) using the official piecewise linear breakpoint formula.
  • Annual Solar Elevation & Azimuth Calculator
    Compute the Sun's elevation (altitude) and azimuth at your location for each week of a year at a fixed local clock time. Works worldwide; default Tokyo/JST.
  • Windsock Wind Speed Calculator
    Estimate wind speed from a windsock's angle. Enter the angle from vertical (0–90°) and the full-extension speed to get knots, mph, and km/h.
  • Temperature Unit Converter (Kelvin, Celsius, Fahrenheit, Rankine)
    Convert any temperature between Kelvin, Celsius, Fahrenheit and Rankine at once. Enter one value, pick its unit, and get all four scales instantly.
  • Destination Temperature and Air Pressure Estimator (from elevation change)
    Estimate temperature and atmospheric pressure at a destination from your current temperature, pressure and altitude using the standard-atmosphere lapse-rate and barometric formula.
  • Sea-Level Pressure Correction Calculator
    Reduce a station barometric pressure to equivalent sea-level pressure using altitude and temperature with the standard barometric formula. Universal physics tool.
  • Discomfort Index (THI) Calculator
    Calculate the Discomfort Index (Temperature-Humidity Index) from air temperature and relative humidity, and see the comfort sensation category instantly.
  • Solar Elevation and Azimuth Daily Calculator
    Compute the Sun's elevation (altitude) and azimuth for every hour of a day at any latitude, longitude and date. Universal astronomy; defaults to Tokyo, UTC+9.
  • Sunlight Hours Affected by a South-Side Building
    Estimate how a building to the south blocks your home's direct sunlight. Compute residual sunlight hours, blocked window and critical roofline angle by latitude and date.
  • Hot Car Temperature Calculator
    Estimate how hot the inside of a parked car gets over time. Enter outside temperature and minutes to see the dangerous interior heat rise.
  • Altitude to Air Pressure Calculator
    Calculate local atmospheric pressure at any altitude from elevation, air temperature and sea-level pressure using the standard barometric formula.
  • Air Pressure at Altitude Calculator
    Calculate atmospheric pressure at any altitude using the barometric formula. Enter altitude and sea-level pressure to get hPa, kPa, and atm.
  • Air Density Calculator
    Calculate the density of dry air from pressure and temperature using the ideal gas law (ρ = P / (R·T), R = 287.058 J/kg·K).
  • Tree Benefits Calculator
    Estimate the annual CO₂ sequestered by your trees. Enter the number of trees and CO₂ absorbed per tree to see total carbon captured per year.
  • Earthquake Epicenter Distance Calculator (Omori's Formula)
    Estimate the distance to an earthquake's hypocenter from the P-wave to S-wave arrival gap using Omori's formula d = k x t. Universal seismology tool.

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