From converting between temperature scales to understanding how conditions actually feel outdoors, these tools cover the full range of thermal and humidity measurements. Convert instantly with the Celsius to Fahrenheit Calculator or the multi-scale Temperature Unit Converter, and check real-feel conditions with the Heat Index Calculator, Wind Chill Calculator, or the Dew Point Calculator.
Browse the popularity-ranked list, or open the Trending tab to see what others are looking up right now. Every calculator is free, needs no sign-up, and works on any device.
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Feels-Like Temperature CalculatorCalculate the feels-like temperature in °F. Uses the NWS Heat Index when hot, Wind Chill when cold and windy, or the actual temperature otherwise.
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Relative Humidity from Dew Point CalculatorCalculate relative humidity (%) from air temperature and dew point using the Magnus formula. Fast, accurate, and free online RH calculator.
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Mixing Two Fluids Final Temperature CalculatorCalculate the final equilibrium temperature when two fluids are mixed, using mass, specific heat, and starting temperatures. Free physics tool.
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CADR & Room Size CalculatorFind the maximum room size an air purifier can handle from its CADR rating. Calculate floor area in sq ft for any target air changes per hour (ACH).
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Celsius to Fahrenheit Travel ConverterConvert Celsius to Fahrenheit instantly for travel. Enter °C and get °F using F = C×9/5 + 32. Perfect for packing and weather planning abroad.
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HVAC BTU Calculator — AC Size by RoomCalculate the BTU cooling capacity you need by room size. Enter length, width, occupants and sun exposure to size your AC unit correctly.
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Dew Point CalculatorCalculate dew point from air temperature and relative humidity using the Magnus-Tetens formula. Instant results in °C with dew point spread.
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Linear Thermal Expansion CalculatorCalculate linear thermal expansion (ΔL = α·L₀·ΔT) from the expansion coefficient, original length, and temperature change. Free physics tool.
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Dew Point CalculatorCalculate dew point from air temperature and relative humidity using the Magnus formula. Free, accurate dew point calculator in °C for any climate.
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Heating & Cooling Degree Days CalculatorCalculate heating (HDD) and cooling (CDD) degree days from daily high/low temperatures and a base temperature. Estimate energy demand over any period.
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Specific Heat Capacity CalculatorCalculate specific heat capacity from heat energy, mass and temperature change using c = Q / (m·ΔT). Fast, accurate physics tool with worked example.
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Final Temperature of Mixing Two Liquids CalculatorCalculate the final equilibrium temperature when two liquids (such as water) of different masses, specific heats, and temperatures are mixed together.
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Heat Transfer Rate CalculatorCalculate heat energy transferred (Q = mcΔT) from mass, specific heat, and temperature change. Free physics calculator with joules and kilojoules output.
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Newton's Law of Cooling CalculatorCalculate the temperature of a cooling (or warming) object over time with Newton's Law of Cooling and find the thermal time constant τ = 1/k.
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Clausius–Clapeyron Vapor Pressure CalculatorEstimate vapor pressure at a new temperature with the Clausius–Clapeyron equation. Enter P1, T1, T2 and ΔHvap to find P2 instantly.
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Celsius to Fahrenheit Thermostat CalculatorConvert Celsius to Fahrenheit (and back) instantly. Perfect for setting your thermostat, cooking, and weather. Uses F = C × 9/5 + 32.
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Fahrenheit to Celsius Travel ConverterConvert Fahrenheit to Celsius instantly for travel. Enter any °F temperature and get the exact °C value using C = (F − 32) × 5/9.
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Fahrenheit to Celsius Fever CalculatorConvert body temperature between Fahrenheit and Celsius and instantly see whether the reading reaches the 38 °C / 100.4 °F fever threshold.
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Oven Temperature Conversion CalculatorConvert oven temperatures between Fahrenheit, Celsius and UK Gas Mark instantly. Enter any value and get all three equivalents for perfect baking.
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Ideal Gas Law Temperature CalculatorSolve for temperature using the ideal gas law T = PV/(nR). Enter pressure, volume, and moles to get the gas temperature in K, °C, and °F.
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Specific Gas Constant Air Density CalculatorCalculate humid air density from temperature, pressure and relative humidity using the specific gas constants for dry air and water vapor.
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R-Value & U-Value Insulation CalculatorCalculate the R-value (thermal resistance) and U-value of insulation from material thickness and thermal conductivity. Add extra layers for total R.
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Thermal Conduction Heat Flow CalculatorCalculate conductive heat flow rate and heat flux through a material using Fourier's Law: Q/t = k·A·ΔT/d. Enter conductivity, area, thickness and temperatures.
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Saturation Vapor Pressure CalculatorCalculate saturation vapor pressure from air temperature using the Tetens equation. Get results in kPa, hPa (mbar), and Pa instantly.
Frequently asked questions
What temperature and humidity calculations are available?
You can convert temperatures across Celsius, Fahrenheit, Kelvin, and Rankine; calculate the heat index and apparent temperature for hot, humid conditions; find the wind chill factor in cold weather; determine dew point from air temperature and relative humidity; and assess outdoor comfort with the Discomfort Index (THI).
How accurate are the results?
These calculators use widely accepted meteorological formulas — including the NWS heat index equation, the Steadman apparent-temperature model, and the Magnus-formula dew point approximation. Results are reliable estimates for typical atmospheric conditions. For engineering design, occupational health limits, or agricultural planning, double-check against authoritative meteorological standards or reference publications.
Are they free to use?
Yes, entirely free. No account or sign-up is required. Open any tool, enter your temperature or humidity values, and get an instant conversion or comfort index result on any device.
Do you store the temperature or humidity values I enter?
No. Every calculation runs entirely inside your browser. None of the temperature readings, humidity percentages, or location details you enter are transmitted to or stored on our servers — your inputs stay on your device.
Which tools are the most popular in this category?
The list is ranked by real visitor usage, so the top entries are the tools people reach for most. Open the Trending tab to see what's gaining traction lately, or check Recently Added to find the newest calculators in this category.
