# HumidCalc — Precision Moist Air Calculator > Precision calculator for humidity, air properties, and heat stress indices using weather data. (iPhone/iPad app by yoshihito sakagami.) - Source: https://appshunter.io/ios/app/humidcalc/id1135328698 (this page in markdown: same URL + `.md`) - Developer: [yoshihito sakagami](https://appshunter.io/developer/1112518506) - Category: Weather, Utilities - Price: Free - Rating: 5.00/5 from 1 App Store ratings · 2 written reviews indexed - Age rating: 4+ - Requires: iOS 15.6 · 11 MB - Languages: American English, Japanese, Chinese (Traditional, Taiwan) - Released: 2016-07-19 - Data updated: 2026-09-02 - Monetization: ad-supported - User reviews in markdown: https://appshunter.io/ios/app/humidcalc/id1135328698/reviews.md ## What is HumidCalc? ＊Weather data supported＊ A versatile humidity calculation app for everyone from general users to engineers — also suitable for agricultural applications. This app allows you to easily calculate indicators such as the Discomfort Index, WBGT (estimated heat stress index), Volumetric Absolute Humidity (an important indicator for influenza prevention), and Humidity Deficit (HD) used in agriculture, using weather data. You can also calculate a wide range of air properties from dry-bulb temperature (normal air temperature) and wet-bulb temperature obtained from ventilated psychrometers such as the Assmann psychrometer.
Atmospheric pressure can be entered manually. The app supports 12 indicators across 16 calculation items, and unit conversion between Celsius/Fahrenheit and SI/Imperial units can be performed instantly by switching the temperature unit setting. ■ High-Precision Calculation Engine This app uses the Wexler–Hyland equations combined with numerical analysis, enabling highly accurate and stable calculations across a wide range of environmental conditions. ■ Calculable Indicators * Wet Bulb Temperature * Dew Point Temperature * Frost point temperature * Relative Humidity * Humidity Ratio(Absolute Humidity) * Mass-based absolute humidity * High-resolution mass-based absolute humidity * Volumetric absolute humidity * Humidity Deficit (HD) * Vapor Pressure Deficit (VPD) * Enthalpy * Specific Volume * Saturation Vapor Pressure * Water Vapor Partial Pressure * Boiling Point of Water * WBGT (Estimated value) * Discomfort Index (DI) Supplementary Notes on WBGT & Discomfort Index Outdoor WBGT is defined as: WBGT = 0.7 Tnw + 0.1 Td + 0.2 Tg (°F) Since globe temperature (Tg) is not an input parameter, it is estimated from dry-bulb temperature (Td) using: Tg = 1.45 Td − 27.162 (°F) Td and Tg show a strong correlation (n = 17,376, R² = 0.919). Natural wet-bulb temperature (Tnw) is obtained by converting the measured wet-bulb temperature from an Assmann psychrometer to natural conditions, assuming a wind speed of 98.4 fpm (0.5 m/s) or less. Details of this conversion algorithm are omitted. The Discomfort Index (DI) is calculated as: DI = 0.4 × (Td + Tw) + 15 (°F). ■ Weather Data & Sensors By tapping the Weather Data button, you can obtain current atmospheric pressure, dry-bulb temperature, and wet-bulb temperature. On devices equipped with a barometric pressure sensor, pressing the MEAS button allows direct pressure measurement. Wet-bulb conditions can be set to Normal or Frozen (effective below freezing). Corrected values can also be displayed for non-ventilated psychrometers such as the August psychrometer (ventilated types recommended for accuracy). ■App Ecosystem Integration You can directly receive calculated dry-bulb and wet-bulb temperatures from the companion app “Calculator of Air”. (Please note that calculations must be performed in Calculator of Air before data can be transferred.) By combining HumidCalc with Calculator of Air, you can, for example, derive multiple air properties from known Enthalpy and Humidity Ratio values. ■Input Ranges * Dry-Bulb & Wet-Bulb Temperature: −22°F to 122°F (−30°C to 50°C) * Atmospheric Pressure: 17.72 inHg to 73.09 inHg (600 hPa to 2475 hPa) * Dew Point: −58°F to 122°F (−50°C to 50°C) * Relative Humidity: 0% to 100% (1% steps) ■Notes When using an August psychrometer, calculations assume an air velocity at the sensing element of 98.4 fpm (0.5 m/s) or less. As a result, calculated values may differ from those listed in humidity tables included with commercial August psychrometers. ■Disclaimer 1. Please use values within reasonable temperature ranges (approximately 32°F to 104°F / 0°C to 40°C). Extremely unusual inputs may produce inaccurate results. 2. While every effort has been made to ensure high precision, minor errors may occur due to floating-point limitations. 3. The developer assumes no responsibility for any damages resulting from the use of this app. ## Key features - Humidity and air property calculations - Discomfort Index and WBGT calculation - Volumetric Absolute Humidity for influenza prevention - Humidity Deficit (HD) for agriculture - Supports 11 indicators across 15 calculation items - Unit conversion (Celsius/Fahrenheit, SI/Imperial) - High-precision calculation engine ## Recent user reviews (2 of 2) All indexed reviews: https://appshunter.io/ios/app/humidcalc/id1135328698/reviews.md ### 5/5 — Good features, needs more info *2017-04-15* First I wish there was a paid option to not have ads. More importantly, I like the specific features but need more background on how some things are calculated. WBGT is 'estimated' but how? That is far from easy to do right. And what is the discomfort index reported? And there is no way to ask . Developer, please consider an update with info, And perhaps an ad free upgrade, and a way to ask such questions. Update (4/5/17): developer responded via App Store, thanks! But still have questions: how is WBGT estimated, and what discomfort index is used? Thank you. Update: 4/15/17. Thank you to the developer for the details on the wbgt estimation. The globe temperature is the hardest to accurately estimate, but thank you for listing your equation. Also thanks for listing the discomfort index equation in your app. I appreciate your support and use your app. Excellent post script- I give 5 stars now. **Developer response:** (4/11/17) Dear Tx9753. Thank you for your new question. I am sorry for the copy and paste from Description of the AppStore, this is the answer to your question. That’s because of my Japanese people,my not good at English. There may have been a strange part in sentence expression, apologize about this matter. At the risk of repetition, thank you for your comment. From the developers of this app. ★★ Supplementary explanation about the WBGT(Estimated value) and the Discomfort index. ★★ The calculation formula of the outdoor WBGT is "WBGT = 0.7 Tnw + 0.1 Td + 0.2 Tg", but since there is no entry item Globe thermometer temperature (Tg) in this application, estimation the Globe thermometer temperature(Tg) by Dry-bulb temperature (Td). - Calculation formula: "Tg = 1.45 Td - 27.162 [Temperature unit: ℉]” There is a very strong correlation between Globe thermometer temperature (Tg) and Dry-bulb temperature (Td). [Statistical information on this correlation : The number of samples is 17376 and the coefficient of determination(R^2) when statistics are taken is 0.919] For Natural wet-bulb temperature (Tnw), Convert the Wet-bulb temperature(Tw) obtained by measurement by Assmann psychrometer to the Wet-bulb temperature(Tw) measured in natural state, a use it as Natural wet-bulb temperature (Tnw). The natural state here means that the wind speed at the time of measurement is 5 meters per second(16.4 feet per second) or less. The algorithm of this conversion is very special, so we omit the explanation. "Discomfort Index" is "Temperature-humidity index". The calculation formula is "Discomfort Index[DI] = 0.4 × (Td + Tw) +15 [Temperature unit: ℉]". (4/5/17) Dear Tx9753. Thank you for your comment. You about the matter pointed out is wrote the answer on the Description section in the AppStore.Could you please view it if you don’t mind? I am sorry to you, but there is no plan for will change to paid application. Because of my Japanese people,my not good at English. There may have been a strange part in sentence expression, apologize about this matter. At the risk of repetition, thank you for your comment. From the developers of this app. ### 5/5 — 찾았다!!!! *2016-10-31* 찾았다. ㅜㅜ ## Frequently asked questions about HumidCalc ### What is HumidCalc used for? HumidCalc is a versatile humidity calculation app that helps users determine indicators like the Discomfort Index, WBGT, Volumetric Absolute Humidity, and Humidity Deficit. It's designed for general users, engineers, and agricultural applications. ### Does HumidCalc use weather data? Yes, HumidCalc supports weather data and can obtain current atmospheric pressure, dry-bulb temperature, and wet-bulb temperature. On devices with a barometric pressure sensor, it can also perform direct pressure measurements. ### What types of calculations does HumidCalc offer? HumidCalc supports 11 indicators across 15 calculation items, including Dew Point Temperature, Relative Humidity, Humidity Ratio, Humidity Deficit, Enthalpy, Specific Volume, WBGT, and Discomfort Index. ### Can HumidCalc convert units? Yes, HumidCalc allows for instant unit conversion between Celsius and Fahrenheit, and between SI and Imperial units by simply switching the temperature unit setting. ### How accurate are HumidCalc's calculations? HumidCalc utilizes a high-precision calculation engine based on the Wexler–Hyland equations combined with numerical analysis, ensuring highly accurate and stable calculations across a wide range of environmental conditions. ### Does HumidCalc have ads? Yes, HumidCalc contains advertisements. It is available for free and supported by ads. ### What devices is HumidCalc available on? HumidCalc is available on iPhone and iPod. It is designed for iOS devices. ### How often is HumidCalc updated? The latest version of HumidCalc is 1.2.7, which was last updated on April 19, 2026. This indicates a history of updates, though the exact frequency is not specified. ## Version history (last 5 releases) ### 1.2.8 — 2026-08-13 - Added "Auxiliary Input Mode," allowing numeric input for Dew Point Temperature and Relative Humidity. In addition to the standard input ("Atmospheric Pressure × Dry-Bulb Temperature × Wet-Bulb Temperature"), you can now enter values using two distinct modes: • Atmospheric Pressure × Dry-Bulb Temperature × Dew Point Temperature • Atmospheric Pressure × Dry-Bulb Temperature × Relative Humidity - Added Pictogram Indicators next to the WBGT (Estimated Value) and Discomfort Index numbers to help you visually check heatstroke risk and mugginess. (For pictogram types and threshold values, please check the 9th and 10th screenshots.) - Updated the ad format from standard Adaptive Banners to Collapsible Banners. [Important: How to use the new "Auxiliary Input Mode" & Tip] While this update adds support for Relative Humidity and Dew Point inputs, this app is designed to prioritize calculation based on the "Dry-Bulb Temperature × Wet-Bulb Temperature" combination. Therefore, changes in the Dry-Bulb or Wet-Bulb temperatures will automatically update and recalculate the Dew Point and Relative Humidity values accordingly. ● Tip for accurate input: Always enter and set the Dry-Bulb Temperature first. If you change the Dry-Bulb Temperature later, any previously entered Relative Humidity or Dew Point values will be automatically recalculated to match the new temperature. For a smooth experience, we recommend entering values from top to bottom, starting with Atmospheric Pressure! ### 1.2.7 — 2026-04-19 - Changed the ad banner from a Smart Banner to an Adaptive Banner. - Fixed a layout issue that occurred on some devices. - Updated to comply with the privacy requirements introduced in iOS 14 (IDFA and App Tracking Transparency). - Optimized the UI for 6.5-inch displays on iPhone X and later models. - Updated the AdMob advertising SDK. - Added calculation and display support for frost point temperature. - VPD (Vapor Pressure Deficit) is now displayed alongside humidity deficit values. - Improved the numerical analysis algorithms, resulting in faster calculations and accurate computation of relative humidity and dew point even at extremely low temperatures (below -238°F / −150 °C). (For temperature inputs below −22°F(−30 °C), please use the companion app “Calculator of Air”.) Please note: This version is not compatible with older versions of the companion app “Calculator of Air” (version 1.1.4 or earlier). Users who rely on app integration are kindly requested to update “Calculator of Air” to version 1.1.5 or later. ### 1.2.6 — 2026-03-03 - Fixed a layout issue that occurred on some devices. - Updated to comply with the privacy requirements introduced in iOS 14 (IDFA and App Tracking Transparency). - Optimized the UI for 6.5-inch displays on iPhone X and later models. - Updated the AdMob advertising SDK. - Added calculation and display support for frost point temperature. - VPD (Vapor Pressure Deficit) is now displayed alongside humidity deficit values. - Improved the numerical analysis algorithms, resulting in faster calculations and accurate computation of relative humidity and dew point even at extremely low temperatures (below -238°F / −150 °C). (For temperature inputs below −22°F(−30 °C), please use the companion app “Calculator of Air”.) Please note: This version is not compatible with older versions of the companion app “Calculator of Air” (version 1.1.4 or earlier). Users who rely on app integration are kindly requested to update “Calculator of Air” to version 1.1.5 or later. ### 1.2.5 — 2026-03-01 - Fixed a layout issue that occurred on some devices. - Updated to comply with the privacy requirements introduced in iOS 14 (IDFA and App Tracking Transparency). - Optimized the UI for 6.5-inch displays on iPhone X and later models. - Updated the AdMob advertising SDK. - Added calculation and display support for frost point temperature. - VPD (Vapor Pressure Deficit) is now displayed alongside humidity deficit values. - Improved the numerical analysis algorithms, resulting in faster calculations and accurate computation of relative humidity and dew point even at extremely low temperatures (below -238°F / −150 °C). (For temperature inputs below −22°F(−30 °C), please use the companion app “Calculator of Air”.) Please note: This version is not compatible with older versions of the companion app “Calculator of Air” (version 1.1.4 or earlier). Users who rely on app integration are kindly requested to update “Calculator of Air” to version 1.1.5 or later. ### 1.2.4 — 2026-02-22 - Fixed a layout issue that occurred on some devices. - Updated to comply with the privacy requirements introduced in iOS 14 (IDFA and App Tracking Transparency). - Optimized the UI for 6.5-inch displays on iPhone X and later models. - Updated the AdMob advertising SDK. - Added calculation and display support for frost point temperature. - VPD (Vapor Pressure Deficit) is now displayed alongside humidity deficit values. - Improved the numerical analysis algorithms, resulting in faster calculations and accurate computation of relative humidity and dew point even at extremely low temperatures (below -238°F / −150 °C). (For temperature inputs below −22°F(−30 °C), please use the companion app “Calculator of Air”.) Please note: This version is not compatible with older versions of the companion app “Calculator of Air” (version 1.1.4 or earlier). 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User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-09-02.*