Terms

Effective 8 October 2026

The Page

Psychrometry is a free psychrometric chart published by PaintedApp, LLC. It computes the properties of moist air from two readings and an altitude, draws them on a chart, and works out the leaving air and the load of four air-conditioning processes. Using it needs no account and costs nothing. By using the page you accept these terms; if you do not accept them, please do not use it.

Readings, Not Engineering Sign-Off

The figures on the page are computed from the published equations it cites, under the assumptions it states: moist air as an ideal-gas mixture, the standard atmosphere for the altitude given, steady flow, and a coil described only by its apparatus dew point and bypass factor. They are a reading, not a design. Sizing equipment, specifying a building's ventilation or deciding whether a wall assembly will hold moisture is work for a qualified engineer, using the equipment maker's own data and the codes that apply where you build.

The comfort zones are a model of how most people in stated clothing and activity feel. They are not medical advice and say nothing about any one person's health.

Accuracy

Every figure is computed from cited sources, and the page lists those sources and the tests that check it against published values, with the largest disagreement printed. We work to keep it right, and the page is still provided as it is, without any warranty that it is free of error or fit for a particular purpose. To the extent the law allows, PaintedApp, LLC is not liable for a decision made on the page's figures.

Other People's Work

The equations are those of the ASHRAE Handbook—Fundamentals (2017), chapter 1, implemented and cited by number; none of the Handbook's tables or figures is reproduced, and the Handbook remains the copyright of ASHRAE. The test values and the method of solving them follow PsychroLib, by D. Meyer and D. Thevenard, under the MIT licence. The comfort validation points are from the validation-data-comfort-models project, under the MIT licence.

The page's own code is published under the MIT licence.

Fair Use of the Site

Please do not try to disrupt the site, overload it, or use it to harm anyone. Linking to any view of the page is welcome.

Changes and Contact

If these terms change, the new text will be published here with a new effective date. Questions go to support@painted.app.