VPD Calculator — Vapour Pressure Deficit From Your Own Data
Most VPD calculators take one temperature and one humidity and give you one number. Drop a logger export in here instead and get the deficit as a series over the whole record — air VPD, and leaf VPD at whatever leaf-temperature offset you are prepared to assert — computed from FAO-56 Equation 11, with the equation printed on the figure so the arithmetic can be checked against the paper it came from.
Your data
Drop a logger CSV here
HOBOware and Postlad exports are recognised automatically. It is read on this machine — nothing is uploaded.
Synthetic three-day propagation-house record at fifteen-minute intervals, in the Postlad stream-export layout and declaring UTC. Nights are near-saturated and afternoons are warm and dry, so both the air and leaf deficits swing across the range a grower cares about. Not measured data.
SVG is vector — scale it to any size in Illustrator, Inkscape or LaTeX without losing quality, and edit the type. Use it unless a journal insists on raster.
Options
Series
In °C. This tool never converts units.
In percent, 0–100.
Leaf
An assumption, not a measurement. A transpiring leaf runs cooler than the air; a sunlit one under still air can run warmer.
Figure
All of that was worked out in this browser tab. Your file was not uploaded, and no request goes out while you work — open the network panel and watch, if you like.