Vapor Pressure Deficit (VPD) Calculator
Calculate vapor pressure deficit (VPD) from temperature and humidity — a key driver of transpiration and greenhouse climate.
VPD is the 'drying power' of the air — the gap between how much moisture the air holds and how much it could hold. It drives transpiration and is central to greenhouse climate control: 0.4–1.25 kPa is ideal; too low risks disease and weak transpiration, too high stresses plants and closes stomata.
Indicative planning figures based on published research averages. Local soil tests, varieties and weather change actual requirements — confirm with your agronomist or extension officer.
Orchardists and growers use the free Vapor Pressure Deficit (VPD) Calculator for an accurate answer in seconds — no formulas to remember, works offline in the orchard.
About Vapor Pressure Deficit (VPD) Calculator
Vapor pressure deficit (VPD) is increasingly used instead of plain humidity to manage protected cultivation, because it reflects the actual drying power the plant experiences and drives transpiration, nutrient uptake and disease pressure. This tool computes VPD from temperature and humidity and flags the zone: the 0.4–1.25 kPa band is generally ideal, below it invites fungal disease and weak transpiration, above it stresses plants and shuts stomata. Essential for greenhouse and polyhouse growers.
How to use Vapor Pressure Deficit (VPD) Calculator
- 1Enter your values into the inputs.
- 2Read the headline result and the supporting breakdown.
- 3Apply the guidance in the note to your orchard decisions.
Why use Vapor Pressure Deficit (VPD) Calculator?
- ✓Uses the standard, citable formula
- ✓Clear inputs with sensible defaults
- ✓Instant result with the working shown
- ✓Free, fully in-browser and private
Frequently asked questions
What is vapor pressure deficit (VPD)?+
It's the difference between the water vapour the air currently holds and the maximum it could hold at that temperature, in kPa. It measures the air's drying power and drives plant transpiration — a better climate guide than relative humidity alone.
What is a good VPD for plants?+
Roughly 0.4–1.25 kPa for most crops (lower for propagation/seedlings, higher for mature fruiting plants). Below ~0.4 kPa the air is too humid (disease, weak transpiration); above ~1.6 kPa plants stress and close stomata, slowing growth.
Is this tool free and private?+
Yes — free, no sign-up, and all calculation runs in your browser, so it works offline in the orchard and your data never leaves the device.
Related Agri tools
Tractor Fuel Consumption Calculator
Estimate your tractor's diesel consumption per hour from its horsepower, load and specific fuel consumption.
● LiveTractor Fuel Cost Per Acre Calculator
Convert your tractor's fuel use per hour into diesel litres and cost per acre for any field operation.
● LiveImplement Field Capacity Calculator
Calculate the effective field capacity (ha/h and acres/h) of any implement from width, speed and field efficiency.
● Live