Free climate tool

Cannabis VPD Calculator

VPD shows how strongly the air pulls water from your plants. It combines temperature and relative humidity (RH) into one value.

Your VPD

Your leaf VPD is within the target range for Vegetative growth.

0.91 kPa

On target

Target range: 0.8–1.2 kPa leaf VPD

Details

Air VPD1.27 kPa

Dew point16.7 °C

Next step

No change needed.

Guide ranges by growth phase

The target ranges are guide values based on manufacturer data, not a diagnosis. Every strain and grow tent is different, so watch your plants.

Growth phase	Leaf VPD target range
Clone/seedling	0.4–0.8 kPa
Vegetative growth	0.8–1.2 kPa
Early flowering	1.0–1.3 kPa
Late flowering	1.2–1.5 kPa

VPD chart by temperature and relative humidity

The chart shows leaf VPD with a leaf-temperature offset of −2 °C. Green cells are within the target range for the selected phase.

Scroll sideways to see all values.

Clone/seedling: 0.4–0.8 kPa

Temperature	0%	10%	20%	30%	40%	50%	60%	70%	80%	90%	100%
10 °C	1.07	0.95	0.83	0.70	0.58	0.46	0.34	0.21	0.09	−0.03	−0.16
15 °C	1.50	1.33	1.16	0.99	0.82	0.65	0.47	0.30	0.13	−0.04	−0.21
20 °C	2.06	1.83	1.60	1.36	1.13	0.89	0.66	0.43	0.19	−0.04	−0.27
25 °C	2.81	2.49	2.18	1.86	1.54	1.23	0.91	0.59	0.28	−0.04	−0.36
30 °C	3.78	3.36	2.93	2.51	2.08	1.66	1.23	0.81	0.39	−0.04	−0.46
35 °C	5.03	4.47	3.91	3.34	2.78	2.22	1.66	1.09	0.53	−0.03	−0.59
40 °C	6.62	5.89	5.15	4.41	3.67	2.94	2.20	1.46	0.72	−0.01	−0.75

Vegetative growth: 0.8–1.2 kPa

Temperature	0%	10%	20%	30%	40%	50%	60%	70%	80%	90%	100%
10 °C	1.07	0.95	0.83	0.70	0.58	0.46	0.34	0.21	0.09	−0.03	−0.16
15 °C	1.50	1.33	1.16	0.99	0.82	0.65	0.47	0.30	0.13	−0.04	−0.21
20 °C	2.06	1.83	1.60	1.36	1.13	0.89	0.66	0.43	0.19	−0.04	−0.27
25 °C	2.81	2.49	2.18	1.86	1.54	1.23	0.91	0.59	0.28	−0.04	−0.36
30 °C	3.78	3.36	2.93	2.51	2.08	1.66	1.23	0.81	0.39	−0.04	−0.46
35 °C	5.03	4.47	3.91	3.34	2.78	2.22	1.66	1.09	0.53	−0.03	−0.59
40 °C	6.62	5.89	5.15	4.41	3.67	2.94	2.20	1.46	0.72	−0.01	−0.75

Early flowering: 1.0–1.3 kPa

Temperature	0%	10%	20%	30%	40%	50%	60%	70%	80%	90%	100%
10 °C	1.07	0.95	0.83	0.70	0.58	0.46	0.34	0.21	0.09	−0.03	−0.16
15 °C	1.50	1.33	1.16	0.99	0.82	0.65	0.47	0.30	0.13	−0.04	−0.21
20 °C	2.06	1.83	1.60	1.36	1.13	0.89	0.66	0.43	0.19	−0.04	−0.27
25 °C	2.81	2.49	2.18	1.86	1.54	1.23	0.91	0.59	0.28	−0.04	−0.36
30 °C	3.78	3.36	2.93	2.51	2.08	1.66	1.23	0.81	0.39	−0.04	−0.46
35 °C	5.03	4.47	3.91	3.34	2.78	2.22	1.66	1.09	0.53	−0.03	−0.59
40 °C	6.62	5.89	5.15	4.41	3.67	2.94	2.20	1.46	0.72	−0.01	−0.75

Late flowering: 1.2–1.5 kPa

Temperature	0%	10%	20%	30%	40%	50%	60%	70%	80%	90%	100%
10 °C	1.07	0.95	0.83	0.70	0.58	0.46	0.34	0.21	0.09	−0.03	−0.16
15 °C	1.50	1.33	1.16	0.99	0.82	0.65	0.47	0.30	0.13	−0.04	−0.21
20 °C	2.06	1.83	1.60	1.36	1.13	0.89	0.66	0.43	0.19	−0.04	−0.27
25 °C	2.81	2.49	2.18	1.86	1.54	1.23	0.91	0.59	0.28	−0.04	−0.36
30 °C	3.78	3.36	2.93	2.51	2.08	1.66	1.23	0.81	0.39	−0.04	−0.46
35 °C	5.03	4.47	3.91	3.34	2.78	2.22	1.66	1.09	0.53	−0.03	−0.59
40 °C	6.62	5.89	5.15	4.41	3.67	2.94	2.20	1.46	0.72	−0.01	−0.75

Drying and curing

Different climate guide ranges apply during drying than during the growth phases.

Guide ranges for drying and curing

VPD frequently asked questions

What does VPD mean?

VPD means vapor pressure deficit. It combines temperature and relative humidity to describe how strongly the air can draw water from leaves.

Why does the calculator show leaf and air VPD?

Air VPD uses the air temperature. Leaf VPD also accounts for leaves often being cooler than the air. The target ranges use leaf VPD.

Which leaf-temperature offset should I use?

If you do not measure leaf temperature directly, −2 °C is a common guide value. An infrared thermometer gives you a more precise reading.

Which values apply to each phase?

The table lists guide ranges for clone/seedling, vegetative growth, early flowering and late flowering. They are not fixed rules or a diagnosis.

Do these values also apply to drying?

No. Different climate guide ranges apply to drying and curing.