# VPD Tool — Vapor Pressure Deficit Heatmap

> Calculate and visualize plant Vapor Pressure Deficit (VPD) with environmental data. (iPhone/iPad app by Nicholas Hwang.)

- Source: https://appshunter.io/ios/app/vpd-tool/id6751213834 (this page in markdown: same URL + `.md`)
- Developer: [Nicholas Hwang](https://appshunter.io/developer/1802240669)
- Category: Utilities, Weather
- Price: $0.49
- Rating: 5.00/5 from 1 App Store ratings · 1 written reviews indexed
- Age rating: 4+
- Requires: iOS 18.5 · 2 MB
- Languages: American English, French (France), Japanese, European Portuguese, European Spanish, Chinese (Traditional, Hong Kong SAR China)
- Released: 2025-08-19
- Data updated: 2026-09-01
- Monetization: paid
- User reviews in markdown: https://appshunter.io/ios/app/vpd-tool/id6751213834/reviews.md

## What is VPD Tool?

Know your VPD in seconds.
Enter temperature & humidity (or tap the interactive heatmap) to see Leaf VPD and Air VPD with scientifically labeled isolines. Choose Seedling / Veg / Flower / Late Flowering to see target VPD ranges and how best to nudge your environment to “ideal.”

Why growers love it
• Interactive heatmap: drag to explore temperature–humidity combos
• Stage presets: recommended VPD bands by plant development stage
• Leaf vs Air: leaf–air offset, dew point, absolute humidity
• Beautiful widgets: small/medium/large Home & Lock Screen widgets
• Private by design: on-device calculations, no account required

Details
• VPD = es(T) × (1 − RH/100); leaf VPD uses leaf temperature (air + ΔT)
• Absolute humidity via water vapor partial pressure (ideal gas law)
• Full support for °C/°F, metric/imperial
• Export logs to CSV


Support
Questions or feedback: support@nicksberryfarm.com

## Key features

- Interactive VPD heatmap
- Stage-specific VPD ranges
- Leaf and Air VPD calculation
- Home and Lock Screen widgets
- On-device calculations
- CSV log export

## Recent user reviews (1 of 1)

All indexed reviews: https://appshunter.io/ios/app/vpd-tool/id6751213834/reviews.md

### 5/5 — Sleek and  v useful

*2025-08-20*

Perfect widget and app for quick VPD check multiple times a day. 

Been looking for years for a VPD chart that looks and feels like this

## Frequently asked questions about VPD Tool

### What is VPD Tool used for?

VPD Tool helps growers understand and manage Vapor Pressure Deficit (VPD) for optimal plant growth. It provides real-time VPD calculations and recommendations based on temperature and humidity.

### How does VPD Tool calculate VPD?

VPD Tool uses the formula VPD = es(T) × (1 − RH/100), considering leaf temperature for leaf VPD and air temperature for air VPD. It also calculates absolute humidity via water vapor partial pressure.

### Does VPD Tool require an account?

No, VPD Tool is private by design and performs all calculations on-device. No account or internet connection is required to use its core features.

### What devices does VPD Tool support?

VPD Tool is available for iPhone and iPad devices, offering a convenient way to monitor plant environments on the go.

### How much does VPD Tool cost?

VPD Tool is a paid application, available for a one-time purchase of $0.49. This provides full access to all its features without ongoing costs.

### Can I export my VPD data from VPD Tool?

Yes, VPD Tool allows you to export your logged data to a CSV file. This enables further analysis and record-keeping of your environmental conditions.

### How often is VPD Tool updated?

The latest version of VPD Tool is 1.0.5, last updated on May 10, 2026. Updates typically focus on improving features and ensuring compatibility.

### What is the age rating for VPD Tool?

VPD Tool has an age rating of 4+, making it suitable for a wide range of users interested in plant care and environmental monitoring.

## Version history (last 5 releases)

### 1.0.5 — 2026-05-10

Heatmap improvements
- Enlarged on select widget sizes
- Improved tap accuracy

Performance and stability improvements.

### 1.0.3 — 2025-12-17

General Improvements
	•	Chart text color now matches the user defined cursor color.
	•	The charting pipeline now utilizes Leaf-Referenced VPD. By accounting for leaf temperature offsets, this metric better reflects the true vapor pressure gradient driving transpiration.

### 1.0.2 — 2025-12-12

VPD range updates (kPa)
	•	Refined Flower stage from [1.2–1.6] -> [1.2–1.5]
	•	Refined Late Flower stage from [1.4–1.8] -> [1.2–1.6]

UI & usability improvements
	•	Added tick marks to sliders so it’s easier to land on exact values.
	•	Moved Altitude into Settings. VPD values are calculated independently of altitude (pressure-independent).

### 1.0.1 — 2025-08-25

This release standardizes unit handling and expands modeling flexibility.
	•	Consistent Imperial-unit presentation across views and widgets
	•	Widget configuration now includes unit selection
	•	Leaf–air temperature differential (ΔT) supports negative values to represent cooler-leaf conditions

### 1.0 — 2025-08-19

No release notes.

## Apps similar to VPD Tool

| App | Rating | Price | Category |
| --- | --- | --- | --- |
| [Unplug Alarm Client](https://appshunter.io/ios/app/unplug-alarm-client/id1489026641) | 3.0 (1) | Free | Utilities |
| [VPD Chart](https://appshunter.io/ios/app/vpd-chart/id6470015847) | 4.5 (29) | Free | Utilities |
| [Simplify Fractions](https://appshunter.io/ios/app/simplify-fractions/id1569741008) | 4.3 (3) | $0.99 | Utilities |
| [VPD Vapor Pressure Calculator](https://appshunter.io/ios/app/vpd-vapor-pressure-calculator/id1586028655) | 2.6 (9) | Free | Utilities |
| [CopyAndPaste Manager](https://appshunter.io/ios/app/copyandpaste-manager/id6739459968) | 5.0 (1) | Free | Utilities |
| [Rocket Proxy for Shadowrocket](https://appshunter.io/ios/app/rocket-proxy-for-shadowrocket/id6785291194) | 5.0 (6) | Free | Utilities |

## More apps by Nicholas Hwang

- [The Plant Map \| Care Tracker](https://appshunter.io/ios/app/the-plant-map-care-tracker/id6743325138)
- [Mahjong Sifu](https://appshunter.io/ios/app/mahjong-sifu/id6779875831)

All apps by Nicholas Hwang: https://appshunter.io/developer/1802240669

## Related topics

[vpd tool](https://appshunter.io/ios/topics/vpd-tool) · [vpd chart](https://appshunter.io/ios/topics/vpd-chart)

---

*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-09-01.*