# e vs VPD Tool

The clearest difference is price: e at Free against VPD Tool's $0.49. e also leads on iOS requirement (13.0 vs 18.5). VPD Tool's advantage is update cadence (every 2 months vs every 33 months). On ads, in-app purchases and device support there is nothing between them.

e is free to download; VPD Tool costs $0.49 up front. Neither carries in-app purchases, so what you see is what you pay.

e ships an update every 33 months, VPD Tool every 2 months. The most recent releases landed on November 4, 2026 and October 30, 2026 respectively.

## The numbers

| Metric | e | VPD Tool |
| --- | --- | --- |
| Price | **Free** | $0.49 |
| Rating | — | **[5.0 (1 ratings)](https://appshunter.io/ios/app/vpd-tool/id6751213834/reviews)** |
| Number of ratings | — | **1** |
| Positive reviews | — | 100.0% of reviews |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 33 months | **Every 2 months** |
| Monetization | — | Paid |
| Size | 6 MB | 2 MB |
| Requires iOS | **13.0** | 18.5 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Rockwool International A/S](https://appshunter.io/developer/560117967) | [Nicholas Hwang](https://appshunter.io/developer/1802240669) |

## What reviewers say

### e

[App page](https://appshunter.io/ios/app/e-gro/id6476660626)

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


### VPD Tool

[App page](https://appshunter.io/ios/app/vpd-tool/id6751213834)

This utility app helps growers understand Vapor Pressure Deficit (VPD) for optimal plant growth. It features an interactive heatmap and stage presets to guide environmental adjustments. Calculations are performed on-device for privacy.

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

**Features:** macOS Compatibility, Vision Pro support

**In-app purchases:** none


## Frequently asked questions

### Is e free?

e is free to download, with no in-app purchases.

### Is VPD Tool free?

VPD Tool costs $0.49, with no in-app purchases.

### Do e or VPD Tool have ads?

Neither e nor VPD Tool shows ads.

### Which is updated more often, e or VPD Tool?

e ships an update every 33 months, and VPD Tool every 2 months. Most recently, e was updated on November 4, 2026 and VPD Tool on October 30, 2026.

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*Compared by [AppsHunter](https://appshunter.io/) from daily US App Store data. Review summaries are generated from verbatim App Store reviews.*