e vs VPD Tool
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
e
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The e-Gro app provides rootzone information that puts you in the driver’s seat. The reliable platform paired with our high-quality sensors enable you to monitor and steer your crops. View sensor data from all rooms in your facility and monitor key measurements such as EC, WC, room temperatures and relative humidity. Powered by Grodan
VPD Tool
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.
- Interactive VPD heatmap
- Stage-specific VPD ranges
- Leaf and Air VPD calculation
- Home and Lock Screen widgets
- On-device calculations
- CSV log export
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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
Screenshots
Verdict
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.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
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.
| Parameter | e | VPD Tool |
|---|---|---|
| Price | Free — better | $0.49 |
| Rating | — | 5.0 (1 ratings) — better |
| Positive reviews | — | 100.0% of reviews |
| Number of ratings | — | 1 — better |
| Update frequency | Every 33 months | Every 2 months — better |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | — | Paid |
| Devices | iPhone, iPad, iPod — better | iPhone, iPad |
| Requires iOS | 13.0 — better | 18.5 |
| Further details — not scored | ||
| Size | 6 MB | 2 MB |
| Age rating | 4+ | 4+ |
| Developer | Rockwool International A/S | Nicholas Hwang |
In-app purchases
e
No in-app purchases
VPD Tool
No in-app purchases
