# SANlight vs VPD Chart

The clearest difference is in-app purchases: SANlight at none against VPD Chart's 2. VPD Chart's advantage is update cadence (every 3 weeks vs every 6 months). On price, ads, device support and iOS requirement there is nothing between them.

Both are free to download. VPD Chart sells 2 in-app purchases, starting at $3.99 per month. SANlight asks for nothing beyond the download.

SANlight ships an update every 6 months, VPD Chart every 3 weeks. The most recent releases landed on September 23, 2026 and September 22, 2026 respectively.

## The numbers

| Metric | SANlight | VPD Chart |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.5 (30 ratings)](https://appshunter.io/ios/app/vpd-chart/id6470015847/reviews)** |
| Number of ratings | — | **30** |
| Positive reviews | — | 73.7% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 6 months | **Every 3 weeks** |
| Monetization | — | Free with in-app purchases |
| Size | 32 MB | 49 MB |
| Requires iOS | **14.0** | 15.1 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Martin Anker](https://appshunter.io/developer/1658513710) | [INNOVO DEV S.R.L.](https://appshunter.io/developer/1814828527) |

## What reviewers say

### SANlight

[App page](https://appshunter.io/ios/app/sanlight/id1658513708)

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

**In-app purchases:** none


### VPD Chart

[App page](https://appshunter.io/ios/app/vpd-chart/id6470015847)

This app calculates Vapor Pressure Deficit (VPD) using air temperature, relative humidity, and canopy temperature. It offers real-time charting, sensor integration, and educational tools to understand plant growth environments. Organize data by zones and visualize dew point areas.

**Highlights:** VPD calculation, Interactive VPD chart, Sensor integration, Zone organization, Dew point visualization, Grow Timeline

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| VPD Chart Plus (monthly) | $3.99 | per month |
| VPD Chart Plus (annual) | $29.99 | per year |


## Frequently asked questions

### Is SANlight free?

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

### Is VPD Chart free?

VPD Chart is free to download, with in-app purchases available.

### Do SANlight or VPD Chart have ads?

Neither SANlight nor VPD Chart shows ads.

### Which is updated more often, SANlight or VPD Chart?

SANlight ships an update every 6 months, and VPD Chart every 3 weeks. Most recently, SANlight was updated on September 23, 2026 and VPD Chart on September 22, 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.*