# uSpectrumX vs PPFD METER

The clearest difference is in-app purchases: uSpectrumX at none against PPFD METER's 3. uSpectrumX also leads on ads (none vs shown) and iOS requirement (9.0 vs 18.0). PPFD METER's advantage is update cadence (every 3 weeks vs every 3 months). On price and device support there is nothing between them.

Both are free to download. PPFD METER sells 3 in-app purchases, starting at $1.99 per month. uSpectrumX asks for nothing beyond the download.

uSpectrumX ships an update every 3 months, PPFD METER every 3 weeks. The most recent releases landed on September 16, 2026 and September 22, 2026 respectively.

## The numbers

| Metric | uSpectrumX | PPFD METER |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.6 (118 ratings)](https://appshunter.io/ios/app/ppfd-meter-grow-light-meter/id6479329051/reviews)** |
| Number of ratings | — | **118** |
| Positive reviews | — | 52.6% of reviews |
| In-app purchases | **No** | Yes |
| Ads | **No** | Yes |
| Update frequency | Every 3 months | **Every 3 weeks** |
| Monetization | — | Free with in-app purchases |
| Size | 25 MB | 43 MB |
| Requires iOS | **9.0** | 18.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [United Power Research Technology Corporation](https://appshunter.io/developer/1501316337) | [Candas Pamukcu](https://appshunter.io/developer/1735587895) |

## What reviewers say

### uSpectrumX

[App page](https://appshunter.io/ios/app/uspectrumx/id1318581445)

**Features:** macOS Compatibility

**In-app purchases:** none


### PPFD METER

[App page](https://appshunter.io/ios/app/ppfd-meter-grow-light-meter/id6479329051)

This app measures light intensity for plants, converting LUX to PPFD and DLI. It offers advanced light mapping, uniformity analysis, and efficiency insights to optimize plant growth. Customize profiles for different environments and growth stages.

**Highlights:** LUX, PPFD, DLI, and PAR measurements, Light mapping and distribution analysis, Uniformity and PPF evaluation, Energy efficiency and consumption tracking, Customizable setting profiles, Bluetooth sensor integration

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium | $1.99 | per month |
| Premium Plus | $2.99 | per month |
| Remove Ads | $29.99 | one-time |


## Frequently asked questions

### Is uSpectrumX free?

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

### Is PPFD METER free?

PPFD METER is free to download, with in-app purchases available.

### Do uSpectrumX or PPFD METER have ads?

PPFD METER shows ads; uSpectrumX does not.

### Which is updated more often, uSpectrumX or PPFD METER?

uSpectrumX ships an update every 3 months, and PPFD METER every 3 weeks. Most recently, uSpectrumX was updated on September 16, 2026 and PPFD METER 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.*