# Light Meter vs Mars Hydro

The clearest difference is rating: Light Meter at 4.5 against Mars Hydro's 2.6. Light Meter also leads on ratings volume (116 vs 34). Mars Hydro's advantage is in-app purchases (none vs 4) and update cadence (every 2 months vs every 10 months). On price, review sentiment, ads and device support there is nothing between them.

Both are free to download. Light Meter sells 4 in-app purchases, starting at $3.99 per month. Mars Hydro asks for nothing beyond the download.

Light Meter holds the better App Store score, 4.5 against 2.6. Both are backed by a comparable volume of ratings — 116 and 34 respectively. Written reviews point the same way: 33% of Light Meter's written reviews are positive against 27% of Mars Hydro's.

Light Meter ships an update every 10 months, Mars Hydro every 2 months. The most recent releases landed on November 3, 2026 and October 30, 2026 respectively.

## The numbers

| Metric | Light Meter | Mars Hydro |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.5 (116 ratings)](https://appshunter.io/ios/app/light-meter-lux-525-pro/id1636117065/reviews)** | [2.6 (34 ratings)](https://appshunter.io/ios/app/mars-hydro/id6479227564/reviews) |
| Number of ratings | **116** | 34 |
| Positive reviews | **33.3% of reviews** | 26.9% of reviews |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 10 months | **Every 2 months** |
| Monetization | Free with in-app purchases | **Free** |
| Size | 17 MB | 52 MB |
| Requires iOS | 15.5 | **15.0** |
| Devices | iPhone, iPod | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Andrey Ivankin](https://appshunter.io/developer/1615973131) | [MARS TRADING RCC, INC.](https://appshunter.io/developer/1726858942) |

## What reviewers say

### Light Meter

[App page](https://appshunter.io/ios/app/light-meter-lux-525-pro/id1636117065)

This app functions as a precise and user-friendly light meter using your phone's built-in sensors. It measures illuminance, color temperature, PPFD/PAR, DLI, and luminous flux in real-time. It also includes a calculator for various illumination parameters and allows sharing or saving of measurements.

**Highlights:** Real-time illuminance measurement, Color temperature measurement, PPFD/PAR and DLI calculation, Built-in illumination calculator, Share and save measurements, No additional equipment needed

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium Monthly Subscription | $3.99 | per month |
| Premium Monthly Subscription | $4.99 | per month |
| Premium Lifetime Subscription | $19.99 | one-time |
| Premium Lifetime Subscription | $29.99 | one-time |


### Mars Hydro

[App page](https://appshunter.io/ios/app/mars-hydro/id6479227564)

Control your smart grow system with this app. Manage LED lights, ventilation, and monitor environmental data like CO2, temperature, and humidity for optimal plant growth. Automate your entire grow kit to mimic natural conditions.

**Highlights:** LED light control with timers and simulation, Ventilation system management, Complete grow kit automation via iHub, Environmental data monitoring (CO2, temp, humidity, PPFD), Sunrise and sunset simulation

**In-app purchases:** none


## Frequently asked questions

### Is Light Meter free?

Light Meter is free to download, with in-app purchases available.

### Is Mars Hydro free?

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

### Which has better reviews, Light Meter or Mars Hydro?

Light Meter is rated higher. Light Meter averages 4.5 out of 5 from 116 ratings, while Mars Hydro averages 2.6 from 34 ratings.

### Do Light Meter or Mars Hydro have ads?

Neither Light Meter nor Mars Hydro shows ads.

### Which is updated more often, Light Meter or Mars Hydro?

Light Meter ships an update every 10 months, and Mars Hydro every 2 months. Most recently, Light Meter was updated on November 3, 2026 and Mars Hydro 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.*