# NPK Calculator vs i

The clearest difference is price: i at Free against NPK Calculator's $2.99. i also leads on rating (5.0 vs 3.3) and iOS requirement (11.0 vs 18.5). NPK Calculator's advantage is update cadence (monthly vs every 6 months) and ratings volume (8 vs 1). On ads, in-app purchases and device support there is nothing between them.

i is free to download; NPK Calculator costs $2.99 up front. Neither carries in-app purchases, so what you see is what you pay.

i holds the better App Store score, 5.0 against 3.3. That said, the two scores are not equally well evidenced: NPK Calculator has 8 ratings behind it against 1, so its average is the more settled of the two.

NPK Calculator ships an update monthly, i every 6 months. The most recent releases landed on October 26, 2026 and October 7, 2026 respectively.

## The numbers

| Metric | NPK Calculator | i |
| --- | --- | --- |
| Price | $2.99 | **Free** |
| Rating | [3.3 (8 ratings)](https://appshunter.io/ios/app/npk-calculator/id988554060/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/i-droponics/id1551871602/reviews)** |
| Number of ratings | **8** | 1 |
| Positive reviews | 33.3% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Monthly** | Every 6 months |
| Monetization | Paid | **Free** |
| Size | 3 MB | 90 MB |
| Requires iOS | 18.5 | **11.0** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Anton Simonov](https://appshunter.io/developer/988554059) | [Linnkr Inc.](https://appshunter.io/developer/1551871604) |

## What reviewers say

### NPK Calculator

[App page](https://appshunter.io/ios/app/npk-calculator/id988554060)

This app helps optimize fertilizer solutions for plants by calculating the correct ratios of macronutrients and micronutrients. It aims to save money, prevent nutrient imbalances, and improve nutrient uptake for healthier plant growth in hydroponics or soil.

**Highlights:** Optimizes macronutrient and micronutrient ratios, Database of fertilizers, Nutrition programs from experienced growers, Saves money on fertilizer solutions, Prevents fertilizer burns and nutrient lock-out, Optimizes nutrient uptake

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

**In-app purchases:** none


### i

[App page](https://appshunter.io/ios/app/i-droponics/id1551871602)

This app guides users through routine operations for a specific hydroponic system. It offers growing guides, scheduling, fertilization advice, record-keeping, and troubleshooting to support daily, weekly, and periodic tasks. It's designed for owners of the TAPKIT system.

**Highlights:** Growing guides, Scheduling and notifications, Fertilization advice, Record keeping and analysis, Troubleshooting system, Instructional videos, Real-time sensor alerts

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is NPK Calculator free?

NPK Calculator costs $2.99, with no in-app purchases.

### Is i free?

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

### Which has better reviews, NPK Calculator or i?

i is rated higher. NPK Calculator averages 3.3 out of 5 from 8 ratings, while i averages 5.0 from 1 ratings.

### Do NPK Calculator or i have ads?

Neither NPK Calculator nor i shows ads.

### Which is updated more often, NPK Calculator or i?

NPK Calculator ships an update monthly, and i every 6 months. Most recently, NPK Calculator was updated on October 26, 2026 and i on October 7, 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.*