# FDR Calculator vs GDDTracker

The clearest difference is review sentiment: GDDTracker at 100% against FDR Calculator's 0%. GDDTracker also leads on update cadence (every 2 days vs every 4 months). FDR Calculator's advantage is monetization model (free with in-app purchases vs subscription) and iOS requirement (15.0 vs 17.6). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. FDR Calculator sells 2 in-app purchases, starting at $1.99 per month and GDDTracker sells 2 in-app purchases, starting at $0.99 per month. Whichever you choose, the download price is not the number that matters.

FDR Calculator ships an update every 4 months, GDDTracker every 2 days. The most recent releases landed on October 23, 2026 and October 25, 2026 respectively.

## The numbers

| Metric | FDR Calculator | GDDTracker |
| --- | --- | --- |
| Price | Free | Free |
| Rating | — | **[4.7 (13 ratings)](https://appshunter.io/ios/app/gddtracker/id6752981800/reviews)** |
| Number of ratings | — | **13** |
| Positive reviews | 0.0% of reviews | **100.0% of reviews** |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 4 months | **Every 2 days** |
| Monetization | **Free with in-app purchases** | Subscription |
| Size | 35 MB | 15 MB |
| Requires iOS | **15.0** | 17.6 |
| Devices | **iPhone, iPad, iPod** | iPhone, Apple Watch |
| Age rating | 4+ | 4+ |
| Developer | [Alan Richert](https://appshunter.io/developer/527055673) | [Kirk Faris](https://appshunter.io/developer/1842027731) |

## What reviewers say

### FDR Calculator

[App page](https://appshunter.io/ios/app/fdr-calculator/id527055670)

Instantly calculate fire danger ratings with professional-grade algorithms. Offers real-time weather data integration, visual danger level displays, and detailed action recommendations for informed fire prevention and management.

**Highlights:** Instant Fire Danger Index calculations, Real-time weather data integration, Visual color-coded danger levels, Detailed action recommendations, Manual calculator for offline use, Automatic location detection

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Weather Pro (Monthly) | $1.99 | per month |
| Enable Local Weather | Free | one-time |


### GDDTracker

[App page](https://appshunter.io/ios/app/gddtracker/id6752981800)

This app calculates Growing Degree Days (GDD) using hyper-local weather data to help you precisely time lawn care applications. It also logs applications, provides smart reminders, and includes profiles for over 50 grass varieties.

**Highlights:** Growing Degree Day (GDD) calculation and forecasting, Application logging with product details and notes, Smart reminders based on GDD, days, or soil temp, 50+ grass variety profiles, Rate calculator for product amounts, Multiple lawn management, CSV/PDF record export

**Features:** Apple Watch app

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Monthly | $0.99 | per month |
| Annual | $9.99 | per year |


## Frequently asked questions

### Is FDR Calculator free?

FDR Calculator is free to download, with in-app purchases available.

### Is GDDTracker free?

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

### Do FDR Calculator or GDDTracker have ads?

Neither FDR Calculator nor GDDTracker shows ads.

### Which is updated more often, FDR Calculator or GDDTracker?

FDR Calculator ships an update every 4 months, and GDDTracker every 2 days. Most recently, FDR Calculator was updated on October 23, 2026 and GDDTracker on October 25, 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.*