# Dri vs BookMPG

The clearest difference is update cadence: BookMPG at every 8 days against Dri's every 13 months. Dri's advantage is iOS requirement (13.0 vs 15.0). On price, ads, in-app purchases and device support there is nothing between them.

Both are free to download. Neither carries in-app purchases, so what you see is what you pay.

Dri ships an update every 13 months, BookMPG every 8 days. The most recent releases landed on October 9, 2026 and October 30, 2026 respectively.

## The numbers

| Metric | Dri | BookMPG |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[3.6 (12 ratings)](https://appshunter.io/ios/app/dri-eaz-psychrometric-calc/id484266596/reviews)** | — |
| Number of ratings | **12** | — |
| Positive reviews | 62.5% of reviews | — |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | Every 13 months | **Every 8 days** |
| Monetization | Free | — |
| Size | 4 MB | 96 MB |
| Requires iOS | **13.0** | 15.0 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Legend Brands](https://appshunter.io/developer/484266599) | [Jabez Software, Llc](https://appshunter.io/developer/1047275178) |

## What reviewers say

### Dri

[App page](https://appshunter.io/ios/app/dri-eaz-psychrometric-calc/id484266596)

This utility app calculates essential drying environment variables. Input temperature and relative humidity to instantly get grains per pound (GPP). Advanced options allow calculation of vapor pressure and air dew point to material, with easy term definitions.

**Highlights:** Calculate grains per pound (GPP), Calculate vapor pressure, Calculate air dew point to material, Switch between F° and C°, Easy-access term definitions

**Features:** macOS Compatibility

**In-app purchases:** none


### BookMPG

[App page](https://appshunter.io/ios/app/bookmpg/id6478734288)

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

**In-app purchases:** none


## Frequently asked questions

### Is Dri free?

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

### Is BookMPG free?

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

### Do Dri or BookMPG have ads?

Neither Dri nor BookMPG shows ads.

### Which is updated more often, Dri or BookMPG?

Dri ships an update every 13 months, and BookMPG every 8 days. Most recently, Dri was updated on October 9, 2026 and BookMPG 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.*