# Hydrology Formulator vs TDH Calculator

The clearest difference is in-app purchases: TDH Calculator at none against Hydrology Formulator's 1. TDH Calculator also leads on iOS requirement (7.0 vs 18.6). On price, ads and device support there is nothing between them.

Both are free to download. Hydrology Formulator sells 1 one-off in-app purchase. TDH Calculator asks for nothing beyond the download.

## The numbers

| Metric | Hydrology Formulator | TDH Calculator |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (1 ratings)](https://appshunter.io/ios/app/hydrology-formulator/id346512904/reviews)** | — |
| Number of ratings | **1** | — |
| Positive reviews | 0.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 6 months | — |
| Monetization | Free | — |
| Size | 18 MB | 1 MB |
| Requires iOS | 18.6 | **7.0** |
| Devices | iPhone, iPad | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Historycentral.com](https://appshunter.io/developer/1744330560) | [Jeffrey Iverson](https://appshunter.io/developer/880898146) |

## What reviewers say

### Hydrology Formulator

[App page](https://appshunter.io/ios/app/hydrology-formulator/id346512904)

This app provides a comprehensive collection of over 1,000 formulas, calculators, and conversions for hydrology and civil engineering. It covers a wide range of topics including groundwater, stormwater, pipe flow, and water pollution.

**Highlights:** 1,000+ formulas and calculators, Groundwater analysis tools, Stormwater design calculations, Open channel and pipe flow equations, Water pollution modeling, Conversions and reference data

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Pro Version | $3.99 | one-time |


### TDH Calculator

[App page](https://appshunter.io/ios/app/tdh-calculator/id880898143)

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Hydrology Formulator free?

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

### Is TDH Calculator free?

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

### Do Hydrology Formulator or TDH Calculator have ads?

Neither Hydrology Formulator nor TDH Calculator shows ads.

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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.*