# HydroCalc Plus vs Datum

The clearest difference is price: Datum at Free against HydroCalc Plus's $6.99. On rating, ratings volume, update cadence and ads there is nothing between them.

Datum is free to download; HydroCalc Plus costs $6.99 up front. HydroCalc Plus sells 4 one-off in-app purchases and Datum sells 2 in-app purchases, starting at $2.99 per 7 days. Whichever you choose, the download price is not the number that matters.

On the App Store both sit at effectively the same score — 5.0 for HydroCalc Plus against 5.0 for Datum. Both are backed by a comparable volume of ratings — 1 and 1 respectively.

HydroCalc Plus ships an update every 3 weeks, Datum fortnightly. The most recent releases landed on October 23, 2026 and October 14, 2026 respectively.

## The numbers

| Metric | HydroCalc Plus | Datum |
| --- | --- | --- |
| Price | $6.99 | **Free** |
| Rating | [5.0 (1 ratings)](https://appshunter.io/ios/app/hydrocalc-plus/id578807688/reviews) | [5.0 (1 ratings)](https://appshunter.io/ios/app/datum-sex-frequency-tracker/id6757833922/reviews) |
| Number of ratings | 1 | 1 |
| Positive reviews | 100.0% of reviews | — |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 3 weeks | **Fortnightly** |
| Monetization | Paid | **Free with in-app purchases** |
| Size | 34 MB | 60 MB |
| Requires iOS | 15.1 | 15.1 |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Age rating | 4+ | 17+ |
| Developer | [Transparent Blue Water LLC](https://appshunter.io/developer/1847968351) | [Scale9dev](https://appshunter.io/developer/1861605142) |

## What reviewers say

### HydroCalc Plus

[App page](https://appshunter.io/ios/app/hydrocalc-plus/id578807688)

A professional tool for hydraulic engineers to calculate pressure losses in piping systems. It supports US and SI units, offers an extensive pipe material and fittings database, and includes inverse calculations for design optimization.

**Highlights:** Friction head loss calculation (Hazen-Williams), US and SI unit support, Extensive pipe material library, Fittings and valves database, Inverse calculation mode, Real-time results (velocity, losses)

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

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Pump Power Calculator | $1.99 | one-time |
| System Curve Generator | $1.99 | one-time |
| Pipe Database | $1.99 | one-time |
| Industrial Fluids Pack | $2.99 | one-time |


### Datum

[App page](https://appshunter.io/ios/app/datum-sex-frequency-tracker/id6757833922)

This app provides clear numbers and simple insights into your intimate life, helping you understand your real patterns over time. Log encounters easily, track streaks and consistency, and view monthly and yearly trends with a private, data-driven approach.

**Highlights:** Intimacy frequency tracking, Streak and consistency monitoring, Monthly and yearly trend analysis, Long-term pattern visualization, One-tap encounter logging, Optional notes for entries, Private data storage

**Features:** macOS Compatibility

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Datum Pro Weekly | $2.99 | per 7 days |
| Datum Pro Yearly | $29.99 | per year |


## Frequently asked questions

### Is HydroCalc Plus free?

HydroCalc Plus costs $6.99, and also offers in-app purchases.

### Is Datum free?

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

### Which has better reviews, HydroCalc Plus or Datum?

HydroCalc Plus and Datum are both rated 5.0 out of 5 on the App Store, from 1 and 1 ratings respectively.

### Do HydroCalc Plus or Datum have ads?

Neither HydroCalc Plus nor Datum shows ads.

### Which is updated more often, HydroCalc Plus or Datum?

HydroCalc Plus ships an update every 3 weeks, and Datum fortnightly. Most recently, HydroCalc Plus was updated on October 23, 2026 and Datum on October 14, 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.*