# HydroCalc Basic vs SpecPad

The clearest difference is iOS requirement: HydroCalc Basic at 15.1 against SpecPad's 18.0. On price, update cadence, ads and in-app purchases there is nothing between them.

Both are free to download. HydroCalc Basic sells 1 one-off in-app purchase and SpecPad sells 3 in-app purchases, starting at $2.99 per month. Whichever you choose, the download price is not the number that matters.

HydroCalc Basic ships an update every 11 days, SpecPad every 10 days. The most recent releases landed on October 4, 2026 and October 1, 2026 respectively.

## The numbers

| Metric | HydroCalc Basic | SpecPad |
| --- | --- | --- |
| Price | Free | Free |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | Every 11 days | **Every 10 days** |
| Size | 35 MB | 19 MB |
| Requires iOS | **15.1** | 18.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Transparent Blue Water LLC](https://appshunter.io/developer/1847968351) | [John Steinmetz](https://appshunter.io/developer/1881750415) |

## What reviewers say

### HydroCalc Basic

[App page](https://appshunter.io/ios/app/hydrocalc-basic/id6752577110)

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

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Premium - Flow Units & Ad-Free | $1.99 | one-time |


### SpecPad

[App page](https://appshunter.io/ios/app/specpad/id6787570085)

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| SpecPad Pro - Monthly | $2.99 | per month |
| SpecPad Pro - Yearly | $17.99 | per year |
| SpecPad Pro - Lifetime | $29.99 | one-time |


## Frequently asked questions

### Is HydroCalc Basic free?

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

### Is SpecPad free?

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

### Do HydroCalc Basic or SpecPad have ads?

Neither HydroCalc Basic nor SpecPad shows ads.

### Which is updated more often, HydroCalc Basic or SpecPad?

HydroCalc Basic ships an update every 11 days, and SpecPad every 10 days. Most recently, HydroCalc Basic was updated on October 4, 2026 and SpecPad on October 1, 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.*