# Plumbing Formulator vs InSight Countdown

The clearest difference is in-app purchases: InSight Countdown at none against Plumbing Formulator's 4. InSight Countdown also leads on update cadence (monthly vs every 2 months). Plumbing Formulator's advantage is iOS requirement (18.6 vs 26.0). On price, ads and device support there is nothing between them.

Both are free to download. Plumbing Formulator sells 4 one-off in-app purchases. InSight Countdown asks for nothing beyond the download.

Plumbing Formulator ships an update every 2 months, InSight Countdown monthly. The most recent releases landed on September 26, 2026 and September 9, 2026 respectively.

## The numbers

| Metric | Plumbing Formulator | InSight Countdown |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.6 (7 ratings)](https://appshunter.io/ios/app/plumbing-formulator/id303497783/reviews)** | — |
| Number of ratings | **7** | — |
| Positive reviews | 9.1% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | Every 2 months | **Monthly** |
| Monetization | Free | — |
| Size | 123 MB | 9 MB |
| Requires iOS | **18.6** | 26.0 |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | 4+ | 12+ |
| Developer | [Historycentral.com](https://appshunter.io/developer/1744330560) | [Aliaksandr Harbavets](https://appshunter.io/developer/1787084561) |

## What reviewers say

### Plumbing Formulator

[App page](https://appshunter.io/ios/app/plumbing-formulator/id303497783)

This professional calculator app provides over 200 formulas, calculators, and reference materials for plumbers, HVAC technicians, and mechanical contractors. It covers a wide range of calculations for water flow, piping, drainage, water heaters, pumps, and more, all in one pocket-sized tool.

**Highlights:** Over 200 formulas and calculators, Water flow and supply calculations, Pipe and piping calculations, Drainage and venting calculations, Water heater and pump calculations, Reference charts and code books, Pipe cut list optimizer

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

**In-app purchases (4)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Pro Version | $1.99 | one-time |
| Pro Purchase | $3.99 | one-time |
| Starter | $5.99 | one-time |
| Growth | $9.99 | one-time |


### InSight Countdown

[App page](https://appshunter.io/ios/app/insight-countdown/id6783735098)

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

**In-app purchases:** none


## Frequently asked questions

### Is Plumbing Formulator free?

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

### Is InSight Countdown free?

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

### Do Plumbing Formulator or InSight Countdown have ads?

Neither Plumbing Formulator nor InSight Countdown shows ads.

### Which is updated more often, Plumbing Formulator or InSight Countdown?

Plumbing Formulator ships an update every 2 months, and InSight Countdown monthly. Most recently, Plumbing Formulator was updated on September 26, 2026 and InSight Countdown on September 9, 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.*