# Plumbing Formulator vs Navisizer

The clearest difference is rating: Plumbing Formulator at 4.6 against Navisizer's 2.4. Navisizer's advantage is in-app purchases (none vs 4) and ratings volume (26 vs 7). On price, review sentiment, update cadence and ads there is nothing between them.

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

Plumbing Formulator holds the better App Store score, 4.6 against 2.4. Both are backed by a comparable volume of ratings — 7 and 26 respectively. Written reviews complicate that: 9% of Plumbing Formulator's written reviews are positive against 13% of Navisizer's, so the app with the better star average is not the one people write more warmly about.

Plumbing Formulator ships an update every 2 months, Navisizer every 4 months. The most recent releases landed on August 23, 2026 and June 1, 2026 respectively.

## The numbers

| Metric | Plumbing Formulator | Navisizer |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.6 (7 ratings)](https://appshunter.io/ios/app/plumbing-formulator/id303497783/reviews)** | [2.4 (26 ratings)](https://appshunter.io/ios/app/navisizer/id1327385997/reviews) |
| Number of ratings | 7 | **26** |
| Positive reviews | 9.1% of reviews | **12.5% of reviews** |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 2 months** | Every 4 months |
| Monetization | Free | Free |
| Size | 123 MB | 21 MB |
| Requires iOS | 18.6 | **17.2** |
| Devices | iPhone, iPad | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Historycentral.com](https://appshunter.io/developer/1744330560) | [Navien, Inc.](https://appshunter.io/developer/1327385996) |

## 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 |


### Navisizer

[App page](https://appshunter.io/ios/app/navisizer/id1327385997)

This app helps size domestic hot water heating systems for residential and commercial use. It calculates operating costs, savings, and generates comprehensive job specifications for Navien NPE Series tankless water heaters.

**Highlights:** Residential system sizing, Operating cost and savings calculation, Commercial application sizing (ASHRAE Hunter Curve), Tankless and tankless with storage solutions, Comprehensive job specification output, Save, print, or email system specs

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Plumbing Formulator free?

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

### Is Navisizer free?

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

### Which has better reviews, Plumbing Formulator or Navisizer?

Plumbing Formulator is rated higher. Plumbing Formulator averages 4.6 out of 5 from 7 ratings, while Navisizer averages 2.4 from 26 ratings.

### Do Plumbing Formulator or Navisizer have ads?

Neither Plumbing Formulator nor Navisizer shows ads.

### Which is updated more often, Plumbing Formulator or Navisizer?

Plumbing Formulator ships an update every 2 months, and Navisizer every 4 months. Most recently, Plumbing Formulator was updated on August 23, 2026 and Navisizer on June 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.*