# ProjectorCalc vs Ambulance Siren

The clearest difference is price: Ambulance Siren at Free against ProjectorCalc's $2.99. Ambulance Siren also leads on iOS requirement (6.0 vs 9.2). ProjectorCalc's advantage is rating (5.0 vs 1.7) and review sentiment (38% vs 0%). On ratings volume, update cadence, ads and device support there is nothing between them.

Ambulance Siren is free to download; ProjectorCalc costs $2.99 up front. Ambulance Siren sells 1 one-off in-app purchase. ProjectorCalc asks for nothing beyond the download.

ProjectorCalc holds the better App Store score, 5.0 against 1.7. Both are backed by a comparable volume of ratings — 2 and 3 respectively. Written reviews point the same way: 38% of ProjectorCalc's written reviews are positive against 0% of Ambulance Siren's.

ProjectorCalc ships an update every 49 months, Ambulance Siren every 25 months. The most recent releases landed on October 31, 2026 and November 1, 2026 respectively.

## The numbers

| Metric | ProjectorCalc | Ambulance Siren |
| --- | --- | --- |
| Price | $2.99 | **Free** |
| Rating | **[5.0 (2 ratings)](https://appshunter.io/ios/app/projectorcalc/id310342928/reviews)** | [1.7 (3 ratings)](https://appshunter.io/ios/app/ambulance-siren/id918368889/reviews) |
| Number of ratings | 2 | **3** |
| Positive reviews | **37.5% of reviews** | 0.0% of reviews |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 49 months | **Every 25 months** |
| Monetization | Paid | **Free with in-app purchases** |
| Size | 10 MB | 12 MB |
| Requires iOS | 9.2 | **6.0** |
| Devices | iPhone, iPod | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [D!HV Lighting](https://appshunter.io/developer/287079053) | [IGEARS TECHNOLOGY LTD](https://appshunter.io/developer/399977420) |

## What reviewers say

### ProjectorCalc

[App page](https://appshunter.io/ios/app/projectorcalc/id310342928)

This utility app helps lighting technicians and projectionists calculate projected image dimensions. It determines image width, height, diagonal length, brightness, area, and pixel density based on projector and location details. It also estimates keystone distortion.

**Highlights:** Calculate image width, height, and diagonal length, Determine brightness in Nits, Calculate total projected area, Compute pixels per inch, Estimate keystone distortion

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

**In-app purchases:** none


### Ambulance Siren

[App page](https://appshunter.io/ios/app/ambulance-siren/id918368889)

This app provides realistic ambulance siren sounds and lighting effects for entertainment. It can be used for pranks or as a novelty alarm. Explore various sound options and light patterns for fun.

**Highlights:** Ambulance siren sound effects, Lighting effects, Alarm function, Tricky sound options, Soundboard for pranks

**Features:** macOS Compatibility

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Remove Advertisements | $0.99 | one-time |


## Frequently asked questions

### Is ProjectorCalc free?

ProjectorCalc costs $2.99, with no in-app purchases.

### Is Ambulance Siren free?

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

### Which has better reviews, ProjectorCalc or Ambulance Siren?

ProjectorCalc is rated higher. ProjectorCalc averages 5.0 out of 5 from 2 ratings, while Ambulance Siren averages 1.7 from 3 ratings.

### Do ProjectorCalc or Ambulance Siren have ads?

Neither ProjectorCalc nor Ambulance Siren shows ads.

### Which is updated more often, ProjectorCalc or Ambulance Siren?

ProjectorCalc ships an update every 49 months, and Ambulance Siren every 25 months. Most recently, ProjectorCalc was updated on October 31, 2026 and Ambulance Siren on November 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.*