# PrerAp vs Concrete & Stair Calculator

The clearest difference is review sentiment: Concrete & Stair Calculator at 100% against PrerAp's 0%. Concrete & Stair Calculator also leads on update cadence (every 5 weeks vs every 5 months). PrerAp's advantage is in-app purchases (none vs 3) and iOS requirement (12.0 vs 15.0). On price, ads and device support there is nothing between them.

Both are free to download. Concrete & Stair Calculator sells 3 in-app purchases, starting at $2.99 per month. PrerAp asks for nothing beyond the download.

PrerAp ships an update every 5 months, Concrete & Stair Calculator every 5 weeks. The most recent releases landed on October 7, 2026 and October 28, 2026 respectively.

## The numbers

| Metric | PrerAp | Concrete & Stair Calculator |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[4.5 (2 ratings)](https://appshunter.io/ios/app/prerap/id1660054792/reviews)** | — |
| Number of ratings | **2** | — |
| Positive reviews | 0.0% of reviews | **100.0% of reviews** |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 5 months | **Every 5 weeks** |
| Monetization | **Free** | Freemium |
| Size | 29 MB | 42 MB |
| Requires iOS | **12.0** | 15.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPod |
| Age rating | 4+ | 4+ |
| Developer | [Evolve (RDC)](https://appshunter.io/developer/1567017217) | [Devolim](https://appshunter.io/developer/1823631894) |

## What reviewers say

### PrerAp

[App page](https://appshunter.io/ios/app/prerap/id1660054792)

This app allows voters to securely store their biographical information and generate QR codes. These codes can then be scanned during enrollment to quickly retrieve data, significantly reducing wait times at registration centers.

**Highlights:** Biographical data storage, QR code generation, Reduced registration time, Data retrieval via scanning

**Features:** macOS Compatibility

**In-app purchases:** none


### Concrete & Stair Calculator

[App page](https://appshunter.io/ios/app/concrete-and-stair-calculator/id6766280669)

This app provides over 70 construction trade calculations, displaying results in 3D with dimensions. It adapts to local units and rules, offering an AI assistant for job site questions. Organize calculations by project for easy access.

**Highlights:** 70+ trade calculations, 3D result visualizations, AI job site assistant (Pro), Offline calculations, Project organization, Unit and rule adaptation

**Features:** macOS Compatibility, Family Sharing

**In-app purchases (3)**

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


## Frequently asked questions

### Is PrerAp free?

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

### Is Concrete & Stair Calculator free?

Concrete & Stair Calculator is free to download, with in-app purchases available.

### Do PrerAp or Concrete & Stair Calculator have ads?

Neither PrerAp nor Concrete & Stair Calculator shows ads.

### Which is updated more often, PrerAp or Concrete & Stair Calculator?

PrerAp ships an update every 5 months, and Concrete & Stair Calculator every 5 weeks. Most recently, PrerAp was updated on October 7, 2026 and Concrete & Stair Calculator on October 28, 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.*