# CRSI Rebar Reference vs calc318

The clearest difference is review sentiment: calc318 at 100% against CRSI Rebar Reference's 33%. calc318 also leads on rating (5.0 vs 3.3). CRSI Rebar Reference's advantage is monetization model (free vs subscription) and ratings volume (16 vs 1). On price, ads and in-app purchases there is nothing between them.

Both are free to download. CRSI Rebar Reference sells 3 one-off in-app purchases and calc318 sells 2 in-app purchases, starting at $2.99 per month. Whichever you choose, the download price is not the number that matters.

calc318 holds the better App Store score, 5.0 against 3.3. That said, the two scores are not equally well evidenced: CRSI Rebar Reference has 16 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 33% of CRSI Rebar Reference's written reviews are positive against 100% of calc318's.

CRSI Rebar Reference ships an update every 5 weeks, calc318 every 3 months. The most recent releases landed on October 21, 2026 and October 1, 2026 respectively.

## The numbers

| Metric | CRSI Rebar Reference | calc318 |
| --- | --- | --- |
| Price | Free | Free |
| Rating | [3.3 (16 ratings)](https://appshunter.io/ios/app/crsi-rebar-reference/id1423271565/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/calc318/id6763030413/reviews)** |
| Number of ratings | **16** | 1 |
| Positive reviews | 33.3% of reviews | **100.0% of reviews** |
| In-app purchases | Yes | Yes |
| Ads | No | No |
| Update frequency | **Every 5 weeks** | Every 3 months |
| Monetization | **Free** | Subscription |
| Size | 51 MB | 19 MB |
| Requires iOS | **15.1** | 26.0 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 17+ | 4+ |
| Developer | [Concrete Reinforcing Steel Institute](https://appshunter.io/developer/1423271564) | [ARTIFICIAL INTELLIGENCE OPTIMIZATION AND SOFTWARE AIOS LLC](https://appshunter.io/developer/1835191566) |

## What reviewers say

### CRSI Rebar Reference

[App page](https://appshunter.io/ios/app/crsi-rebar-reference/id1423271565)

Access essential data for reinforcing bars (rebar) including specifications, hook details, and marking requirements. This app serves as a quick reference for industry standards and links to online resources.

**Highlights:** ASTM standard reinforcing bar specifications, Standard hook details (90, 135, 180 degrees), Stirrup/tie hook details, ASTM reinforcing bar marking requirements, Minimum yield and tensile requirements, Links to CRSI online resources

**Features:** macOS Compatibility

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| CRSI - Rebar Identifier Module | $2.99 | one-time |
| CRSI Development Length ACI | $4.99 | one-time |
| CRSI Development length AASHTO | $4.99 | one-time |


### calc318

[App page](https://appshunter.io/ios/app/calc318/id6763030413)

Instantly solve 175 ACI 318-19 equations with live computation and interactive charts. Understand equation behavior with sensitivity graphs and clear variable descriptions. Designed for engineers needing quick, accurate calculations and insights.

**Highlights:** 175 ACI 318-19 equations solved instantly, Live computation with unit awareness, Interactive sensitivity graphs, Professionally formatted equations, Complete variable descriptions, Smart search functionality, Recents tab for quick access

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

**In-app purchases (2)**

| Purchase | Price | Billing |
| --- | --- | --- |
| calc318 Pro Monthly | $2.99 | per month |
| calc318 Pro Yearly | $12.99 | per year |


## Frequently asked questions

### Is CRSI Rebar Reference free?

CRSI Rebar Reference is free to download, with in-app purchases available.

### Is calc318 free?

calc318 is free to download, with in-app purchases available.

### Which has better reviews, CRSI Rebar Reference or calc318?

calc318 is rated higher. CRSI Rebar Reference averages 3.3 out of 5 from 16 ratings, while calc318 averages 5.0 from 1 ratings.

### Do CRSI Rebar Reference or calc318 have ads?

Neither CRSI Rebar Reference nor calc318 shows ads.

### Which is updated more often, CRSI Rebar Reference or calc318?

CRSI Rebar Reference ships an update every 5 weeks, and calc318 every 3 months. Most recently, CRSI Rebar Reference was updated on October 21, 2026 and calc318 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.*