Comparison

CRSI Rebar Reference vs calc318

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

CRSI Rebar Reference

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
Read full description

QUICK REFERENCE! This ready reference app from the Concrete Reinforcing Steel Institute is a handy desk and field resource and includes information on ASTM standard reinforcing bars (rebar), standard hook details, standard stirrup/tie hook details, and ASTM reinforcing bar marking requirements. The app provides standard rebar specifications including sizes, diameters, areas and weights along with 90-, 135- and 180-degree hook details. Minimum yield and minimum tensile requirements per ASTM are also included. Industry standard bar markings for inch-pound rebar is illustrated for grades 40, 50, 60, 75, 80, 100 (A615), 100 (A1035), and 120. Links to the CRSI’s online resources are included.

About

calc318

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
Read full description

Solve all 175 equations from ACI 318-19 Appendix C, instantly, in US Customary Units. Calc318 turns the equations from ACI 318-19 Appendix C into a live calculator. Pick an equation, enter your parameters, and get an answer the moment you type — beautifully rendered, with every variable clearly defined and unit-aware. No spreadsheets, no hand calcs. calc318 requires an auto-renewable subscription. Start your 7-day free trial — no charge until the trial ends, and you can cancel anytime. After the trial, your subscription continues at $12.99/year or $2.99/month. Manage or cancel anytime in Settings → Apple ID → Subscriptions. See more than just a number. Tap any input to open an interactive chart that shows exactly how your result responds as that parameter changes — with a draggable point and a family of curves for the other key variables, so you understand the behavior of the equation, not just one data point. FEATURES: - Live computation for all 175 ACI 318-19 equations, fully unit-aware. - Professionally formatted equations with LaTeX-quality rendering. - Interactive sensitivity graphs — drag a point and watch the result update in real time. - Compare curves across multiple parameter values to see trends at a glance. - Complete variable descriptions and units for every input. - Smart search by section number, chapter, keyword, or variable. - Recents tab to jump back to equations you use most. - Clean, intuitive interface designed for engineers. Whether you're checking a calculation, running a quick sensitivity study, or referencing design provisions, calc318 gets you the answer — and the insight behind it — in seconds. Privacy Policy: https://aiosciv.com/calc318/ Terms of Use (EULA): http://www.apple.com/legal/itunes/appstore/dev/stdeula

Screenshots

CRSI Rebar Reference4 screens
calc3184 screens

Verdict

The call

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.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

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.

ReceptionRating · Positive reviews · Number of ratings

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.

UpkeepUpdate frequency

CRSI Rebar Reference ships an update every 5 weeks, calc318 every 3 months. The most recent releases landed on October 4, 2026 and October 1, 2026 respectively.

Scorecard7 real differences · 3 level
CRSI Rebar Reference versus calc318: the parameters behind the verdict, then further details
ParameterCRSI Rebar Referencecalc318
PriceFreeFree
Rating3.3 (16 ratings)5.0 (1 ratings) — better
Positive reviews33.3% of reviews100.0% of reviews — better
Number of ratings16 — better1
Update frequencyEvery 5 weeks — betterEvery 3 months
AdsNoNo
In-app purchasesYesYes
MonetizationFree — betterSubscription
DevicesiPhone, iPad, iPod — betteriPhone
Requires iOS15.1 — better26.0
Further details — not scored
Size51 MB19 MB
Age rating17+4+
DeveloperConcrete Reinforcing Steel InstituteARTIFICIAL INTELLIGENCE OPTIMIZATION AND SOFTWARE AIOS LLC

Customer experience

CRSI Rebar Reference

All ratings16 ratings
Positive50.0%
Neutral12.5%
Negative37.5%
Written reviews9 reviews
Positive33.3%
Neutral11.1%
Negative55.6%

calc318

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

3 purchases

CRSI Rebar Reference

One-time3
  • CRSI - Rebar Identifier Module$2.99
  • CRSI Development Length ACI$4.99
  • CRSI Development length AASHTO$4.99
2 purchases

calc318

Subscriptions2
  • calc318 Pro Monthly7 Days trial$2.991 Month
  • calc318 Pro Yearly7 Days trial$12.991 Year

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 4, 2026 and calc318 on October 1, 2026.

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