# Acid Plus - The ABG Calculator — Fast, powerful acid-base data

> ABG calculator for healthcare professionals, offering fast and detailed acid-base analysis. (iPhone/iPad app by Free Radical Software.)

- Source: https://appshunter.io/ios/app/acid-plus-the-abg-calculator/id300521236 (this page in markdown: same URL + `.md`)
- Developer: [Free Radical Software](https://appshunter.io/developer/300521249)
- Category: Medical, Health & Fitness
- Price: Free with in-app purchases
- Rating: 4.90/5 from 71 App Store ratings · 34 written reviews indexed
- Age rating: 17+
- Requires: iOS 14.1 · 26 MB
- Languages: American English
- Released: 2008-12-22
- Data updated: 2026-08-27
- Monetization: free with in-app purchases
- User reviews in markdown: https://appshunter.io/ios/app/acid-plus-the-abg-calculator/id300521236/reviews.md

## What is Acid Plus?

Designed, programmed, and used by two internal medicine docs, Acid Plus is an essential tool for healthcare professionals who need quick, detailed, and easy-to-interpret acid-base results from ABGs and metabolic panels.

Ideal for MDs, PAs, NPs, RNs, RTs, EMTs, and med students, everything you need for acid-base calculations is put right in the palm of your hand. No more clunky ABG websites or guesswork.

With an intuitive design and easy-to-read display, Acid Plus makes it a breeze to answer even the most complex acid-base problems in seconds.  Just turn the device to landscape view to get a colorful graph with an arrow highlighting the disorder.

*** What Others Say **************

• "This is certainly the best ABG calculator that we have seen so far on the iPhone and iPod Touch."
   - Firas Salim, www.pda4peds.com

• "If you are practicing medicine and own an iPhone, you need to have it."
   - Igor Kovic, MD, www.ivor-kovic.com

• "Interpreting the ABG and electrolytes to understand the acid-base status in my patients just turned from a chore into something immensely enjoyable. I cannot help smiling whenever I start this application."

• "This program is awesome! You have no idea how much this helps. Thank you so much."

********************************

Features:
• Fast, accurate input using the dial 
• Primary calculations including partial and complete compensations using anion gap with delta delta
• International support for kPa
• Ability to discern complex acid/base problems with secondary disorders
• See the anion gap and delta delta displayed on-screen with metabolic acidoses
• Detailed views listing common causes of the primary acid-base disorder
• On-the-fly derivation of anion gap, delta-delta, and base excess
• Rotating your device right or left to landscape view reveals a colorful interactive acid-base graph
• Interactive graph helps visualize acid-base disorders quickly and powerfully
• Set your own institution's anion gap easily for personalized results
• Save and recall your most recent ABG for quick review
• Works on iPhone and iPad



If you like the program please rate it. If you have any concerns or find any bugs please contact us at support@freeradicalsoft.com

DISCLAIMER: Please consider that the results provided by this program are intended to supplement but not substitute for the expertise and clinical judgment of a healthcare professional. The results and accompanying educational material are provided as is, and Free Radical does not warrant that they are accurate or up to date, although that is certainly our goal.

## Key features

- Fast ABG and metabolic panel calculations
- Detailed interpretation of acid-base disorders
- Interactive color graph visualization
- Anion gap and delta delta display
- International unit support (kPa)
- Customizable anion gap settings
- Save and recall recent ABGs

## Pricing and in-app purchases

Base price: Free.

**Subscriptions**

| Subscription | Price | Period |
| --- | --- | --- |
| Quarterly Subscription | $1.99 | per 3 months |
| Annual Subscription | $5.99 | per year |
| Monthly Subscription | $0.99 | per month |

**One-time purchases**

| Purchase | Price | Type |
| --- | --- | --- |
| Acid Plus Lifetime Upgrade | $17.99 | one-time |


## Recent user reviews (10 of 34)

All indexed reviews: https://appshunter.io/ios/app/acid-plus-the-abg-calculator/id300521236/reviews.md

### 5/5 — Love this ABG app

*2021-07-04*

The perfect app for the wards.  The picker for choosing values is great.

### 5/5 — So great to see this app return!

*2021-07-04*

I’ve been missing this for a while but all the extra details available and being able to set the graph manually are really useful. Great update, thanks!

### 5/5 — So useful

*2021-07-02*

Not only is it easy to use but there’s just so much detailed info available. Really helpful to be able to see how all the results are derived.

### 5/5 — Great app

*2018-10-22*

Please update for new IOS versions!!!!!

**Developer response:** Acid Plus version 3 is now available and should work with your iPhone or iPad. To welcome you back, please email us at support@freeradicalsoft.com and we'll send you a code for year-long free subscription.

### 5/5 — Good

*2018-10-09*

Update ur software as I love this program
Hurry up

### 1/5 — Needs update

*2018-04-17*

It was great but can’t use it anymore

**Developer response:** Glad you liked using Acid Plus, but sorry it was unavailable to you. We're back now with the new and improved version 3, which should run your great on your iPhone or iPad. If you like the new version, please consider updating your review. And since we made you wait, please email us at support@freeradicalsoft.com and we'll send you a code for year-long free subscription.

### 1/5 — I want my money back!!!

*2018-02-11*

It doesn't work for IOS 10!!!
Shame on you!!
Please fix this bug

**Developer response:** Glad you liked using Acid Plus, but sorry it was unavailable to you. We're back now with the new and improved version 3, which should run your great on your iPhone or iPad. If you like the new version, please consider updating your review. And since we made you wait, please email us at support@freeradicalsoft.com and we'll send you a code for year-long free subscription.

### 1/5 — Doesn’t work

*2017-11-14*

Doesn’t work with new iOS update

**Developer response:** Glad you liked using Acid Plus, but we're sorry it was unavailable to you. We're back now with the new and improved version 3, which should run your great on your iPhone or iPad. If you like the new version, please consider updating your review. And since we made you wait, please email us at support@freeradicalsoft.com and we'll send you a code for year-long free subscription.

### 2/5 — when updated to iOS11？

*2017-11-13*

can't wait

**Developer response:** Glad you liked using Acid Plus, but sorry it was unavailable to you. We're back now with the new and improved version 3, which should run your great on your iPhone or iPad. If you like the new version, please consider updating your review. And since we made you wait, please email us at support@freeradicalsoft.com and we'll send you a code for year-long free subscription.

### 3/5 — Need the update

*2017-11-06*

It was a 5 star but not able to use with new IOS so rating is zero. Three is until update so I can use again and bring rating back to five. Please update

**Developer response:** We're glad you liked using Acid Plus, but we're sorry it was unavailable to you. We're back now with the new and improved version 3, which should run your great on your iPhone or iPad. If you like the new version, please consider updating your review. And since we made you wait, please email us at support@freeradicalsoft.com and we'll send you a code for year-long free subscription.

## Frequently asked questions about Acid Plus

### What does Acid Plus do?

Acid Plus is a mobile application designed for healthcare professionals to quickly and accurately calculate and interpret acid-base results from Arterial Blood Gases (ABGs) and metabolic panels. It helps in understanding complex acid-base disorders and visualizing them with an interactive graph.

### What are the key features of Acid Plus?

Key features include fast and accurate input using a dial, primary calculations with compensations and anion gap, international support for kPa, the ability to discern complex disorders, on-screen display of anion gap and delta-delta, detailed views of common causes, and an interactive graph that visualizes disorders in landscape view.

### How much does Acid Plus cost?

The application is available for free with in-app purchases. Specific features or advanced functionalities may require a purchase within the app.

### What devices is Acid Plus compatible with?

Acid Plus is designed to work on both iPhone and iPad devices, offering a convenient tool for healthcare professionals on the go.

### Who would benefit from using Acid Plus?

This app is ideal for medical doctors (MDs), Physician Assistants (PAs), Nurse Practitioners (NPs), Registered Nurses (RNs), Respiratory Therapists (RTs), Emergency Medical Technicians (EMTs), and medical students who frequently deal with ABG and metabolic panel analysis in their clinical practice.

## Version history (last 5 releases)

### 3.3.1 — 2022-06-14

Thank you for using Acid Plus!
- fixed picker for smaller screen sizes

We continue to make other minor bug improvements

### 3.3.0 — 2022-04-24

Thank you for using Acid Plus!
- added ability to choose light or dark mode within the app
- improved appearance of the picker

We continue to make other minor bug improvements

Please feel to reach out with feature requests or bug reports.

### 3.2.0 — 2022-03-23

Thank you for using Acid Plus 

We continue to make minor bug improvements to get the Lifetime upgrade available to our valued users
Please feel to reach out with feature requests or bug reports.

### 3.1.1 — 2022-03-22

Thank you for using Acid Plus!

This version includes minor bug fixes

### 3.1.0 — 2022-03-21

- Tired of subscriptions? After testing Acid Plus for a month for free, you can now *unlock Acid Plus for life* with a one-time purchase.
- Bug fixes and improvements

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## More apps by Free Radical Software

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All apps by Free Radical Software: https://appshunter.io/developer/300521249

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*Data collected daily from the US App Store and indexed by [AppsHunter](https://appshunter.io/). User reviews are verbatim App Store reviews. Ratings, prices and chart positions refresh continuously; this snapshot is from 2026-08-27.*