# Resistor Tools vs Operational Amplifiers Guide

The clearest difference is in-app purchases: Operational Amplifiers Guide at none against Resistor Tools's 1. Resistor Tools's advantage is ads (none vs shown) and iOS requirement (12.0 vs 16.0). On price, update cadence and device support there is nothing between them.

Both are free to download. Resistor Tools sells 1 one-off in-app purchase. Operational Amplifiers Guide asks for nothing beyond the download.

Both ship on a similar rhythm, roughly every 2 months. The most recent releases landed on September 26, 2026 and September 19, 2026 respectively.

## The numbers

| Metric | Resistor Tools | Operational Amplifiers Guide |
| --- | --- | --- |
| Price | Free | Free |
| Rating | **[5.0 (10 ratings)](https://appshunter.io/ios/app/resistor-tools/id826045228/reviews)** | — |
| Number of ratings | **10** | — |
| Positive reviews | 75.0% of reviews | — |
| In-app purchases | Yes | **No** |
| Ads | **No** | Yes |
| Update frequency | Every 2 months | Every 2 months |
| Monetization | Free with in-app purchases | — |
| Size | 4 MB | 17 MB |
| Requires iOS | **12.0** | 16.0 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Siu Yuen Ho](https://appshunter.io/developer/814088527) | [ALG Software Lab](https://appshunter.io/developer/1650561236) |

## What reviewers say

### Resistor Tools

[App page](https://appshunter.io/ios/app/resistor-tools/id826045228)

This utility app provides a suite of tools for calculating and determining resistor values. It assists hobbyists and engineers with series, parallel, and voltage divider calculations, as well as inverting amplifier gain.

**Highlights:** Series and parallel resistor calculation, Resistor combination finder, Voltage divider ratio and value calculation, Inverting amplifier gain calculation, Save combinations to CSV

**Features:** Vision Pro support

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Unlock pro feature | $0.99 | one-time |


### Operational Amplifiers Guide

[App page](https://appshunter.io/ios/app/operational-amplifiers-guide/id6467499897)

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

**In-app purchases:** none


## Frequently asked questions

### Is Resistor Tools free?

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

### Is Operational Amplifiers Guide free?

Operational Amplifiers Guide is free to download, with no in-app purchases.

### Do Resistor Tools or Operational Amplifiers Guide have ads?

Operational Amplifiers Guide shows ads; Resistor Tools does not.

### Which is updated more often, Resistor Tools or Operational Amplifiers Guide?

Resistor Tools ships an update every 2 months, and Operational Amplifiers Guide every 2 months. Most recently, Resistor Tools was updated on September 26, 2026 and Operational Amplifiers Guide on September 19, 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.*