# Resistor calc vs 九天八字

The clearest difference is price: 九天八字 at Free against Resistor calc's $1.99. 九天八字 also leads on update cadence (weekly vs every 2 months). Resistor calc's advantage is in-app purchases (none vs 3) and iOS requirement (13.0 vs 26.2). On ads and device support there is nothing between them.

九天八字 is free to download; Resistor calc costs $1.99 up front. 九天八字 sells 3 one-off in-app purchases. Resistor calc asks for nothing beyond the download.

Resistor calc ships an update every 2 months, 九天八字 weekly. The most recent releases landed on November 12, 2026 and October 31, 2026 respectively.

## The numbers

| Metric | Resistor calc | 九天八字 |
| --- | --- | --- |
| Price | $1.99 | **Free** |
| In-app purchases | **No** | Yes |
| Ads | No | No |
| Update frequency | Every 2 months | **Weekly** |
| Size | 17 MB | 10 MB |
| Requires iOS | **13.0** | 26.2 |
| Devices | **iPhone, iPad, iPod** | iPhone, iPad |
| Age rating | 4+ | 4+ |
| Developer | [Anas Abubakar](https://appshunter.io/developer/1581534101) | [美薇 殷](https://appshunter.io/developer/1884920025) |

## What reviewers say

### Resistor calc

[App page](https://appshunter.io/ios/app/resistor-calc-electronics/id6477826973)

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

**In-app purchases:** none


### 九天八字

[App page](https://appshunter.io/ios/app/id6761317780)

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

**In-app purchases (3)**

| Purchase | Price | Billing |
| --- | --- | --- |
| 月度会员 | $3.99 | one-time |
| 年度会员 | $29.99 | one-time |
| 8年会员 | $99.99 | one-time |


## Frequently asked questions

### Is Resistor calc free?

Resistor calc costs $1.99, with no in-app purchases.

### Is 九天八字 free?

九天八字 is free to download, with in-app purchases available.

### Do Resistor calc or 九天八字 have ads?

Neither Resistor calc nor 九天八字 shows ads.

### Which is updated more often, Resistor calc or 九天八字?

Resistor calc ships an update every 2 months, and 九天八字 weekly. Most recently, Resistor calc was updated on November 12, 2026 and 九天八字 on October 31, 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.*