# Duty vs Voltage Drop Calculators

The clearest difference is price: Duty at Free against Voltage Drop Calculators's $3.99. Duty also leads on update cadence (every 3 days vs every 7 months). Voltage Drop Calculators's advantage is in-app purchases (none vs 1) and iOS requirement (15.6 vs 17.6). On ads and device support there is nothing between them.

Duty is free to download; Voltage Drop Calculators costs $3.99 up front. Duty sells 1 in-app purchase, starting at $1.99 per year. Voltage Drop Calculators asks for nothing beyond the download.

Duty ships an update every 3 days, Voltage Drop Calculators every 7 months. Both last shipped on November 3, 2026.

## The numbers

| Metric | Duty | Voltage Drop Calculators |
| --- | --- | --- |
| Price | **Free** | $3.99 |
| Rating | — | **[4.0 (4 ratings)](https://appshunter.io/ios/app/voltage-drop-calculators/id6464050324/reviews)** |
| Number of ratings | — | **4** |
| In-app purchases | Yes | **No** |
| Ads | No | No |
| Update frequency | **Every 3 days** | Every 7 months |
| Monetization | — | Paid |
| Size | 44 MB | 67 MB |
| Requires iOS | 17.6 | **15.6** |
| Devices | iPhone, iPad | **iPhone, iPad, iPod** |
| Age rating | 4+ | 4+ |
| Developer | [Martin Handl](https://appshunter.io/developer/1202513077) | [Kantaben Gorasiya](https://appshunter.io/developer/1640260396) |

## What reviewers say

### Duty

[App page](https://appshunter.io/ios/app/duty-rest/id6450999374)

**Features:** macOS Compatibility, Family Sharing

**In-app purchases (1)**

| Purchase | Price | Billing |
| --- | --- | --- |
| Unlimited access | $1.99 | per year |


### Voltage Drop Calculators

[App page](https://appshunter.io/ios/app/voltage-drop-calculators/id6464050324)

This tool helps electrical professionals and students perform quick and accurate voltage drop calculations. It features a user-friendly interface, a material database, and the ability to save circuit details for efficient system design and compliance.

**Highlights:** Fast voltage drop calculations, Built-in material database, Custom material support, Save circuit details, Unit conversion, Recommended wire size guidance

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

**In-app purchases:** none


## Frequently asked questions

### Is Duty free?

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

### Is Voltage Drop Calculators free?

Voltage Drop Calculators costs $3.99, with no in-app purchases.

### Do Duty or Voltage Drop Calculators have ads?

Neither Duty nor Voltage Drop Calculators shows ads.

### Which is updated more often, Duty or Voltage Drop Calculators?

Duty ships an update every 3 days, and Voltage Drop Calculators every 7 months. Most recently, Duty was updated on November 3, 2026 and Voltage Drop Calculators on November 3, 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.*