# Ohmulator vs Keystone Pump TDH Calculator

The clearest difference is price: Keystone Pump TDH Calculator at Free against Ohmulator's $0.99. Keystone Pump TDH Calculator also leads on rating (5.0 vs 4.7) and review sentiment (100% vs 81%). Ohmulator's advantage is ratings volume (79 vs 1) and update cadence (every 2 months vs every 6 months). On ads, in-app purchases and monetization model there is nothing between them.

Keystone Pump TDH Calculator is free to download; Ohmulator costs $0.99 up front. Neither carries in-app purchases, so what you see is what you pay.

Keystone Pump TDH Calculator holds the better App Store score, 5.0 against 4.7. That said, the two scores are not equally well evidenced: Ohmulator has 79 ratings behind it against 1, so its average is the more settled of the two. Written reviews point the same way: 81% of Ohmulator's written reviews are positive against 100% of Keystone Pump TDH Calculator's.

Ohmulator ships an update every 2 months, Keystone Pump TDH Calculator every 6 months. The most recent releases landed on October 13, 2026 and October 1, 2026 respectively.

## The numbers

| Metric | Ohmulator | Keystone Pump TDH Calculator |
| --- | --- | --- |
| Price | $0.99 | **Free** |
| Rating | [4.7 (79 ratings)](https://appshunter.io/ios/app/ohmulator/id398901336/reviews) | **[5.0 (1 ratings)](https://appshunter.io/ios/app/keystone-pump-tdh-calculator/id880925443/reviews)** |
| Number of ratings | **79** | 1 |
| Positive reviews | 81.1% of reviews | **100.0% of reviews** |
| In-app purchases | No | No |
| Ads | No | No |
| Update frequency | **Every 2 months** | Every 6 months |
| Monetization | Free | Free |
| Best chart rank | **#190** | — |
| Size | 5 MB | 3 MB |
| Requires iOS | **10.0** | 17.6 |
| Devices | **iPhone, iPad, iPod** | iPhone |
| Age rating | 4+ | 4+ |
| Developer | [Armchair Engineering](https://appshunter.io/developer/398901339) | [Keystone Pumps LTD](https://appshunter.io/developer/435839301) |

## What reviewers say

### Ohmulator

[App page](https://appshunter.io/ios/app/ohmulator/id398901336)

**Currently charting:** #190 Top Paid · Utilities (US App Store)

This electric circuit calculator simplifies Ohm's Law calculations. It allows users to input two known variables (current, resistance, voltage, or power) and automatically computes the unknown values. The app also supports on-the-fly unit adjustments, eliminating the need for manual conversions.

**Highlights:** Ohm's Law calculations, Calculate unknown variables, Adjustable unit types, Total resistance calculator, Supports Voltage, Current, Resistance, Power

**Features:** Vision Pro support

**In-app purchases:** none


### Keystone Pump TDH Calculator

[App page](https://appshunter.io/ios/app/keystone-pump-tdh-calculator/id880925443)

This utility app assists engineers and technical personnel in calculating system parameters for slurry pipe and pump sizing. It computes required head pressure and limiting settling velocity based on user-inputted system data. The tool aims to simplify the selection process for slurry pumps.

**Highlights:** Slurry Density Calculation, Limiting Settling Velocity Calculation, Slurry Head & Equivalent Water Head Calculation, Pipe Type and Size Database, NPSHA Calculation, US and Metric Units, Save Calculation Results

**Features:** macOS Compatibility

**In-app purchases:** none


## Frequently asked questions

### Is Ohmulator free?

Ohmulator costs $0.99, with no in-app purchases.

### Is Keystone Pump TDH Calculator free?

Keystone Pump TDH Calculator is free to download, with no in-app purchases.

### Which has better reviews, Ohmulator or Keystone Pump TDH Calculator?

Keystone Pump TDH Calculator is rated higher. Ohmulator averages 4.7 out of 5 from 79 ratings, while Keystone Pump TDH Calculator averages 5.0 from 1 ratings.

### Do Ohmulator or Keystone Pump TDH Calculator have ads?

Neither Ohmulator nor Keystone Pump TDH Calculator shows ads.

### Which is updated more often, Ohmulator or Keystone Pump TDH Calculator?

Ohmulator ships an update every 2 months, and Keystone Pump TDH Calculator every 6 months. Most recently, Ohmulator was updated on October 13, 2026 and Keystone Pump TDH Calculator on October 1, 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.*