Comparison

Ohmulator vs Keystone Pump TDH Calculator

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Ohmulator

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
Currently charting
Read full description

Makes Ohm's Law simple! Ohmulator is a simple, yet robust, electric circuit calculator that enables you to quickly find the unknown variables of a circuit. Ohmulator allows you to easily adjust unit types on the fly (eg. milli Amps, Amps, kilo Amps), which means no prior conversion! Enter two known variables (from: I = Current, R = Resistance, V = Voltage, P = Power), set preferred units, then Ohmulator will calculate and return the previously unknown values. Also an effective (total) resistance calculator. What two App Store reviewers had to say about Ohmulator: "Great. Does what it says. Very good app. Stylish design." 5 Stars - Jamie1990jamie "Awesome app. It simply works. A must have for the radioamateur or electronic nerd. Nice to have the watt law as well." 5 Stars - Per67 Also available for macOS on the Mac App Store.

About

Keystone Pump TDH Calculator

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
Read full description

Keystone Pumps - Keystone Pump TDH Calculator was created to assist Engineers and Technical Personnel with system calculations required for the sizing of slurry pipe systems and slurry pumps. Our program allows the user to simply enter in basic system parameters and our program will calculate the required head pressure and limiting settling velocity. Our desire is to provide our customers with a dynamic tool that allows for ease of selecting slurry pumps. Features: • Supports iOS10 • Built in Slurry Density Calculation • Limiting Settling Velocity Calculation • Slurry Head & Equivalent Water Head Calculation • Built in Pipe Type and Size Database • Entry and Saving of Customer Pipe Sizes • Built in Pipe Fittings Visual Selection Database • Entry and Saving of Custom Pipe Fittings • NPSHA Calculation • US and Metric Units • Saving of Individual Calculation Results • E-Mailing of Individual Calculation Results

Screenshots

Ohmulator4 screens
Keystone Pump TDH Calculator1 screens

Verdict

The call

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.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

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.

ReceptionRating · Positive reviews · Number of ratings

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.

UpkeepUpdate frequency

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.

Scorecard8 real differences · 3 level
Ohmulator versus Keystone Pump TDH Calculator: the parameters behind the verdict, then further details
ParameterOhmulatorKeystone Pump TDH Calculator
Price$0.99Free — better
Rating4.7 (79 ratings)5.0 (1 ratings) — better
Positive reviews81.1% of reviews100.0% of reviews — better
Number of ratings79 — better1
Update frequencyEvery 2 months — betterEvery 6 months
AdsNoNo
In-app purchasesNoNo
MonetizationFreeFree
Best chart rank#190 — better—
DevicesiPhone, iPad, iPod — betteriPhone
Requires iOS10.0 — better17.6
Further details — not scored
Size5 MB3 MB
Age rating4+4+
DeveloperArmchair EngineeringKeystone Pumps LTD

Customer experience

Ohmulator

All ratings79 ratings
Positive92.4%
Neutral5.1%
Negative2.5%
Written reviews37 reviews
Positive81.1%
Neutral8.1%
Negative10.8%

Keystone Pump TDH Calculator

All ratings1 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews1 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

In-app purchases

None

Ohmulator

No in-app purchases

None

Keystone Pump TDH Calculator

No in-app purchases

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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