Report updated May 17, 2026
Four To Twenty: mA/V Converter
For industrial technicians and engineers requiring quick field calculations for 4-20mA signal loops.
Four To Twenty: mA/V Converter is a well-regarded utilities app that is a paid app. With a 4.5/5 rating from 10 reviews, it maintains solid user satisfaction. Users particularly value the application provides a straightforward and accessible experience for users performing basic mathematical calculations.
What is Four To Twenty: mA/V Converter?
Four To Twenty is a specialized utility calculator for industrial 4-20mA signal loop conversions on iOS.
Technicians hire this tool for rapid, field-ready signal scaling that avoids the overhead of complex, general-purpose scientific calculators.
Current Momentum
v2.0
- Added support for negative numbers.
- Fixed comma decimal calculation errors.
- Added 8 visual themes.
Active Nemesis
Engineers Toolbox
By Charles Crawford
Other Rivals
7-Day Rank Pulse 🇺🇸
UtilitiesRating Pulse 🇺🇸
Recent User Mood
What makes this app unique?
What Does It Look Like?
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What Are The Key Features?
Calculates process signal values from 4-20mA electrical inputs
Allows manual entry of signal ranges beyond presets
Provides 8 distinct visual themes for the interface
How much does it cost?
- Single purchase at $0.99
Paid model anchored at $0.99, capturing revenue through a one-time transaction for specialized industrial utility.
Who Built It?
Jon Giambattista
Providing specialized clinical calculators and utility tools for medical professionals and technical users. Bridging the gap between complex data and actionable clinical decision-making.
Portfolio
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What do users think recently?
Low confidence · 2 reviews analyzed
How did the latest release land?
What is the recent mood?
Recent user voice shows a excited sentiment. Users appreciate the application provides a straightforward and accessible experience for users performing basic mathematical calculations.
Limited review volume (2 reviews). Sentiment analysis will deepen as more data lands.
View the full user-sentiment analysis
Mood gauge, ratings & review-volume history, every praise / complaint / request, and sentiment over time.
What is the competitive landscape for Four To Twenty: mA/V Converter?
How's The Utilities Market?
How does it evolve in the Utilities market?
The app maintains a niche presence in the Utilities category, ranking #77 Paid in the US. The $0.99 price point creates a barrier against free, comprehensive engineering suites that dominate the category.
Rank progression
14 active rankings tracked — 30-day window
Which niche is Four To Twenty: mA/V Converter in?
to convert electrical signals to process values
Explore the full Engineering Calculations Converters niche
Every app in this space — 1 tracked, the niche's live rankings, and Marlvel's editorial take on the job-to-be-done.
The rivals identified
Nemeses(1)
This app serves the same professional engineering audience by bundling signal conversion tools within a broader technical reference suite.
Differentiators
- Aggregates multiple engineering disciplines into one utility rather than focusing on a single signal conversion task.
- Provides a comprehensive reference library that creates higher daily utility for engineers compared to a single-purpose calculator.
Same space(3)
A general-purpose utility that competes for the same screen real estate by offering a more polished, modern interface.
Differentiators
- Focuses on aesthetic design and user experience to capture casual users who find specialized engineering apps too intimidating.
- Leverages a massive user base to drive visibility in the Utilities category, overshadowing niche-specific tools.
A high-end calculator that serves as a premium alternative for users who need custom conversion logic and advanced scientific functions.
Differentiators
- Provides deep customization for user-defined functions that allows for complex signal scaling beyond simple 4-20mA presets.
- Features a highly refined, professional-grade UI that appeals to power users who demand precision and reliability.
While broader in scope, it captures the same professional electrical engineering audience through a massive library of specialized calculators.
Differentiators
- Offers a vast ecosystem of electrical formulas that makes the app a permanent fixture in a technician's toolkit.
- Maintains high-frequency update cycles that ensure compatibility with the latest iOS standards and engineering requirements.
New entrants(1)
Demonstrates high velocity with four releases in the last six months, signaling active development and feature expansion.
Differentiators
- Uses real-time hardware monitoring to provide actionable data, moving beyond static calculations into dynamic system diagnostics.
- Aggressive update cadence allows for rapid integration of user feedback and new device-specific hardware support.
Compare Four To Twenty: mA/V Converter against every rival
All rivals in one side-by-side table — identity, store metrics, ratings & sentiment, and strategic intel — plus a head-to-head page for each.
The outtake for Four To Twenty: mA/V Converter
Strengths to defend, gaps to attack
Core Strengths
- Simple interface reduces cognitive load for field technicians
- 8 visual themes provide aesthetic differentiation in a utilitarian category
Critical Frictions
- $0.99 price point creates a barrier against free, comprehensive engineering suites
- Lack of formula transparency limits professional trust
Growth Levers
- Integration of percentage-based range mapping would capture users needing to interpret partial signal values
Market Threats
- Multi-tool engineering suites bundle conversion logic, rendering single-purpose calculators redundant
What are the next best moves?
Expose underlying math formulas because users request logic transparency → increase professional utility
Formula transparency is the #1 requested feature in user sentiment data.
Trade-off: Push the theme customization update to Q3 — formula logic has higher impact on professional retention.
Pivot to a freemium model because $0.99 entry barrier limits new user acquisition → increase install velocity
Free engineering suites are the primary competitive threat to the current paid model.
Trade-off: Pause the one-time purchase revenue stream — freemium conversion volume will offset the initial price loss.
A counter-intuitive read
The app's simplicity is its greatest weakness, as it prevents it from becoming the 'all-in-one' reference tool that engineers actually keep in their daily toolkit.
Feature Gaps vs Competitors
- Comprehensive engineering reference library (available in Engineers Toolbox but absent here)
- Advanced scientific functions (available in PCalc but absent here)
Key Takeaways
The app succeeds as a simple, dedicated tool, but its paid model is vulnerable to free, feature-rich engineering suites, so the PM should pivot to a freemium model and add formula transparency to secure professional adoption.
Where Is It Heading?
Stable
The industrial utility market is consolidating around multi-tool suites that offer higher daily value than single-purpose calculators. This app remains stable but exposed, so the PM must add professional-grade features like formula transparency to prevent churn to free competitors.
Recent updates added support for negative numbers, showing active maintenance of the core calculation engine.
The $0.99 price point faces increasing pressure from free, comprehensive engineering suites, which limits the app's growth potential.