Resistor Calc Toolbox
LED & Resistor Calculators
$2.99
Quickly calculate LED resistor values, decode 4-band resistor color codes, or convert resistance values back into color bands.
Resistor Calc Toolbox is a simple, easy-to-use electronics utility for working with LEDs and 4-band resistors.
Three calculators put commonly needed resistor information in one convenient app.
LED Resistor Calculator
Enter the supply voltage, LED forward voltage, and LED current to calculate the required resistance and minimum resistor power rating.
Color Bands → Ohms
Select the four resistor color bands to calculate the resistance value, tolerance, and tolerance range.
Ohms → Color Bands
Enter a resistance value and tolerance to find the corresponding 4-band resistor colors.
Features
• Three resistor tools in one app
• LED resistance and power calculations
• 4-band resistor color code decoding
• Resistance-to-color-band conversion
• Resistance tolerance range
• Support for common resistor multiplier and tolerance colors
• Clean, straightforward interface
• Works on iPhone and iPad
Whether you're working at the electronics bench, experimenting with LED circuits, or simply need a quick resistor reference, Resistor Calc Toolbox keeps the calculations close at hand.
Important: Calculations are based on the values you enter and are provided as a design aid. Verify component values, ratings, tolerances, and suitability for your specific circuit before use.
I particularly like including our disclaimer at the bottom of the App Store description. It doesn't interfere with the sales pitch, but it's visible before purchase.
Ratings & Reviews
- This app hasn’t received enough ratings or reviews to display an overview.
The developer, Kevin Kuromi, indicated that the app’s privacy practices may include handling of data as described below. For more information, see the developer’s privacy policy .
Data Not Collected
The developer does not collect any data from this app.
Accessibility
The developer has not yet indicated which accessibility features this app supports. Learn More
Information
- Seller
- Kevin Kuromi
- Size
- 5.4 MB
- Category
- Utilities
- Compatibility
Requires iOS 17.6 or later.
- iPhone
Requires iOS 17.6 or later. - iPad
Requires iPadOS 17.6 or later.
- iPhone
- Languages
- English
- Age Rating
4+
- 4+
- Copyright
- © 2026 Kevin Kuromi
