OhmsLab vs Resistor Code Calculator Pro

The everyday electronics bench in your pocket. Solve Ohm's law, read resistor color codes, and size LED resistors in seconds, all on your iPhone. WHAT IT DOES - Ohm's law and power: enter any two of voltage, current, resistance or power and get the other two - Resistor color decoder: 4, 5 and 6 band, with tolerance and temperature coefficient, drawn on a real resistor - Find the colors for a value: enter a resistance and see the bands - LED series resistor: from supply, forward voltage and current, with the nearest standard value and a power rating - Series and parallel: combine any number of resistors, both totals at once - Voltage divider: output voltage, current and power, plus a helper to size R2 for a target output - Save any calculation to your bench and reopen it live - Bench reference: the full color code table, SI prefixes and the Ohm's law relationships - Copy any result, clean dark bench interface PRIVATE BY DESIGN Everything you enter stays on your iPhone. No account, no cloud, no tracking. FREE AND LIFETIME Free includes the Ohm's law and power solver and the full resistor color decoder, with unlimited saved calculations. The one time Lifetime unlock ($4.99 USD, pay once, no subscription) adds the LED resistor, voltage divider, and series and parallel tools, plus PDF and CSV bench sheet export. Built for makers, students, repair techs, and anyone who keeps a soldering iron warm. A planning aid for hobby and bench work. Check part datasheets and ratings before you build.

Resistor Calculator is a practical offline toolbox for electronics students, makers, repair technicians, and engineers who work with resistors and common circuit calculations. Decode resistor color bands, convert resistance values into color bands, read SMD resistor markings, browse E-Series values, and solve everyday resistor-related circuit problems in one focused app. RESISTOR TOOLS • Decode 3, 4, 5, and 6-band resistors • Convert resistance values into color bands • Support engineering notation such as 4.7k, 4k7, 2M2, and 0R22 • Calculate tolerance, minimum, and maximum resistance • Show temperature coefficient for 6-band resistors • Reverse resistor reading direction • Copy, share, save, and reset results SMD RESISTOR CODES • Decode 3-digit and 4-digit SMD codes • Support R, K, and M notation • Support EIA-96 markings • Handle zero-ohm resistors • Convert resistance values back into suitable SMD codes • Explain decoded values clearly E-SERIES VALUES • Browse E6, E12, E24, E48, E96, and E192 values • Find the nearest standard resistor values • Compare error and tolerance ranges • Open selected values directly in resistor tools CIRCUIT CALCULATORS • Series and parallel resistance • Ohm’s Law • Voltage divider • LED current-limiting resistor • Target resistance combinations • Wheatstone bridge • Op-amp gain • Star / Delta conversion • Wire resistance • Voltage drop • Pull-up / Pull-down resistor • RC time constant LIBRARY WORKFLOW • Save calculation history • Add results to Favorites • Organize values and calculations into Projects • Export project data as CSV, JSON, or plain text • Review saved calculations later BUILT FOR DAILY ELECTRONICS WORK Resistor Calculator is designed to be fast, clear, and focused. Results update immediately as you enter values, and formulas are available when you need to understand how a calculation was made. All core calculations run on your device and the app works without an account or internet connection.