Resistor color code calculator

Resistor Color Code Calculator: decode any resistor in seconds from its color bands or SMD code, or go the other way and find the bands for any resistor value.

A complete electronics bench tool for students, hobbyists, repair techs and engineers. This resistor calculator works fully offline, has no ads, and nothing you do leaves your phone.

★ RESISTOR COLOR CODE CALCULATOR

- Read 3, 4, 5 and 6-band resistors

- Tap a color and the resistor value, tolerance and real-world range update instantly

- Two layouts: Classic, with the whole color grid on one screen, and Modern, with a large result card. Switch from the title bar; your choice is remembered

- See the calculation written out (47×10² ±5%), the tolerance range, the E-series the value belongs to, and the temperature coefficient on 6-band parts

- A realistic resistor drawing shows the bands exactly where they sit on the part

- Copy or share any reading

★ REVERSE LOOKUP: RESISTOR VALUE TO COLOR BANDS

- Type a resistance in ohms and a tolerance, get the band sequence that encodes it

- Tells you whether it is an exact preferred value or the nearest one

- Works for 3, 4, 5 and 6-band layouts

- A quick ohm calculator for picking the right part from your drawer

★ SMD RESISTOR CODE CALCULATOR

- 3-digit SMD codes (472 = 4.7 kΩ)

- 4-digit EIA codes (4702 = 47 kΩ)

- EIA-96 codes with the letter multiplier (01C = 10.0 kΩ, E-96, 1%)

- R notation for decimals (4R7 = 4.7 Ω)

- Underlined codes read in milliohms

- A purpose-built keypad, so you are not fighting a phone keyboard

★ COLOR BAND CHART AND REFERENCE TABLES

- The complete resistor color code chart: digit, multiplier and tolerance for all twelve colors

- Preferred-value series at a glance

- Always available, always offline

★ QUIZ: LEARN THE RESISTOR COLOR CODE

- Six topics: band colors, reading a resistor, finding the bands, tolerance and range, SMD codes and preferred values

- Six question types: multiple choice, true or false, type the answer, read the part, put in order and match the pairs

- Four difficulties: Easy, Medium, Hard, and Adaptive, which follows how you are doing

- An optional per-question timer

- Every answer comes with an explanation of the rule behind it

- Points, levels, day streaks, accuracy and eight badges to unlock

- A daily challenge: five questions, the same for everyone that day

- Spaced repetition: questions you get wrong come back at the right moment

- Your best weeks, ranked

- Sound effects you can switch off

- Great for electronics students preparing for labs and exams

★ PRIVATE, OFFLINE AND AD-FREE

- Works with no internet connection at all

- No ads, anywhere

- No account and no sign-in

- No analytics, no tracking, no crash reporting

- Nothing you calculate or answer ever leaves your device

- Light and dark themes

- Full screen-reader support, with every color named as well as shown

A free resistor color code calculator with no ads and no in-app purchases.