Resistor Color Code Reader

Read any resistor in seconds.

Tap the bands as you see them on the component and the value appears instantly, with its tolerance and the range the part is actually guaranteed to fall in. Type a value instead and the app shows you which bands print it.

FOUR, FIVE AND SIX BANDS
A 4-band resistor carries two significant digits and a 5-band carries three, so the same colours mean different things on different parts. Most apps quietly assume one format. This one asks, and switching between them keeps the value you already have.

GOLD AND SILVER ARE MULTIPLIERS TOO
Not just tolerances. Without them every sub-ohm resistor is unreadable, and a surprising number of calculators cannot read one.

THE BENCH TOOLS
Unlock surface-mount decoding for 3-digit, 4-digit, R-notation and EIA-96 markings — including the one genuinely ambiguous case, where the app names both readings instead of guessing. Snap any value to the nearest E6, E12, E24, E48 or E96 preferred value and see how far off it is. Add up a handful of resistors in series and in parallel.

ELECTRONICS TOOLKIT
Eight bench calculators for the parts you actually handle. Try each one free.
• Ohm's law — Voltage, current, resistance and power from any two.
• Voltage divider — Pick two resistors to set an output voltage.
• LED resistor — The series resistor that keeps an LED alive.
• Series and parallel — Total resistance of resistors in series and in parallel.
• Standard values — Snap any value to a part you can buy.
• SMD code — Read the number printed on a surface-mount chip.
• Capacitor code — Decode 104, 473K or 4n7, or find the code for a value.
• Unit converter — Move a value between pico, nano, micro, milli, kilo and mega.

WRITTEN THE WAY YOU WRITE IT
Type 4k7, 4.7k, 4700, 470R or R47 — all of them parse, along with a comma decimal mark and Arabic and Persian numerals.

NO ACCOUNT. NO INTERNET NEEDED. NO TRACKING.
Everything is calculated on your phone. Nothing is uploaded anywhere, and the only thing the app ever asks the internet is whether a newer version exists.

Recent changes:
Read any resistor — colour bands, surface-mount markings, and the standard values in between. Offline, no account, no adverts.