Offline electronics toolkit

Read resistor colors or turn a value into bands.

Choose 3, 4, 5, or 6 bands, tap each color, and get the value, tolerance, range, and temperature coefficient instantly.

Open Calculator View Color Chart

4.7 kΩ ±5% Yellow • Violet • Red • Gold

Main tool

Band-to-value calculator

Resistance1 kΩ Brown • Black • Red • Gold

Tolerance±5%950 Ω – 1.05 kΩ

Temperature coefficient—Available on 6-band resistors

Band explanation10 × 1002 significant digits and multiplier

Reverse lookup

Value-to-color calculator

Preferred values

Nearest E-series resistor

Circuit calculator

Series and parallel

Resistor values separated by commas

Unit

Electrical calculator

Ohm’s law and power

Enter any two values. Leave the other two blank.

Voltage (V) Current (A) Resistance (Ω) Power (W)

Reference

Resistor color-code chart

Color	Digit	Multiplier	Tolerance	Tempco

How to read the bands

Start from the end where the first band is closest to the resistor edge. The tolerance band is commonly separated by a wider gap and is often gold or silver.

3 and 4 bands

Two significant digits, one multiplier, and—on a 4-band part—a tolerance band. A 3-band resistor normally implies ±20% tolerance.

5 and 6 bands

Three significant digits provide finer values. The sixth band adds temperature coefficient in parts per million per degree Celsius.

Power rating

Color bands do not normally identify wattage. Physical size and the manufacturer’s datasheet determine the safe power rating.

Learning resources

Trusted resistor references

DigiKey color-code calculator4-, 5-, and 6-band reference and component search. TE Connectivity color-code guideOverview of IEC-style resistor markings. EE Power resistor guideConstruction, standards, applications, and selection guidance. DigiKey series/parallel calculatorIndependent reference for resistor networks.

Semiconductor reference

Find transistor and MOSFET specs—and compare possible substitutes.

Search common BJTs and MOSFETs by part number, polarity, package, voltage, current, gain, on-resistance, and pinout. The substitution checker highlights electrical and mechanical differences before you install a replacement.

Open Device Library Compare Parts

BJT
↔
MOSFET

Parts LibraryOffline searchable reference

Searchable database

Transistor & MOSFET library

Part number or keyword Device type Package Minimum voltage

Interchange assistant

Compare a device with a possible substitute

Original device Possible replacement

BJT gain is not fixed

hFE is a range that changes with collector current, temperature, and device grade. Design around the guaranteed minimum—not a single meter reading.

MOSFET gate voltage matters

A low threshold voltage does not automatically mean low resistance at 3.3 V or 5 V. Look for an RDS(on) specification at your actual gate-drive voltage.

Pinouts can differ

Two electrically similar parts can use different lead orders. Always compare the exact manufacturer datasheets and package drawings.

Heat sinking matters

Current ratings assume specified temperature and thermal conditions. Check power dissipation, safe operating area, mounting, and heatsink requirements.

Important substitution rule

This tool suggests candidates and identifies differences; it does not certify a drop-in replacement. Verify voltage, current, power, gain or gate drive, switching speed, package, pinout, polarity, safe operating area, and the exact manufacturer datasheet before installation.