Resistor Color Code Calculator

How to read a 4-band resistor color code

A resistor's color bands encode its resistance value directly on the component, since the actual number is too small to print legibly. On the most common 4-band resistor, the first two bands are significant digits, the third band is a power-of-ten multiplier, and the fourth band states the manufacturing tolerance. Choose a color for each band above and click Calculate to decode the resistance, its tolerance, and the minimum and maximum values the part is guaranteed to fall within.

The standard color code

Each color from black through white stands for a digit 0-9 in the two digit bands, and doubles as a power of ten in the multiplier band: black=0, brown=1, red=2, orange=3, yellow=4, green=5, blue=6, violet=7, gray=8, white=9. Two extra colors appear only on the multiplier band, for resistors below 10 ohms: gold means x0.1 and silver means x0.01. The tolerance band uses its own small set of colors: brown=+/-1%, red=+/-2%, gold=+/-5%, silver=+/-10%, and no fourth band at all traditionally means +/-20%.

The formula

Resistance = (10 x first digit + second digit) x multiplier. For example, brown-black-red-gold reads as 1, 0, x100, +/-5%, giving (10x1+0)x100 = 1,000 ohms, or 1 kilo-ohm, guaranteed to measure within +/-5% of that value — between 950 and 1,050 ohms.

Interpreting the results

The Resistance card shows the nominal value the manufacturer targeted. Tolerance shows how far a real part is allowed to drift from that nominal value. Minimum and Maximum give the guaranteed range — any resistor with this color code should read somewhere between those two figures on a multimeter, even though the value implied by the bands is a single nominal number.

Frequently Asked Questions

How does the 4-band resistor color code work?

The first two bands are significant digits (0-9), the third band is a power-of-ten multiplier, and the fourth band is the tolerance. The resistance equals (10 x first digit + second digit) x multiplier, so brown-black-red-gold decodes to (10x1+0)x100 = 1,000 ohms with a plus-or-minus 5% tolerance.

What do gold and silver mean in the multiplier band?

On the third band, most colors multiply the two-digit number by a power of ten, from black (x1) up to white (x1,000,000,000). Gold and silver are exceptions reserved for sub-10-ohm resistors: gold means x0.1 and silver means x0.01, so red-red-gold reads as 22 x 0.1 = 2.2 ohms.

What does the tolerance band tell you?

Tolerance is the maximum percentage a real resistor is allowed to deviate from its printed nominal value. A 1 kilo-ohm resistor with a gold (plus-or-minus 5%) tolerance band will measure somewhere between 950 and 1,050 ohms; tighter tolerances like brown (1%) or red (2%) indicate a more precisely manufactured part, usually at a higher price.

How is a 5-band or 6-band resistor different from a 4-band one?

5-band and 6-band resistors add a third significant-digit band for higher precision, so three digits are read before the multiplier instead of two, and 6-band parts add a temperature-coefficient band after the tolerance band. This calculator covers the standard 4-band code; a 5-band or 6-band resistor is not modeled here.

Common Tip Percentages

Service	Typical Tip Range	Notes
Restaurant (sit-down)	15–20%	20%+ for exceptional service
Food delivery	10–20%	Consider extra for long distances
Taxi / rideshare	10–20%	More for assistance with luggage
Hotel housekeeping	$2–5/night	Leave daily, not just at checkout
Barber / hair salon	15–20%	On pre-discount total
Pizza delivery	10–15% or $3–5 minimum	Higher in bad weather

General Household Budget Ratios (50/30/20 Rule)

Category	% of Net Income	Examples
Needs	50%	Rent, groceries, utilities, insurance
Wants	30%	Dining out, entertainment, hobbies
Savings / Debt	20%	Emergency fund, retirement, extra payments

Common Measurement Conversions for Everyday Use

Quantity	US / Imperial	Metric Equivalent
1 cup	8 fl oz	237 mL
1 pint	16 fl oz	473 mL
1 quart	32 fl oz	946 mL
1 gallon	128 fl oz	3.785 L
1 lb	16 oz	453.6 g
1 ft	12 in	30.48 cm