Resistor Band to Resistance Calculator

Resistance Formula:

\[ R = (band1 \times 10 + band2) \times 10^{band3} \]

First Band (Digit):

Second Band (Digit):

Third Band (Multiplier):

Resistance (Ω):

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1. What is a Resistor Band to Resistance Calculator?

Definition: This calculator determines the resistance value of a resistor based on its color bands.

Purpose: It helps electronics engineers, technicians, and hobbyists quickly decode resistor values without memorizing the color code.

2. How Does the Calculator Work?

The calculator uses the formula:

\[ R = (band1 \times 10 + band2) \times 10^{band3} \]

Where:

\( R \) — Resistance in ohms (Ω)
\( band1 \) — First significant digit (first color band)
\( band2 \) — Second significant digit (second color band)
\( band3 \) — Multiplier (third color band)

Explanation: The first two bands represent digits that form a two-digit number, which is then multiplied by 10 raised to the power of the third band's value.

3. Importance of Resistor Color Codes

Details: Color coding allows for quick identification of resistor values even when printed text would be too small to read. It's an international standard used on most through-hole resistors.

4. Using the Calculator

Tips: Select the colors of each band from the dropdown menus. The first two bands are digits (0-9), while the third band is the multiplier (10^-2 to 10^9).

5. Frequently Asked Questions (FAQ)

Q1: What about 4-band or 5-band resistors?
A: This calculator handles 3-band resistors. For 4-band resistors, the formula is similar but includes a tolerance band. For 5-band resistors, the first three bands are digits.

Q2: How accurate are resistor color codes?
A: The color code itself is precise, but actual resistor values have tolerances (typically ±5% or ±10%) which aren't shown in this 3-band version.

Q3: What do gold and silver bands mean?
A: In the multiplier position, gold means ×0.1 and silver means ×0.01. When they appear as the fourth band, they indicate tolerance (gold = ±5%, silver = ±10%).

Q4: Why do some resistors start with black band?
A: Black as first digit means 0, which is unusual but possible in some specialized applications. Normally resistors don't start with 0.

Q5: How do I read resistors with more bands?
A: For 4 bands: first two are digits, third is multiplier, fourth is tolerance. For 5 bands: first three are digits, fourth is multiplier, fifth is tolerance.