1. What is an SMD Resistor Value Calculator?

Definition: This calculator determines the resistance value of surface-mount device (SMD) resistors based on their 3-digit code.

Purpose: It helps electronics engineers, technicians, and hobbyists quickly decode SMD resistor markings.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( R \) — Resistance value (ohms)
• \( digit1 \) — First significant digit (0-9)
• \( digit2 \) — Second significant digit (0-9)
• \( multiplier \) — Power of ten multiplier (-2 to 9)

Explanation: The first two digits form the significant figures, which are multiplied by 10 raised to the power of the third digit.

3. Importance of SMD Resistor Codes

Details: SMD resistors are too small for color bands, so they use numerical codes. Understanding these codes is essential for circuit design and repair.

4. Using the Calculator

Tips: Enter the first two digits (0-9) and the multiplier exponent (-2 to 9). For example, "103" would be 10 × 10³ = 10,000Ω.

5. Frequently Asked Questions (FAQ)

Q1: What does "R" mean in SMD codes?
A: "R" represents a decimal point. For example, "4R7" means 4.7Ω.

Q2: How are values below 10Ω represented?
A: With an "R" for the decimal point or with a negative multiplier (e.g., 100 = 10 × 10⁰ = 10Ω, 10R0 = 10.0Ω).

Q3: What about 4-digit SMD codes?
A: 4-digit codes work similarly but with three significant digits (e.g., 1002 = 100 × 10² = 10,000Ω).

Q4: How do I identify small resistors?
A: The smallest packages (0402, 0201) may have no markings - you'll need to measure them.

Q5: What's the typical tolerance of SMD resistors?
A: Most are 1% or 5% tolerance, unless otherwise specified by additional markings.