1. What is an SMD Resistor 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 values for circuit design and repair.

2. How Does the Calculator Work?

The calculator uses the formula:

Where:

• \( R \) — Resistance value in ohms (Ω)
• \( digit1 \) — 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, and the multiplier determines the magnitude.

3. Importance of SMD Resistor Codes

Details: SMD resistors are marked with numeric codes due to their small size. Understanding these codes is essential for proper component selection and circuit troubleshooting.

4. Using the Calculator

Tips: Enter the first two digits (0-9) and the multiplier (-2 to 9). Common multipliers include 0 for 1Ω-9.9Ω, 1 for 10Ω-99Ω, 2 for 100Ω-990Ω, etc.

5. Frequently Asked Questions (FAQ)

Q1: What does a "222" code mean?
A: 222 = 22 × 10² = 2200Ω or 2.2kΩ

Q2: How are values below 10Ω represented?
A: Using R for decimal point (e.g., 4R7 = 4.7Ω) or negative multipliers (e.g., 100 = 10 × 10⁰ = 10Ω).

Q3: What about 4-digit SMD codes?
A: 4-digit codes use the same principle but with three significant digits (e.g., 1002 = 100 × 10² = 10kΩ).

Q4: How do I identify tolerance?
A: Standard SMD resistors are typically ±5% (no code) or ±1% (marked with "01D" where D is multiplier).

Q5: What's the smallest SMD resistor size?
A: 01005 (0.4mm × 0.2mm) is the smallest common size, though these often use special marking systems.