1. What is an SMD Resistor Calculator?

Definition: This calculator determines the resistance value of SMD (Surface Mount Device) resistors based on their 3-digit or 4-digit code.

Purpose: It helps electronics engineers, technicians, and hobbyists quickly decode SMD resistor markings without memorizing coding schemes.

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 (exponent)

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

3. Importance of SMD Resistor Coding

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 (typically -2 to +9). For example, "103" would be 1, 0, 3 = 10 × 10³ = 10kΩ.

5. Frequently Asked Questions (FAQ)

Q1: What about 4-digit SMD codes?
A: For 4-digit codes (E96 series), use digit1, digit2, digit3 as the significant figures (R = (digit1×100 + digit2×10 + digit3) × 10^multiplier).

Q2: How are small values represented?
A: Values below 10Ω use 'R' for decimal point (e.g., 4R7 = 4.7Ω).

Q3: What's the tolerance of SMD resistors?
A: Standard 3-digit codes are typically ±5%, while 4-digit (E96) are ±1%.

Q4: How do I read milliohm resistors?
A: They use 'm' instead of 'R' (e.g., 1m00 = 1.00mΩ).

Q5: What about letter codes?
A: Some manufacturers use proprietary letter codes - consult their datasheets.