100k Ohm Resistor Color Code — High-Z Biasing & Divider Top Leg
100 kΩ color code (Brown-Black-Yellow-Gold): high-impedance bias networks, 10 kΩ partner dividers, yellow vs orange vs green multiplier trap, and megohm-range DMM tips.
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100 kΩ: the bridge between 10 kΩ logic and megohm circuits
Brown · Black · Yellow · Gold → digits 1 · 0, multiplier ×10⁴ → 100 kΩ. This page covers high-impedance biasing and divider top legs — not GPIO pull-ups (10 kΩ guide) or full megohm measurement (1 MΩ guide).
4-band: Brown · Black · Yellow · Gold → 10 × 10,000 = 100,000 Ω = 100 kΩ (±5%) · 5-band (±1%): Brown · Black · Black · Orange · Brown → 100 × 1,000 = 100 kΩ (±1%)
Tolerance window (±5%): 95 kΩ – 105 kΩ · Band-reading method: beginner's guide · Reverse lookup: calculator
100 kΩ + 10 kΩ divider (rough 11:1 scaling)
Pair a 100 kΩ top leg with 10 kΩ to ground — a common hobby ratio for scaling a 0–5 V signal toward a 3.3 V ADC range:
| Node | Ideal $V$ @ 5 V in | Notes |
|---|---|---|
| Tap (10 kΩ to GND) | ≈ 0.45 V | High-Z load only — divider sags under current |
| Across 100 kΩ | ≈ 4.55 V | Top leg carries most of the drop |
Use our voltage divider calculator if the load draws more than nanoamps — same caution as the 1 kΩ divider guide.
Yellow vs orange vs green — the decade trap
| Value | Multiplier band | 4-band tail |
|---|---|---|
| 10 kΩ | Orange (×10³) | Brown · Black · Orange · Gold |
| 100 kΩ | Yellow (×10⁴) | Brown · Black · Yellow · Gold |
| 1 MΩ | Green (×10⁵) | Brown · Black · Green · Gold |
Swapping yellow for orange is a 10× error — common when sorting reels under poor light. Always meter high-kΩ parts out of circuit.
Where 100 kΩ shows up on real boards
| Application | Why 100 kΩ |
|---|---|
| Op-amp input bias / leak path | High enough to limit idle current, low enough vs input impedance |
| Photoresistor / NTC top leg | Forms a mid-rail tap with a lower kΩ shunt |
| Scope probe compensation (simplified) | Megohm-range networks often include 100 kΩ elements — verify schematic |
Idle current at 5 V through 100 kΩ alone: 50 µA — negligible for mains-powered prototypes, worth noting on battery nodes.
Measuring 100 kΩ accurately
- Remove from circuit — parallel paths dominate below 1 MΩ
- Use DMM 200 kΩ or 2 MΩ range as appropriate
- Avoid touching both leads — body resistance in parallel with 100 kΩ skews readings
- For ±1% parts, compare to 5-band spec — fourth band is the multiplier on 5-band reels
FAQ
What is the 100k ohm resistor color code?
4-band (±5%): Brown, Black, Yellow, Gold. 10 × 10,000 = 100 kΩ (±5%). Actual range: 95 kΩ – 105 kΩ.
What is the 100k ohm resistor colour code (5-band)?
Brown · Black · Black · Orange · Brown → 100 × 1,000 = 100 kΩ (±1%). Range: 99 kΩ – 101 kΩ.
How do I read a 100k ohm resistor color code?
Read left to right: first bands are digits, then multiplier, then tolerance. For 100 kΩ: Brown-Black-Yellow = significant digits & multiplier, Gold = tolerance. Use the color code calculator to verify.
Which end do I start reading a 100 kΩ resistor from?
Start from the grouped digit bands (left). The tolerance band (Gold) is on the right — gold and silver are almost always tolerance, not multipliers.
What is the difference between 4-band and 5-band for 100 kΩ?
4-band (Brown · Black · Yellow · Gold) gives 10 × 10,000 = 100 kΩ (±5%) with typical ±5% gold tolerance. 5-band (Brown · Black · Black · Orange · Brown) adds a third digit for ±1% precision: 100 × 1,000 = 100 kΩ (±1%) (99 kΩ – 101 kΩ).
100k vs 10k color code?
10 kΩ uses orange multiplier (×10³). 100 kΩ uses yellow (×10⁴).
Related guides (different topics)
- 10 kΩ color code — button pull-ups & NTC dividers
- 1 MΩ color code — megohm measurement & op-amp bias
- 1 kΩ color code — divider math & strong pull-ups
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Learn the method in our beginner's guide · Decode instantly with the color code calculator