Check a 1M resistor in the calculator
The calculator is set to 1 MΩ with a gold tolerance band. Switch to 5 or 6 bands, change the tolerance, or choose “Read the bands” to decode a resistor you are holding.
1M resistor colour bands
A 1 MΩ resistor carries the same value in every marking system; only the number of bands changes. Read from the end with the bands bunched closest to it, with the tolerance band, usually gold or brown and set slightly apart, on the right.
| Marking | Colours | Drawing | Where you see it |
|---|---|---|---|
| 4 bands, ±5 % | brown, black, green, gold | The most common through-hole marking | |
| 5 bands, ±1 % | brown, black, black, yellow, brown | Precision metal-film resistors | |
| 6 bands, ±1 %, 100 ppm/K | brown, black, black, yellow, brown, brown | Adds a temperature-coefficient band | |
| 3 bands, ±20 % | brown, black, green | Old parts with no tolerance band |
How to read brown, black, green, gold
- First band, brown: first digit 1.
- Second band, black: second digit 0, giving 10.
- Third band, green: multiply by 100,000, giving 1,000,000 Ω = 1 MΩ.
- Fourth band, gold: tolerance ±5 %.
On the 5-band version the first three bands are digits (100) and the fourth is the multiplier (×10,000), which comes to the same 1 MΩ. Check any other combination with the resistor color code calculator.
What a 1M resistor should measure
Tolerance is how far the real resistance may sit from the marked value. Measured out of circuit with a meter, a good 1 MΩ resistor reads within these limits:
| Tolerance | Band | Lowest | Highest |
|---|---|---|---|
| ±1 % | Brown | 990 kΩ | 1.01 MΩ |
| ±2 % | Red | 980 kΩ | 1.02 MΩ |
| ±5 % | Gold | 950 kΩ | 1.05 MΩ |
| ±10 % | Silver | 900 kΩ | 1.1 MΩ |
| ±20 % | None (no band) | 800 kΩ | 1.2 MΩ |
Measure it out of circuit, or with one leg lifted, and keep your fingers off both leads: at 1 MΩ your body’s resistance in parallel pulls the reading down noticeably.
Is 1M a standard resistor value?
Yes. 1 MΩ belongs to the E3, E6, E12, E24, E48, E96, E192 series of IEC 60063, so it is made in every tolerance from ±20 % down to ±0.1 %. The neighbouring E12 values are 820 kΩ below and 1.2 MΩ above. All the series are listed on our E-series resistor values page.
SMD code for 1 MΩ
- 3-digit code (usually ±5 %):
105. - 4-digit code (usually ±1 %):
1004. - EIA-96 code (±1 % chips in 0603 and smaller):
01E: code 1 for the digits, the letter for the multiplier.
Decode any chip marking with the SMD resistor code calculator.
Current, power and wattage
By Ohm’s law, I = V ÷ R and P = V² ÷ R. With the whole supply across a 1 MΩ resistor:
| Across | Current | Power | Rating to use |
|---|---|---|---|
| 3.3 V | 3.3 µA | 10.9 µW | ⅛ W |
| 5 V | 5 µA | 25 µW | ⅛ W |
| 12 V | 12 µA | 144 µW | ⅛ W |
| 24 V | 24 µA | 576 µW | ⅛ W |
A ¼ W 1 MΩ resistor reaches its full rating at 500 V (V = √(P × R)), but long before that it hits the maximum working voltage of a small through-hole resistor, typically 200 to 250 V, so high voltages need a higher-voltage part.
What a 1M resistor is used for
1 MΩ is a bleed and high-impedance value: it discharges filter capacitors after power-off, sets the input impedance of many oscilloscopes and amplifiers, and is the series resistor inside anti-static wrist straps, which limits the current if the wearer touches a live conductor. Capacitive touch sensing circuits use 1 MΩ and up.
Mistakes when reading a 1M resistor
The multiplier band moves the value by a factor of ten for every colour step, so it is the band to check twice, in good light. These are the misreadings that catch people out with 1 MΩ:
- Green read as blue. Brown, black, blue, gold would be 10 MΩ, 10 times too high.
- Reading the 4-band code backwards. It can’t be done: gold is not a digit colour, which is how you know which end comes first.
- Reading the 5-band code backwards. Brown, yellow, black, black, brown reads as 140 Ω ±1 %, a plausible value, so this mistake goes unnoticed. The tolerance band is usually a little apart from the others; if you can’t tell, measure it.
Making 1 MΩ from other values
No 1 MΩ in the drawer? Two common E12 values can stand in, within 1 %: in series, 180 kΩ + 820 kΩ = 1 MΩ; 330 kΩ + 680 kΩ = 1.01 MΩ; in parallel, 1.8 MΩ ∥ 2.2 MΩ = 990 kΩ. Two 1 MΩ resistors give 2 MΩ in series and 500 kΩ in parallel.
Colour codes for other common values
- 1 ohm resistor: brown, black, gold
- 100 ohm resistor: brown, black, brown
- 220 ohm resistor: red, red, brown
- 330 ohm resistor: orange, orange, brown
- 470 ohm resistor: yellow, violet, brown
- 1k resistor: brown, black, red
- 4.7k resistor: yellow, violet, red
- 10k resistor: brown, black, orange
- 100k resistor: brown, black, yellow
Colours follow IEC 60062:2016. Codes, ranges and currents on this page are computed by the same engine as the resistor colour code calculator; see our methodology.