The 4-band color code for a standard 250 ohm resistor (5% tolerance) is Red, Green, Brown, Gold. For a precision 1% tolerance 5-band resistor, the sequence is Red, Green, Black, Black, Brown. In surface-mount (SMD) format, the 3-digit code is 251.
While home wiring relies on regional electrical codes like the US NEC or IEC 60446, through-hole resistor color codes are governed globally by component standards. Below is the complete breakdown of how to read, verify, and troubleshoot the 250 ohm value across different package types and legacy standards.
The 250 Ohm Resistor Encoding Reference
The value 250 is a standard base number in the E24 resistor series. Because it is an E24 value, it is widely manufactured in both 5% and 1% tolerances. The table below maps the exact physical markings you will see on the bench for a 250 Ω component.
| Format | Bands / Characters | Exact Sequence | Math / Logic | Typical Use Case |
|---|---|---|---|---|
| 4-Band (5%) | 4 Colors | Red, Green, Brown, Gold | 25 × 101 = 250 Ω | General purpose, pull-ups, LED limiting |
| 5-Band (1%) | 5 Colors | Red, Green, Black, Black, Brown | 250 × 100 = 250 Ω | Precision analog, feedback loops, sensors |
| 6-Band (1% + Tempco) | 6 Colors | Red, Green, Black, Black, Brown, [Tempco] | 250 × 100 + TCR band | High-stability audio or RF circuits |
| SMD 3-Digit (5%) | 3 Numbers | 251 | 25 × 101 = 250 Ω | 0805, 1206, and larger SMD footprints |
| SMD 4-Digit (1%) | 4 Numbers | 2500 | 250 × 100 = 250 Ω | 1206 and larger precision SMD footprints |
To decode these, you rely on the standard IEC 60062 color chart. For the 250 ohm value specifically, you only need to memorize four colors: Red (2), Green (5), Black (0 / ×1), and Brown (×10 / 1%), plus Gold (5%) for standard tolerance.
Standard Variants: IEC 60062 vs. Legacy and Military Specs
Modern through-hole resistors universally follow IEC 60062 for color band encoding. However, if you are repairing vintage gear or working with military surplus, you will encounter regional and standard variants that deviate from the modern band layout.
| Standard | Region / Origin | Marking Style | 250 Ohm Example | Where You Will Find It |
|---|---|---|---|---|
| IEC 60062 | Global (Modern) | 4, 5, or 6 concentric color bands | Red-Green-Brown-Gold | All modern commercial electronics |
| BS1852 (Legacy) | UK / Europe (Pre-1990s) | Body-End-Dot printing system | Red body, Green end, Brown dot | Vintage British audio amps, old test gear |
| MIL-PRF-55342 | US Military | Standard bands + 6th reliability band | Red-Green-Brown-Gold + [Reliability] | Aerospace, defense, and surplus chassis |
| EIA-96 (SMD) | Global (Precision SMD) | 2 digits + 1 letter (Lookup table) | 249 Ω is the E96 standard (Code 38C) | Dense 0402/0603 precision SMD boards |
A note on E96 SMD values: In the strict E96 (1%) series, 250 is not a base value; 249 ohms is the standard equivalent. If you are replacing a 1% SMD resistor in a precision circuit and cannot find a 2500 (4-digit) marking, look for the EIA-96 code 38C (where 38 = 249, and C = ×100).
Bands and Rows People Get Wrong
When reading the standard resistor color chart, specific rows and visual overlaps cause the most misidentifications on the workbench. Here is how to avoid the most common traps when identifying a 250 ohm resistor.
- Row 2 (Red) vs. Row 3 (Orange): Under UV exposure or high heat, red band paint degrades and shifts toward orange. If your "Red" first band looks slightly yellowish, you might misread a 250 Ω (Red-Green-Brown) as a 350 Ω (Orange-Green-Brown). Always verify with a meter if the red looks washed out.
- Row 5 (Green) vs. Row 6 (Blue): On cheap carbon film resistors, the green second digit can appear teal or dark blue under fluorescent bench lighting. A 250 Ω misread as a 260 Ω (Red-Blue-Brown) will skew your bias voltages.
- Multiplier vs. Digit Confusion: In a 4-band 250 Ω resistor, the third band is Brown (×10). In a 5-band 1% resistor, the third band is Black (0) and the fourth is Black (×1). People frequently read 5-band resistors left-to-right as 4-band, ignoring the extra significant digit. If a 5-band resistor has a Brown band on the far right (1% tolerance), read it right-to-left to establish your starting point.
Safe Interpretation When Markings Are Faded or Missing
Color codes are merely a visual aid; they are not a substitute for electrical verification. When a resistor has been subjected to thermal stress, conformal coating, or physical abrasion, the paint bands become unreliable. Follow this bench protocol to safely interpret and verify the component.
- Isolate the Component: Never trust an in-circuit multimeter reading for a definitive resistance value. Parallel paths through semiconductors and other resistors will always pull the measured value lower than the actual resistance. If your 250 Ω resistor reads 180 Ω in-circuit, it might be fine, or it might be shorted.
- Lift One Leg: If desoldering the entire component is impractical, use a soldering iron and tweezers to lift just one leg of the resistor out of its PCB pad. This breaks the parallel circuit and allows your digital multimeter (DMM) to measure the component in isolation.
- Check for Thermal Drift: If the resistor is hot to the touch, let it cool to room temperature (20°C - 25°C) before measuring. Carbon composition and thick-film resistors have positive temperature coefficients; a 250 Ω resistor might read 265 Ω while hot but settle back to 251 Ω when cool.
- Verify the Tolerance Band: If the value measures exactly 249.8 Ω, you are likely looking at a 1% metal film resistor (5-band) where the final Gold or Brown tolerance band has rubbed off. If it measures 261 Ω, it is likely a 5% carbon film resistor that has drifted out of spec due to age or moisture ingress and should be replaced.
By relying on the IEC 60062 standard sequences and verifying with a DMM out-of-circuit, you eliminate the guesswork inherent in faded paint and ambiguous SMD stampings.
