Resistor Calculator
The following are tools to calculate the ohm value and tolerance based on resistor color codes, the total resistance of a group of resistors in parallel or in series, and the resistance of a conductor based on size and conductivity.
Resistor color code calculator
Use this calculator to find out the ohm value and tolerance based on resistor color codes.
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Parallel resistor calculator
Provide all of the resistance values in parallel, separated by a comma "," and click the "Calculate" button to determine total resistance.
Resistors in series calculator
Provide all of the resistance values in series separated by a comma "," and click the "Calculate" button to determine total resistance.
Resistance of a Conductor
Enter the data below to determine a conductor’s resistance. The tool works under the assumption that the conductor has a circular cross‑section.
Resistor Color Code
An electronic color code provides a way to denote the specifications of various components—most commonly the resistance of a resistor measured in ohms. While the scheme can also be applied to capacitors, inductors, diodes and other parts, this calculator focuses solely on resistors.
How the color coding works:
Resistor color bands follow the international IEC 60062 standard. The table you’ll see lists colors that correspond to significant figures, multipliers, tolerance, reliability and temperature coefficient. The meaning of a given hue depends on its position on the component. In a standard four‑band resistor a gap separates the third and fourth bands, indicating that the reading proceeds from left to right, with the lone band after the gap being the right‑most one. The example below illustrates such a four‑band part; additional variants are discussed later.
Significant figure component:
For a typical four‑band resistor the first two strips denote the significant digits. In the illustration above the bands are green, red, blue and gold; according to the chart, green corresponds to 5 and red to 2.
Multiplier:
The third stripe, colored blue, serves as the multiplier. Referring to the table, this band represents a factor of 1 000 000. Multiplying this factor by the previously obtained digits (52) yields 52 000 000 Ω, or 52 MΩ.
Tolerance:
The optional fourth stripe indicates tolerance. In the example a gold band signals a tolerance of ±5 % (letter J). Consequently the 52 MΩ figure may vary between 49.4 MΩ and 54.6 MΩ.
Reliability, temperature coefficient, and other variations:
Components that use color codes contain a minimum of three bands: two for significant figures and one for the multiplier, though many other configurations exist. Military‑grade parts, for instance, often employ four bands and may add a fifth to convey reliability as a failure‑rate percentage per 1 000 hours. A fifth band can also denote the temperature coefficient, expressed in ppm/K.
Five‑band resistors are common when higher accuracy is needed, thanks to an additional significant‑figure band. This pushes the multiplier and tolerance bands into the fourth and fifth positions, respectively, compared with the standard four‑band layout.
The most exacting resistors may feature a sixth band. Here the first three bands give the significant figures, the fourth the multiplier, the fifth the tolerance, and the sixth can represent either reliability or temperature coefficient. Various other band arrangements also occur, but these are among the most frequently seen.
| Color | 1st, 2nd, 3rd Band Significant Figures |
Multiplier | Tolerance | Temperature Coefficient |
| 0 | × 1 | 250 ppm/K (U) | ||
| 1 | × 10 | ±1% (F) | 100 ppm/K (S) | |
| 2 | × 100 | ±2% (G) | 50 ppm/K (R) | |
| 3 | × 1K | ±0.05% (W) | 15 ppm/K (P) | |
| 4 | × 10K | ±0.02% (P) | 25 ppm/K (Q) | |
| 5 | × 100K | ±0.5% (D) | 20 ppm/K (Z) | |
| 6 | × 1M | ±0.25% (C) | 10 ppm/K (Z) | |
| 7 | × 10M | ±0.1% (B) | 5 ppm/K (M) | |
| 8 | × 100M | ±0.01% (L) | 1 ppm/K (K) | |
| 9 | × 1G | |||
| × 0.1 | ±5% (J) | |||
| × 0.01 | ±10% (K) | |||
| ±20% (M) |
Resistors are passive components that introduce electrical resistance into a circuit. Though circuits can become quite intricate, resistors within them can usually be categorized as being wired in series or in parallel.
Resistors in parallel:
When resistors are connected in parallel, the overall resistance is calculated as the reciprocal of the sum of the reciprocals of the individual resistances. See the formula below for details.
| Rtotal = |
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Resistors in series:
Resistors wired in series simply add together, so the total resistance equals the sum of each resistor’s resistance. The equation that follows demonstrates this.
Rtotal = R1 + R2 + R3 ... + Rn
Resistance of a conductor:
| R = |
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Where:
L is the length of the conductor
A is the cross-sectional area of the conductor
C is the conductivity of the material