A familiar situation
Bestimmen Sie den Widerstand eines Bauteils anhand der Farbringe oder dimensionieren Sie einen einfachen LED-Vorwiderstand.
How to use this calculator
- Enter calculation, band 1, band 2 and the remaining inputs.
- Select Calculate to see the answer and its breakdown.
- Keep a scenario, change an input and compare the results.
Use consistent units and check the assumptions below before applying the result.
How resistor is calculated
Decode a four-band resistor color code into nominal resistance and tolerance, or calculate a series resistor for an LED from supply voltage, LED forward voltage, and target current. The current-limiting calculation is idealized; choose a standard value and check resistor power dissipation. Red-violet-brown-gold represents 270 Ω ±5%. The calculation validates each input and keeps its stated units explicit. No. It gives nominal resistance and tolerance; actual resistance can vary within that range. This is an estimate for the stated assumptions; confirm measurements and any applicable professional or local standards before relying on it.
Resistor Calculator is calculated from the supplied measurement fields using the units shown.Red-violet-brown-gold represents 270 Ω ±5%.
Assumptions & useful context
The result depends on the values you enter and the method described above. Displayed numbers may be rounded; calculations use the unrounded values. Check that this model matches your situation before relying on it.
Frequently asked questions
Can a color code tell the exact measured value?
No. It gives nominal resistance and tolerance; actual resistance can vary within that range.
Why check resistor wattage?
The resistor dissipates electrical power as heat and must be rated for the load with suitable margin.