led resistor — free browser tool | fatcousin

current-limit resistor for an led · single · series · parallel · array · runs locally

disclaimer · read before using results

ideal-component model. ignores resistor tolerance, led forward-voltage variation between samples, thermal drift of vf with junction temperature, and supply ripple · standard-tier wattage suggestion uses a 2× margin over computed dissipation, surfaced as a number, not a verdict · for high-current, automotive, or thermally constrained builds, treat this as a starting point and confirm against the led datasheet.

topology

one led with one resistor in series

led + supply

supply voltage (V)led forward voltage Vf (V)led forward current If (mA)

result

resistor (per branch)

495.0 Ω

exact value · across 9.900 V

nearest e12

560.0 Ω

standard value at-or-above exact

resistor power (each)

198.0 mW

pick ≥ 500.0 mW tier (2× margin)

resistors needed

leds

headroom

9.900 V

supply − N · Vf

total current

20.00 mA

from the supply

total supply power

240.0 mW

dissipation split

18% / 83%

leds / resistors

status

>ready