IR LED Resistor Calculator
Infrared emitter resistors — low 1.4 V forward drop, pulsed-vs-continuous ratings and why your remote drives its LED at 10× 'maximum'.
Preset: continuous 60 mA from 5 V → 56 Ω at 0.22 W (use a ½ W part). For remote-style pulsing, design at the PULSED current via a transistor — the resistor math is identical, just braver.
IR LED Resistor Calculator computes resistors for infrared emitters — low 1.4 V forward drop, continuous vs pulsed ratings — free, instant and private in your browser. Remote-control, beam-break and night-vision builders working with invisible light use it to skip the datasheet algebra: type your numbers, read the answer with the substituted formula shown step by step, and share an exact permalink of the calculation.
About IR LED Resistor Calculator
IR LED Resistor Calculator computes resistors for infrared emitters — low 1.4 V forward drop, continuous vs pulsed ratings using the standard engineering relation: R = (Vs − 1.4)/If; the low Vf puts MOST of the supply across the resistor — check its wattage. Worked live: 60 mA continuous from 5 V wants 56 Ω dissipating 0.22 W — a ½ W part, not a ¼ W. The result recalculates on every keystroke, the worked-example panel shows your numbers substituted into the formula, and the Copy permalink button encodes the inputs in the URL so a colleague opens exactly your calculation. Everything runs client-side — nothing you type leaves your device.
How to use IR LED Resistor Calculator
- 1Enter your values — the tool starts with realistic defaults for this exact use case, so the worked example is meaningful immediately.
- 2Read the live result and the worked-example panel, which substitutes your numbers into the formula step by step.
- 3Adjust any input to compare scenarios, then use Copy result or Copy permalink to share the calculation.
Why use IR LED Resistor Calculator?
- ✓Implements the real formula — R = (Vs − 1.4)/If — with the substitution shown, not a black box
- ✓Built for remote-control, beam-break and night-vision builders working with invisible light
- ✓Copy result and permalink buttons — share the exact calculation in a README, forum answer or design review
- ✓100% free, no sign-up, runs entirely in your browser (works offline once loaded)
Frequently asked questions
How do you calculate ir led resistor?+
Resistors for infrared emitters — low 1.4 V forward drop, continuous vs pulsed ratings follows R = (Vs − 1.4)/If; the low Vf puts MOST of the supply across the resistor — check its wattage. For example, 60 mA continuous from 5 V wants 56 Ω dissipating 0.22 W — a ½ W part, not a ¼ W. The calculator applies the same relation and shows the substituted arithmetic so you can verify every step.
How do I see whether an invisible IR LED is actually on?+
Point a phone's FRONT camera at it — most front cameras lack a strong IR filter and show the LED as a violet-white glow (rear cameras often filter it; try both). In-circuit, a diode-mode meter reading ~1.2–1.4 V confirms the junction is conducting.
How do TV remotes drive their IR LED at 10× the 'maximum' current?+
Duty cycle. Datasheets allow brief, huge pulses — e.g. 100 mA continuous but 1 A pulsed under 100 µs at low duty. A remote's 38 kHz burst structure keeps average power tiny while instantaneous optical output (which sets range) is enormous. Drive via a transistor and respect the pulse-rating curve.
Is the IR LED Resistor Calculator free and private?+
Yes — completely free with no sign-up or usage limits, and it runs entirely in your browser: the values you enter are never uploaded or stored on a server.
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