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LED Calculators
This page contains any and all calculators I can think of (or are requested)
to better help you build and compare LED lamps, understand actual light output of LEDs and help
compare them to standard incandescent lamps. You can also use this to evaluate
LED lamps you are looking at purchasing to ensure they will perform to your satisfaction
and validate lamp specs provided by sellers.
Disclaimer:
These calculators are provided AS-IS with no guarantee of accuracy.
If you do find a problem with any of the calculators, please feel free to email
me and I will fix the problem as soon as I can.
LED Resistor Calculator:
No LED calculator page would be complete without a resistor calculator. This
calculator will determine the correct resistor value given a set input voltage and
the LED current and LED voltage. Keep in mind, just because the resistance
is calculated does not mean you will be able to find a resistor with that value.
Always round up to the next available resistance. I am working on creating
a cross-reference to provide the closest available standard resistor. If you are using more than 1 LED wired IN
SERIES (end to end - output of one LED feeds the input of the next - think christmas
light string), change the default LED count to the number of LEDs in your series.
The calculator will also tell you how much wattage the resistor must be able to
handle.
Number of LEDs in series:
LED voltage:
volts
LED current:
mA
Supply voltage:
volts
Resistance needed:
Resistor size:
MCD to LUMENS converter:
Use this calculator to convert the mcd rating of an LED to its equivilent lumen
output. Since LEDs are point-source lighting, this is most helpful to compare
the total light output of one LED of a specific viewable angle to the total light
output of another LED with a different viewable angle.
mcd rating of LED:
Viewable angle of LED:
Lumens:
LUMENS to MCD converter:
Use this calculator to convert the lumen rating of an incandescent lamp to it's
equivilent mcd rating at a certain angle. Please use this as a reference only.
The actual mcd output of a reflected incandescent lamp will likely be lower then
calculated due to losses incurred in reflection and any lens that is in use.
This should not be a huge difference (unless using colored lenses) but you need
to be aware that there is a difference. I hope to have a table of actual
measured incandescent lamp light intensities in the near future for more accurate comparisons.
Lumen rating of lamp:
Output angle of lamp:
mcd:
Battery Runtime calculator (resistor limited arrays only):
Use this calculator to estimate the runtime of your LED array when connected to
a battery.
Individual battery voltage:
volts
Individual battery capacity:
mAh
Number of batteries:
Batteries are connected:
LED voltage:
volts
LED current:
mA
Resistor:
ohms
Number of LEDs per array:
Number of arrays:
Your LEDs are using:
Your resistors are using:
Calculated runtime:
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