22 Best Free Online LED Resistor Calculator Websites

Here is a list of the best free online LED resistor calculator websites. Generally, you have to add a resistor between the source voltage and an LED. This is because an LED light takes very little current. Connecting an LED directly to a voltage source like a battery can burn the LED right away. Even a slightly higher current can make the LED shine beyond its limit leading to a shorter LED life cycle. So adding a resistor between the LED and the source is necessary. This can provide the LED with the right amount of current without harming it in any way.

A LED resistor calculator can help you find the right resistor value that you should use for an LED or a series of LEDs. You can provide the source voltage, LED current, and LED voltage drop (or LED color) to get the resistor value. This post covers 22 free websites with LED resistor calculators. You can use these calculators to find the right resistor value for your LED circuit. Some of these calculators also work for multi-LED circuits connected in series or parallel. You can go through the post to check them out in detail.

My Favorite Online LED Resistor Calculator

Hobby-Hour.com is my favorite website on this list to calculate LED resistor online. This calculator helps you find the right resistor value for an LED circuit connecting in series or parallel. Along with the right resistor value, it also gives you the nearest lower and nearest higher resistors. And, it also generates a schematic of the LED circuit. This calculator has a detailed explanation of all the terms and procedures. This can come in handy for newbies to have an in-depth understanding of the circuit.

You can also check out our lists of the best free Parallel Resistance Calculator Online Websites, Resistor Color Code Calculator For Windows, and Circuit Builder App For Android.

Hobby-Hour.com

Hobby-Hour.com has a free online LED resistor calculator. This calculator helps you find out the right resistor value for your LED circuit. It can calculate the resistor for a circuit with 1 to 20 LED lights. It works for both types of circuits where LEDs are connected in series and parallel. This calculator comes with a “Resistor precision” option. This lets you define a precision percentage for the calculation. When you do that, the final output gives you the nearest lower resistor and the nearest higher resistor with the input precision percentage. Along with that, it also generates a schematic of the LED circuit.

Highlights:

Input: Supply Voltage, LED Current, Voltage Drop (LED Color), No. of LEDs, and Resistor precision.
Output: Resistance, Power dissipated by the resistor, Recommended resistor Wattage, Power consumed by the LED, Total power consumption, and Efficiency.
LED Connection: Series or Parallel LED connections.
Circuit Diagram: Generates schematics.

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OmniCalculator.com

OmniCalculator.com also has a free online LED resistor calculator. This calculator works for LEDs connected in series as well as LEDs connected in parallel. You can pick the mode at the top of the calculator. After that, you can simply add the required values to the calculator. When it comes to LED voltage, you can either pick the LED color to fetch the LED voltage automatically. Or, you can enter the LED voltage directly yourself. With all the required input, this calculator gives you the resistance required in the circuit. Along with that, it also calculates the power dissipation in a single LED, in all LEDs, and in the resistor.

Highlights:

Input: Supply Voltage, LED Voltage, LED Current, and No. of LEDs.
Output: Resistance required and Power Dissipation.
LED Connection: Single LED, LEDs in Series, or LEDs in Parallel.
Circuit Diagram: No diagrams.

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Hebeiltd.com

Hebeiltd.com is a free website to calculate the resistor value for a LED circuit. This website offers three calculators for Single LED Circuit, LEDs in Series Circuit, and LEDs in Parallel Circuit. Based on your circuit, you can pick a calculator and add the required values. In the out, it tells you the resistor value that you should use in the circuit. It also gives you the nearest higher-rate resistor with 10% precision. Along with that, each calculator also calculates the resistor wattage and the power rating and generates schematics of the circuit.

Highlights:

Input: Supply Voltage, Voltage Drop, Forward Current, and No. of LEDs.
Output: Resistor Value, Nearest higher rated 10% Resistor, Resistor Wattage, and Power Rating.
LED Connection: Single LED, LEDs in Series, and LEDs in Parallel.
Circuit Diagram: Generates schematics.

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CircuitDigest.com

CircuitDigest.com is another free website with an online LED resistor calculator. This calculator works with single LED circuits and circuits with multiple LEDs connected in series. It has an option to pick the LED color. Based on that, it automatically calculates the forward voltage. Then you just have to add the source voltage, current, and number of LEDs. With that, it gives you resistance along with resistor wattage.

Highlights:

Input: Supply Voltage, Forward Voltage (LED Color), Forward Current, and No. of LEDs.
Output: Resistor Value, Nearest higher rated 10% Resistor, Resistor Wattage, and Power Rating.
LED Connection: Single LED and LEDs in Series.
Circuit Diagram: Has general circuit schematics.

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EasyCalculation.com

EasyCalculation.com offers a free online LED resistor calculator. This calculator has two sections; LED Parallel Resistance and LED Series Resistance. As per your circuit, you can pick the desired section to calculate the resistor value. In the case of a single LED circuit, you can use any of the calculators by keeping the number of LEDs to 1. Both these calculators have an option to pick the LED color. You can either use that or manually enter the LED voltage. In the output, it gives you the resistance along with recommended resistor (nearest lower 10%), recommended resistor (nearest higher 10%), and resistor wattage.

Highlights:

Input: Supply Voltage, LED Voltage, LED Current, and No. of LEDs.
Output: Resistor Value, Nearest higher Resistor Value, Nearest lower Resistor Value, and Resistor Wattage.
LED Connection: Single LED, LEDs in Series, and LEDs in Parallel.
Circuit Diagram: No diagram.

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AllAboutCircuits.com

AllAboutCircuits.com offers a free online LED resistor calculator. This calculator determines the resistor value you need for a LED circuit. It works for circuits where LEDs are connected in series. You can pick the number of LEDs in your circuit and add the supply voltage and forward current. For forward voltage, you can simply select the LED color that you are using. Based on the color and number of LEDs, this calculator determines the forward voltage and then gives you the resistor value you are going to need for the circuit to work nominally.

Highlights:

Input: Supply Voltage, Forward Voltage, Forward Current, and No. of LEDs.
Output: Resistor Value, Resistor Power dissipation, and Recommended resistor Wattage.
LED Connection: LED connected in series.
Circuit Diagram: Generates schematics.

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PCBoard.ca

PCBoard.ca offers a free online LED Dropping Resistor Calculator. It actually has two calculators for single LED circuits and Multiple LED Circuits. The “One Single LED” calculator takes the required values and gives you the value of the limiting resistor for the circuit. And the “Two or More LEDs” calculator does the same with an additional input parameter for the number of LEDs. Along with the limiting resistor value, it also gives you the nearest standard resistor value, resistor wattage, and safe power rating.

Highlights:

Input: Supply Voltage, LED Voltage, LED Current, and No. of LEDs.
Output: Resistor Value, Nearest Standard Resistor Value, Resistor Wattage, and Safe Power Rating.
LED Connection: Single LED and LEDs in Series.
Circuit Diagram: Shows wiring diagrams of both types of circuits.

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OhmsLawCalculator.com

OhmsLawCalculator.com has a free online LED resistor calculator that you can use. This calculator helps you find the resistor value for a LED circuit. This works for LEDs connected in series or in parallel. It does not have an option to select the number of LEDs. Since it requires voltage drop due to LEDs, you can use it for any number of LEDs. All you have to do is calculate the voltage drop based on the number of LEDs and how those LEDs are connected. With that, this calculator gives you the resistor value. It also shows the LED power in the output.

Highlights:

Input: Supply Voltage, Voltage Drop, and Forward Current.
Output: Resistor Value and LED Power.
LED Connection: LED connected in series or parallel.
Circuit Diagram: Generates schematics.

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EngineersEdge.com

EngineersEdge.com offers a unique online LED resistor calculator. You can use this calculator for circuits with multiple strings of LEDs. A string contains multiple LEDs connected in series. And then the strings are connected in parallel with the voltage source. There is a resistor in each string of the LEDs. So the voltage stays the same for all the strings. You just have to calculate the resistor for each string of LEDs. This is a regular calculator where you have to add the LED voltage, LED current, and number of LEDs for each string. This gets you the value of the resistor for each LED string. You can add a resistor of calculated value in the respective string and have a working LED circuit.

Highlights:

Input: Supply Voltage, LED Voltage, LED Current, and No. of LEDs.
Output: Resistor Value for each string.
LED Connection: LEDs in Series.
Circuit Diagram: Shows wiring diagrams of the circuit.

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DigiKey.in

DigiKey.in is a free website with an online LED resistor calculator. This is a simple calculator designed for a circuit with one or more LEDs connected in series. Instead of asking for LED color or voltage drop, it asks for forwarding voltage and forwards current. Depending on the number of LEDs in the series, you can find these values based on LED color and add those to the calculator. In the output, it gives you the recommended resistor value along with power. Do note that, this website recommends picking a device with a 2 to 10 power rating from the calculated value. This is to avoid the resistor from getting too hot.

Highlights:

Input: Supply Voltage, Forward Current, and Forward Voltage.
Output: Resistor value and Power.
LED Connection: LED series circuit.
Circuit Diagram: Generates schematics.

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Make-it.ca

Make-it.ca offers a set of online LED resistor calculators that you can use for free. It has two calculators for Single LED Circuits and LEDs in Series Circuits. Each calculator shows a wiring diagram. As per your circuit, you can pick the right calculator and add all the required values. In the case of LEDs in a series circuit, add the number of LEDs in the circuit. For the input values, both these calculators give you the resistor value, nearest standard resistor value, resistor wattage, and safe power rating.

Highlights:

Input: Supply Voltage, Forward Voltage, LED Current, and No. of LEDs.
Output: Resistor Value, Nearest Standard Resistor Value, Resistor Wattage, and Power Rating.
LED Connection: Single LED and LEDs in Series.
Circuit Diagram: It shows a wiring diagram of the circuit.

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nCalculators.com

nCalculators.com offers a multi-purpose LED resistor calculator. This calculator has a dropdown toggle at the top from where you can switch between Series LED Resistor and Parallel LED Resistor. You can pick the mode as per your circuit. Then you can simply add the required parameters to the calculator. This includes supply voltage, the voltage drop across LEDs, LED current, and the number of LEDs. After that, you can simply click the “Calculate” button to get the resistor value along with resistor wattage.

Highlights:

Input: Supply Voltage, LED Voltage (LED Color), LED Current, and No. of LEDs.
Output: Resistor Value and Resistor Wattage.
LED Connection: A Single LED and Multiple LEDs (Series and Parallel).
Circuit Diagram: No diagrams.

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LEDCalculator.net

LEDCalculator.net is a simple online LED resistor calculator. This calculator asks for power supply voltage, LED drop voltage, LED current, and the number of LEDs. You can keep the LEDs number to 1 for a single LED circuit. Otherwise, you can add the desired number of LEDs for a circuit with LEDs in series. Based on the input, it tells you the resistor value for the circuit. Instead of showing the value directly, this calculator generates a wiring diagram or schematic. You can pick what you want to generate. And it shows the resistor value in the diagram. From there, you can also print the diagram into a PDF.

Highlights:

Input: Supply Voltage, LED Drop Voltage, LED Current, and No. of LEDs.
Output: Resistor Value, Nearest Standard Resistor Value, Resistor Wattage, and Power Rating.
LED Connection: Single LED and LEDs in Series.
Circuit Diagram: Generates printable Wiring Diagram and Schematics of the circuit.

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ElectricalTechnology.org

ElectricalTechnology.org is another free website to calculate LED resistor online. This website features a simple calculator. You can use this calculator to determine the resistor value for a single LED circuit. To do that, you have to provide the source voltage, forward LED voltage, and LED current. If you don’t know the LED voltage, you can refer to an online chart to get the LED voltage based on the LED color. When you add all the values and press the “Calculate” button, it shows you the required resistor value on the screen.

Highlights:

Input: Supply Voltage, LED Voltage, and LED Current.
Output: Resistor Value.
LED Connection: Single LED Circuit.
Circuit Diagram: No diagram.

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Mouser.com

Mouser.com is a free website with an online LED Series Resistor Calculator. You can use this calculator to determine the required resistor value in a LED circuit. This calculator asks for supply voltage, forward voltage, and forward current. There is no option to pick the LED color or enter the number of LEDs. That means it works for single LED circuits and circuits with multiple LEDs in series. However, you have to manually calculate the voltage drop across LEDs and enter that value in the forward voltage field. With that, this calculator gives you the required resistor value along with LED power.

Highlights:

Input: Supply Voltage, Forward Voltage, and Forward Current.
Output: Resistor Value and LED Power.
LED Connection: LED connected in series.
Circuit Diagram: No diagrams.

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LuxaLight.eu

LuxaLight.eu has a free online LED resistor calculator. This calculator works for LEDs connected in series. You can also use it for a single LED circuit. This calculator has a bar of colors at the top. This represents the LED colors. You can pick a color to add the respective LED voltage to the calculator. Alternatively, you can manually enter the LED voltage. Then you can all the remaining parameters along with the number of LEDs. This gets you the required resistor value for the circuit. This calculator also gives you some other calculations including rounded standard E12 value, rounded power using a standard 5% resistor, the real current through the E12 resistor, and power dissipation.

Highlights:

Input: Supply Voltage, LED Voltage (or LED Col0r), LED Current, and No. of LEDs.
Output: Resistance required, Rounded standard E12 value, Rounded Power using standard 5% resistor, Real current through the E12 resistor, Dissipated Power in the LED, and Dissipated Power in the resistor.
LED Connection: Single LED or LEDs in Series.
Circuit Diagram: No diagrams.

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CalculatorHut.com

CalculatorHut.com offers a free online LED resistor calculator. You can use this calculator for a single LED circuit as well as multiple LED circuits. At the beginning of the calculator, you get an option to pick the LED color. Simply select a color as per your LEDs in the circuit. Doing this automatically loads the LED voltage into the calculator. After that, you can fill in the other parameters along with the number of LEDs in the circuit. With that, this calculator finds you the resistor value. Along with that, it also gives you the resistor wattage.

Highlights:

Input: Supply Voltage, LED Voltage (LED Color), LED Current, and No. of LEDs.
Output: Resistor Value and Resistor Wattage.
LED Connection: A Single LED and Multiple LEDs.
Circuit Diagram: No diagrams.

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CalcTown.com

CalcTown.com is another free website with a simple online LED resistor calculator. With the help of this calculator, you can find the resistor value that you should use in a single LED circuit. It needs the source voltage, LED voltage, and LED current. With those three values, it gets you the resistor value in Ohms. You have to use a resistor of that value to limit the current and have a nominal single LED circuit.

Highlights:

Input: Supply Voltage, LED Voltage, and LED Current.
Output: Resistor Value.
LED Connection: A Single LED Circuit.
Circuit Diagram: No diagrams.

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InchCalculator.com

InchCalculator.com is a free website that offers a wide collection of online calculators for various topics. It has a LED Resistor Calculator that you can use to determine the value of the resistor in an LED circuit. You can use this calculator for circuits with a single LED or multiple LEDs. To do that, you can start by picking the LED color. This automatically fills the LED voltage in the calculator. Then you can add the source voltage, LED current, and the number of LEDs in the circuit. This gets you the resister value along with resistor wattage.

Highlights:

Input: Supply Voltage, LED Voltage (or LED Col0r), LED Current, and No. of LEDs.
Output: Resistor Value and Resistor Wattage.
LED Connection: Single LED or Multiple LEDs.
Circuit Diagram: No diagrams.

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PhysicsCalc.com

PhysicsCalc.com is another free website that you can use to calculate LED resistor online. This website has a multi-purpose calculator based on Ohm’s Law. You can use this calculator to find one of the following parameters when the other three parameters are known; Resistance, Source Voltage, LED Voltage, and LED Current. It works for a single LED circuit. To calculate resistance, you can fill all the other known values and get the resistor value in the output.

Highlights:

Input: Supply Voltage, LED Voltage, and LED Current.
Output: Resistor Value.
LED Connection: A Single LED Circuit.
Circuit Diagram: No diagrams.

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Codeduino.com

Codeduino.com has a free LED resistor calculator that you can use online. This is a simple calculator that works for LED circuits with one LED. With the help of this calculator, you can find the resistor value that you should add between the LED and the voltage source to limit the current flow. To do that, you have to add the source voltage, LED voltage, and LED current into the calculator. When you run the calculator with compatible inputs, it gives you the resistor value that you should use in the circuit.

Highlights:

Input: Supply Voltage, LED Voltage, and LED Current.
Output: Resistor Value.
LED Connection: A Single LED Circuit.
Circuit Diagram: No diagrams.

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CalculatorPro.com

CalculatorPro.com is yet another website with a free online LED resistor calculator. This calculator can help you determine the resistor value needed for a single LED circuit. To do that, you just have to enter the required parameters into the calculator. The parameters you need to know are the source voltage, the forward voltage (LED voltage), and the LED current. Enter these three parameters into the calculator then click the “Calculate” button and wait for a few seconds. This gets you the value of the resistor on the screen. You have to use a resistor of the given value in your single LED circuit.