How Many Amps Does a String of LED Lights Use Find Out Now

A typical string of LED lights uses between 0.02 and 0.1 amps, making them highly energy-efficient compared to incandescent bulbs. Actual amp draw depends on bulb count, color, and brightness settings, so always check manufacturer specs to avoid overloading circuits. Save energy and stay safe with smart LED choices!

Key Takeaways

• Check wattage first: Always find the wattage to calculate amps accurately.
• Use Ohm’s Law: Divide watts by volts to get amps easily.
• Standard strings: Most LED strings use 0.1–0.5 amps at 120V.
• Lower voltage, higher amps: 12V LEDs draw more amps than 120V ones.
• Measure with a meter: Use a clamp meter for real-time amp readings.
• Plan circuits wisely: Stay under 80% of circuit capacity for safety.
• Efficiency wins: LEDs use far fewer amps than incandescent lights.

Understanding LED Light Power Consumption

What Determines the Amp Usage of LED String Lights?

When you’re setting up holiday decorations, ambient lighting for events, or permanent installations, understanding the power consumption of your LED string lights is crucial. One of the most common questions homeowners and event planners ask is, “How many amps does a string of LED lights use?” The answer isn’t one-size-fits-all—it depends on several factors, including the number of LEDs per strand, voltage, brightness (lumens), and overall design. While traditional incandescent string lights guzzle electricity, LEDs are far more energy-efficient, but that doesn’t mean their power draw is negligible, especially when multiple strands are connected.

LEDs (light-emitting diodes) operate on low-voltage direct current (DC), but most household string lights are designed to run on standard 120-volt AC power (in the US) or 230-volt AC (in Europe). The amperage (amps) is a measure of the electrical current flowing through the circuit. Knowing the amperage helps you avoid overloading your circuits, which can lead to tripped breakers or even fire hazards. In this guide, we’ll break down how to calculate the amp draw of LED string lights, explain the variables involved, and provide practical tips for safe and efficient use.

Why Amperage Matters for LED Lighting

Amperage (A) is a key part of the Ohm’s Law equation (P = V × I, where P is power in watts, V is voltage, and I is current in amps). For example, a 24-watt LED string running on 120 volts draws about 0.2 amps. But when you connect 10 such strings end-to-end, the total draw jumps to 2 amps—still manageable, but important to track if you’re using extension cords or power strips. Exceeding the rated capacity of a circuit (typically 15 or 20 amps for standard outlets) can cause overheating and damage. LED lights are safer than incandescent bulbs, but understanding their amperage ensures you stay within safe limits while maximizing your lighting potential.

Factors That Influence LED String Light Amperage

Number of LEDs and Strand Length

The most significant factor affecting amperage is the total number of LEDs in a string. A typical 50-foot strand with 200 LEDs (4 LEDs per foot) will draw more current than a 25-foot strand with 100 LEDs. For example:

• A 50-foot string with 100 LEDs: ~0.1–0.2 amps
• A 50-foot string with 200 LEDs: ~0.2–0.4 amps
• A 100-foot string with 200 LEDs: ~0.3–0.5 amps

Note that longer strings with more LEDs often have higher resistance, which can slightly reduce efficiency, but the increase in LED count dominates the current draw. Always check the manufacturer’s specifications—some high-density LED strings (e.g., 600 LEDs on 100 feet) can draw up to 0.8 amps.

Voltage and Power Supply Design

Most residential LED string lights are designed for 120V AC input and use internal transformers or drivers to step down the voltage to 5V, 12V, or 24V DC for the LEDs. Lower-voltage strings (e.g., 12V) are often used for outdoor or landscape lighting and may draw more amps at the low-voltage end, but the wall-plug amperage remains low due to efficient conversion. For example:

• A 12V, 24-watt string: 2 amps at 12V, but only 0.2 amps at 120V input (after conversion)
• A 5V USB-powered LED string: 1 amp at 5V, but negligible draw on the USB port (5V/1A = 5W)

Always verify whether the amp rating listed on the packaging refers to input (wall plug) or output (LED circuit). Input amperage is what matters for circuit safety.

LED Type and Brightness (Lumens per LED)

Not all LEDs are created equal. A 5mm diffused LED might consume 20mA (0.02A) per bulb, while a SMD (surface-mounted) LED can draw 60mA or more. High-lumen LEDs (e.g., 100+ lumens) are brighter but consume more power. For instance:

• Standard 5mm LED (20 lumens): 20mA per LED
• High-output SMD LED (120 lumens): 60mA per LED

A string with 100 high-output SMD LEDs could draw up to 6 amps at the LED level, but after voltage conversion, the wall-plug draw might still be under 0.5 amps. This is why efficiency matters—look for LEDs with high lumens-per-watt ratings (e.g., 80–100 lm/W).

Color and Color Temperature

White LEDs (especially cool white, 5000K+) tend to be more efficient than colored LEDs. Red LEDs, for example, often require less voltage (1.8–2.2V) compared to blue or white (3.0–3.6V), but this doesn’t always translate to lower amperage because the driver adjusts the current. RGB (color-changing) LEDs use multiple chips and can draw more power when multiple colors are lit simultaneously. A single RGB LED might draw 60mA when white (all colors on), but only 20mA when red-only.

How to Calculate LED String Light Amperage

Step-by-Step Calculation Using Wattage and Voltage

The simplest way to estimate amperage is using the formula: Amps = Watts ÷ Volts. Here’s how to apply it:

1. Find the wattage: Check the product label or manual. A typical LED string might use 4.8 watts for 100 LEDs.
2. Identify the voltage: Most are 120V AC (US) or 230V AC (EU).
3. Calculate amps: For a 4.8W, 120V string: 4.8 ÷ 120 = 0.04 amps.

For example, a 50-foot string with 200 LEDs might use 9.6 watts (0.048 amps per 100 LEDs × 2). Total amps = 9.6W ÷ 120V = 0.08 amps.

Using Manufacturer Specifications

Many manufacturers list amperage directly on the packaging or in the manual. Look for:

• “Input current: 0.2A”
• “Max load: 15A” (for end-to-end connections)
• “UL Listed” or “ETL Certified” (ensures safety testing)

If amperage isn’t listed, check for wattage and voltage, then use the formula above. For RGB or smart LED strings (e.g., Wi-Fi-controlled), check if the controller adds extra power draw (typically 0.5–1 watt).

Real-World Example: Holiday Light Setup

Suppose you’re decorating your house with 10 LED string lights:

• Each string: 50 feet, 200 LEDs, 9.6 watts
• Total wattage: 10 × 9.6 = 96 watts
• Total amps: 96W ÷ 120V = 0.8 amps

This is well within the 15-amp limit of a standard circuit (which can handle up to 1,800 watts). However, if you’re also running a space heater (1,500W = 12.5A), the total draw (13.3A) approaches the limit—best to use separate circuits.

Comparing LED vs. Incandescent String Lights

Amperage Differences Between LED and Incandescent

LED string lights are significantly more efficient. Here’s a comparison for 100-foot strands:

• LED (200 LEDs): 9.6W, 0.08A at 120V
• Incandescent (200 mini bulbs): 40W, 0.33A at 120V

That’s a 76% reduction in amperage for the same length and light output. Over 10 strands, LEDs draw 0.8A, while incandescents draw 3.3A—a huge difference when managing circuits.

Heat Output and Safety

Incandescent bulbs waste 90% of energy as heat. A 40W incandescent string can get hot enough to damage insulation or start fires if wrapped around flammable materials. LEDs, by contrast, stay cool to the touch. This lower heat output means:

• Safer for indoor/outdoor use
• Less strain on extension cords and power strips
• Lower risk of circuit overheating

Long-Term Cost Savings

While LED strings may cost more upfront (e.g., $15–25 vs. $5–10 for incandescent), they last 25,000–50,000 hours (vs. 1,000–2,000 hours for incandescents). The energy savings add up:

• 10 LED strings (96W): $1.15/month (12h/day, $0.12/kWh)
• 10 incandescent strings (400W): $5.76/month

Over 5 years, LEDs save over $270 in electricity alone.

Safe Usage and Circuit Management

How Many LED Strings Can You Plug In?

Standard household circuits are rated for 15 or 20 amps (1,800–2,400 watts at 120V). To avoid overloads:

• 15-amp circuit: Max 180 watts (15A × 120V × 0.8 safety factor)
• 20-amp circuit: Max 240 watts

For LED strings (e.g., 9.6W each):

• 15A circuit: Up to 18 strings (172.8W total)
• 20A circuit: Up to 25 strings (240W total)

But never exceed the end-to-end connection limit (often 2–3 strings max) to avoid voltage drop and overheating at the connectors.

Extension Cords and Power Strips

Use heavy-duty extension cords (14-gauge or thicker) for long runs or high loads. Avoid daisy-chaining power strips—this can cause overheating. Instead:

• Use a single power strip with a built-in circuit breaker (e.g., 15A)
• Distribute loads across multiple outlets on different circuits
• Check for UL/ETL certification on all accessories

Outdoor and Wet Location Safety

For outdoor use, ensure LED strings are rated “Wet Location” or “IP65” (dust/water-resistant). Use outdoor-rated extension cords and GFCI (Ground Fault Circuit Interrupter) outlets to prevent shocks. Never bury cords or run them under rugs.

Advanced LED Lighting: Smart and RGB Options

Smart LED Strings and Controllers

Wi-Fi or Bluetooth-enabled LED strings (e.g., Philips Hue, Nanoleaf) include small controllers that add minimal power draw (0.5–1W). These allow:

• Color changes (RGB)
• Brightness dimming
• Scheduling and remote control

Amperage impact: A 10W smart string (9.5W LEDs + 0.5W controller) draws 0.083A at 120V—almost identical to a standard LED string.

RGB and Addressable LED Strips

RGB strings use three LEDs (red, green, blue) per node, so power draw increases when multiple colors are lit. Addressable LEDs (e.g., WS2812B) allow individual control but draw more power (e.g., 0.06A per LED at full white vs. 0.02A for single-color). A 300-LED addressable strip can draw up to 18A at the LED level, but the wall-plug draw depends on the power supply:

• 12V, 18A power supply: 216W total, 1.8A at 120V input

Always use a power supply with 20% overhead (e.g., 250W for a 200W load).

Dimming and Energy-Saving Modes

Many LED strings include dimming or “eco” modes that reduce brightness and power draw. For example:

• Full brightness: 0.08A
• 50% brightness: 0.04A (50% energy savings)

Use these modes for ambient lighting to extend battery life (for battery-powered strings) or reduce circuit load.

Data Table: LED String Light Amperage Reference

LED Type	Length (ft)	LEDs per String	Wattage	Voltage	Amps (Input)	Notes
Standard White	25	100	4.8W	120V AC	0.04A	5mm LEDs, 20 lumens/LED
High-Density White	50	200	9.6W	120V AC	0.08A	SMD LEDs, 100 lumens/LED
RGB Color-Changing	50	200	12W	120V AC	0.10A	All colors on, controller included
12V Low-Voltage	100	200	24W	12V DC (120V AC input)	0.20A	Outdoor landscape lighting
USB-Powered	16	50	5W	5V DC	1.00A	USB port draw; negligible wall draw
Incandescent (Comparison)	100	200	40W	120V AC	0.33A	Mini bulbs, 5 lumens/bulb

Conclusion

Understanding how many amps a string of LED lights uses is essential for safe, efficient, and cost-effective lighting. On average, a standard 50-foot LED string draws between 0.08 and 0.2 amps at 120V, making them far more efficient than incandescent alternatives. Key takeaways:

• Calculate amperage using: Amps = Watts ÷ Volts.
• Respect circuit limits: Stay under 15–20 amps per circuit (1,800–2,400W).
• Check manufacturer specs for wattage, voltage, and connection limits.
• Choose LED over incandescent for lower amperage, heat, and long-term costs.
• Use smart features wisely: RGB and controllers add minimal draw but offer flexibility.

By following these guidelines, you can illuminate your home, garden, or event space with confidence—without overloading circuits or risking safety. Whether you’re hanging holiday lights or installing permanent LED strips, knowing the amperage ensures your setup is as efficient as it is beautiful.

Frequently Asked Questions

How many amps does a string of LED lights use for indoor decor?

A typical string of LED lights uses 0.05 to 0.2 amps, depending on length and bulb count. Always check the manufacturer’s specifications for the exact amp draw of your model.

Can I plug multiple LED light strings into the same outlet without overloading it?

Yes, most outlets handle 15–20 amps, so you can safely connect multiple LED strings (e.g., 10–20 strings at 0.1 amps each). Use a power strip with overload protection for added safety.

How many amps does a string of LED lights use compared to incandescent bulbs?

LED lights use up to 90% fewer amps than incandescent bulbs. For example, a 100-bulb incandescent string may draw 4 amps, while an equivalent LED string uses just 0.1 amps.

Do outdoor LED light strings use more amps than indoor ones?

Not necessarily—amp usage depends on bulb count and design, not location. However, outdoor-rated LED strings may have slightly higher draw due to weatherproofing features.

How can I calculate the amp usage of my specific LED light string?

Check the product label or manual for wattage, then divide by voltage (e.g., 20W ÷ 120V = 0.17 amps). For accuracy, use a plug-in amp meter to measure actual draw.

Is it safe to use LED light strings on a dimmer switch?

Only if the lights are labeled “dimmable.” Non-dimmable LEDs may draw inconsistent amps, causing flickering or damage. Always verify compatibility before connecting to a dimmer.