Choosing the right power supply is one of the most critical (and most overlooked) steps in any LED strip project. Use the wrong power supply, and you'll face dim lighting, flickering, or premature failure.

As an experienced LED strip light manufacturer, Arraystar LED sees this problem every day. This guide will help you calculate wattage and choose the perfect power supply for your project.

Why Power Supply Matters

LED strips run on low voltage (usually 12V or 24V DC). The power supply converts mains AC voltage (110V/220V) to the low-voltage DC your strips need.

Problems with the wrong power supply:

• Undersized (too low wattage): Dim lighting, flickering, overheating

• Oversized (too high wattage): Wasted money, slightly less efficient

• Wrong voltage: Instant destruction of your LED strip

• Poor quality: Short lifespan, flickering, unreliable

Step 1: Determine Your LED Strip Wattage

Check the specifications of your LED strip for watts per meter (W/m).

Common LED Strip Wattages:

• SMD 2835 (60 LEDs/m): 4.8W/m

• SMD 2835 (120 LEDs/m): 9.6W/m

• SMD 5050 (30 LEDs/m): 7.2W/m

• SMD 5050 (60 LEDs/m): 14.4W/m

• COB LED Strip: 10-20W/m

• LED Neon Flex: 10-18W/m

Example: 5 meters of SMD 5050 (14.4W/m) = 72W total

Step 2: Add a Safety Buffer

Always add 20% extra wattage to your calculation. This is critical because:

• LED strips can pull slightly more power at startup

• Voltage drop reduces effective brightness

• Power supplies run cooler and last longer when not at max capacity

Formula:

Total wattage = (LED strip wattage per meter × total length) × 1.2

Example:

• 5m × 14.4W/m = 72W

• 72W × 1.2 = 86.4W

• Choose a 100W power supply (next standard size up)

Step 3: Choose the Right Voltage

LED strips come in 12V or 24V versions. Make sure your power supply matches!

12V LED Strips:

• Better for shorter runs (up to 5m)

• More common, widely available

• Lower voltage = thicker wires needed

24V LED Strips:

• Better for longer runs (up to 10m+)

• Less voltage drop

• More efficient for high-power strips

• Often used for COB and high-density strips

Important: Never mix voltages! 12V strip + 24V power supply = destroyed LEDs.

Step 4: Choose the Right Power Supply Type

Indoor Power Supplies:

• Desktop/Plug-in — simple, plug into wall outlet

• Built-in/Internal — hidden in cabinets or fixtures

• Dimmable — compatible with LED dimmers (triac, 0-10V, etc.)

Outdoor Power Supplies:

• IP65+ rated — weatherproof, for outdoor use

• Junction box style — heavy-duty, protects from elements

• Rigid metal housing — better durability

Step 5: Account for Voltage Drop

Voltage drop happens over long wire runs, causing dimmer lighting at the far end.

Solutions for long runs:

1. Use 24V instead of 12V — less voltage drop

2. Use thicker wires — lower resistance = less drop

3. Power from both ends — inject power at both ends of the strip

4. Split into multiple runs — don't exceed 5m (12V) or 10m (24V)

Power Supply Sizing Cheat Sheet

• 1m (14.4W/m strip): 17W → 20W or 30W supply

• 2m: 35W → 40W or 50W supply

• 3m: 52W → 60W supply

• 5m: 86W → 100W supply

• 10m (24V): 173W → 200W supply

Note: If using multiple strips, add them all up and use one big power supply or multiple smaller ones.

Common Mistakes to Avoid

1. Forgetting the 20% buffer — this causes overheating and short lifespan

2. Using indoor supply outdoors — moisture destroys unrated supplies

3. Daisy-chaining too many strips — split between multiple power supplies

4. Ignoring voltage drop — dim lights at the end of long runs

5. Cheap no-name power supplies — save money on strips, not power supplies

Quality Matters: Choose a Good Power Supply

A cheap power supply can damage your expensive LED strips. Look for:

• Certified brands — UL, CE, RoHS certified

• Over-voltage protection — protects your strips

• Over-current protection — shuts down on faults

• Good thermal design — runs cooler, lasts longer

• 2+ year warranty — quality manufacturers stand behind their products

Get Quality LED Strips & Power Supplies

At Arraystar LED, we supply complete LED strip lighting solutions:

• LED strips — COB, SMD, neon flex (12V / 24V)

• Power supplies — indoor/outdoor, various wattages

• Controllers & dimmers — WiFi, Bluetooth, RF control

• Accessories — connectors, aluminum channels, mounting clips

📧 Email: info@arraystarled.com
📱 WhatsApp: +86 158 1851 4077
🌐 Website: www.arraystarled.com

Tell us your project, and we'll recommend the right LED strip and power supply combination.