How many amps does an LED strip draw?

An LED strip's current draw is its total wattage divided by its supply voltage, and the wattage depends on LED density, the type of LED and the length of the run. As a worked example, 5 metres of 60 LED/m WS2812b at 5 V draws about 33.9 W, or 6.8 A, at full white. The Lightstrip Calculator derives this from the measured consumption of a full reel, divided across its LEDs and multiplied by the LEDs in your run, using Quindor's Real World Powersheet — which measures actual draw rather than the optimistic figures printed on the packaging.

What is power injection and how many injection points do I need?

Power injection means feeding power into an LED strip at more than one point along its length, rather than only at one end, so the far end is not dimmer than the near end. A single injection point can carry roughly 4.26 A before the solder joint and the strip's copper traces become the limiting factor. Below that you can feed the strip from one end. Up to twice that, feed both ends. Beyond that you need additional injection points spaced along the middle of the run, and the calculator works out how many.

What size power supply do I need for my LED strip?

Size the supply for the calculated current plus 20% headroom, so it is not running at its limit continuously. The calculator applies that margin and then picks the smallest catalogued supply that covers it.

What wire gauge should I use for LED strips?

Thick enough that the voltage drop over the round trip stays under 10%. That depends on the current through that particular run, the supply voltage and the cable length, so a short 5 V run and a long 24 V run need very different wire. The calculator has an AWG calculator for each injection point.

What is the difference between RGB, RGBW and analog LED strips?

Digital RGB strips address each LED or zone individually, which is what makes animations and gradients possible. Digital RGBW adds a dedicated white diode for better-quality white light where you need to actually see what you are doing. Analog strips drive every LED from the same signal, so no effects, but they are cheaper, brighter per euro, and often available with CRI 90+ white diodes.

Where can I cut an LED strip?

Only at the marked cut points, which fall at fixed intervals set by how many LEDs share a zone. A run is therefore rounded down to the nearest cut point, so the usable length is often slightly shorter than the space you measured. The calculator reports the actual length after cutting rather than the length you asked for.

Can I use this calculator in feet instead of metres?

The Lightstrip Calculator works in both metres and feet — use the unit toggle beside the length field to switch. Lengths are shown and entered in the chosen unit, though LED density stays as LEDs per metre, because that is how strips are specified and sold.

Lightstrip Calculator

Whether you are new to installing lightstrips or a seasoned professional, finding the correct lightstrip, calculating the power requirements, and gathering all the necessary items for your specific use case can be a daunting task.

This calculator aims to simplify the process and get you started as quickly as possible. Enter the length of your run and the calculator works out the voltage and current, how many power injection points you need, the wire gauge for each, and a full bill of materials.

Choosing the right lightstrip

Which strip suits a job depends on what the light is for. The three purposes below map onto genuinely different hardware, and picking the wrong one is the most common reason a finished install disappoints.

Digital RGB, digital RGBW and analog LED strips compared
	RGB	RGBW	Analog
Addressable	Every LED individually	In zones	No — one signal drives the whole strip
White light	Mixed from red, green and blue — tinted, low CRI	Dedicated white diode — clean, usable white	Dedicated white diodes, CRI 90+ commonly available
Effects	Yes — animations, gradients, chases	Yes — zones and patterns	No
Voltages available	5 V or 12 V	12 V or 24 V	24 V
Best for	Decorative and mood lighting	Task and accent lighting you work under	Primary room lighting

Ambient Lighting (Digital RGB)

Primary use: Dynamic ambient lighting and decorative effects.

Digital RGB allows for colorful animations, gradients, and patterns, making it perfect for creating mood lighting in spaces like gaming setups, media rooms, or behind TVs.

Bias lighting behind screens
Gaming and entertainment setups
Decorative lighting with dynamic effects

Task-oriented accent lighting (Digital RGBW)

Primary use: Task-oriented accent lighting where individual control of LEDs is needed and pure white light is desirable.

RGBW adds a dedicated white LED (W), which provides better-quality white light for functional purposes, such as under-cabinet lighting or stair lighting. Digital control allows creating zones or patterns for more customized and visually interesting effects.

Under-cabinet lighting (kitchen workspaces, bars)
Staircase lighting (dynamic effects or zones)
Pathway lighting with individual LED control

Primary Lighting (Analog)

Primary use: Primary/general illumination (ceiling, walls) or basic accent lighting where uniform lighting is needed.

Analog strips offer consistent, broad illumination at a lower cost. Since all LEDs share the same control signal, it's not designed for dynamic effects but excels in providing uniform and bright light, which is ideal for primary lighting.

Additionally, analog strips often feature high-quality white diodes capable of achieving a Color Rendering Index (CRI) score of 90+, meaning they render colors more accurately and vividly, making them a great choice for spaces where natural and precise color representation is important.

Ceiling lighting (general illumination in living rooms, offices)
Wall lighting or coves
Accent lighting for simple, uniform effects

How the calculator works

Select the purpose of the lightstrip. Choose whether you are lighting for ambience, for task and accent work, or as the primary light source for a room. The purpose determines whether you want digital RGB, digital RGBW or analog strips, and the calculator only offers strips suited to it.
Enter the available length. Enter the length of the run you need, in metres or feet. The calculator works out how that maps onto the strip's cut zones, since a strip can only be cut at fixed intervals and the usable length is rounded down to the nearest cut point.
Read the results and bill of materials. Each matching strip expands to show its power draw in watts and amps, the number of power injection points needed, and a full bill of materials: controller, power supply, wire gauge, aluminium diffuser and tools.

Reading your results

Each matching strip is a section you can expand. Inside, the information is grouped as follows.

Calculations: The voltage and current the run requires, and the length it will actually be once cut to the nearest cut point. This is the figure to size everything else against.
Bill of materials: Every part the setup needs: the WLED controller suited to the current, a power supply with headroom, the wire gauge for each injection point, an aluminium diffuser, and the crimping tools worth having. Each item links to a vendor.
Expandable detail: The injection and wire gauge sections expand to show how the numbers were reached, including a calculator for the specific cable run you are wiring.

Before you buy

Double-check the calculations to avoid underpowering or overpowering the lightstrip.
Use quality components from reputable sources — a cheap supply is the usual cause of flicker.
Refer to the manufacturer manuals for additional setup guidance.
Test the setup before final installation, while everything is still reachable.

How the numbers are calculated

Power comes from the measured draw of a full reel, divided across its LEDs and multiplied by the LEDs in your run:

watts per LED = reel watts ÷ (LEDs per metre × reel length)
total watts   = total LEDs × watts per LED
amps          = total watts ÷ voltage

From there: a single power injection point carries about 4.26 A before the strip's copper traces limit it, and the power supply is sized for the calculated current plus 20% headroom.

Reel wattages are measured rather than taken from packaging. Source: Quindor's Real World Powersheet and quinled.info on strip wiring.

Every formula in full, including cut points and voltage drop, or the parts and wire gauge chart.

Frequently asked questions

How many amps does an LED strip draw?: An LED strip's current draw is its total wattage divided by its supply voltage, and the wattage depends on LED density, the type of LED and the length of the run. As a worked example, 5 metres of 60 LED/m WS2812b at 5 V draws about 33.9 W, or 6.8 A, at full white. The Lightstrip Calculator derives this from the measured consumption of a full reel, divided across its LEDs and multiplied by the LEDs in your run, using Quindor's Real World Powersheet — which measures actual draw rather than the optimistic figures printed on the packaging.
What is power injection and how many injection points do I need?: Power injection means feeding power into an LED strip at more than one point along its length, rather than only at one end, so the far end is not dimmer than the near end. A single injection point can carry roughly 4.26 A before the solder joint and the strip's copper traces become the limiting factor. Below that you can feed the strip from one end. Up to twice that, feed both ends. Beyond that you need additional injection points spaced along the middle of the run, and the calculator works out how many.
What size power supply do I need for my LED strip?: Size the supply for the calculated current plus 20% headroom, so it is not running at its limit continuously. The calculator applies that margin and then picks the smallest catalogued supply that covers it.
What wire gauge should I use for LED strips?: Thick enough that the voltage drop over the round trip stays under 10%. That depends on the current through that particular run, the supply voltage and the cable length, so a short 5 V run and a long 24 V run need very different wire. The calculator has an AWG calculator for each injection point.
What is the difference between RGB, RGBW and analog LED strips?: Digital RGB strips address each LED or zone individually, which is what makes animations and gradients possible. Digital RGBW adds a dedicated white diode for better-quality white light where you need to actually see what you are doing. Analog strips drive every LED from the same signal, so no effects, but they are cheaper, brighter per euro, and often available with CRI 90+ white diodes.
Where can I cut an LED strip?: Only at the marked cut points, which fall at fixed intervals set by how many LEDs share a zone. A run is therefore rounded down to the nearest cut point, so the usable length is often slightly shorter than the space you measured. The calculator reports the actual length after cutting rather than the length you asked for.
Can I use this calculator in feet instead of metres?: The Lightstrip Calculator works in both metres and feet — use the unit toggle beside the length field to switch. Lengths are shown and entered in the chosen unit, though LED density stays as LEDs per metre, because that is how strips are specified and sold.

Calculators by lightstrip type

RGB LED Strip Calculator — Work out the power, injection points and wiring for a digital RGB LED strip run, and get a full bill of materials.
RGBW LED Strip Calculator — Size the power supply, injection points and wire gauge for a digital RGBW LED strip, with a full bill of materials.
Analog LED Strip Calculator — Calculate power draw, injection points and wiring for analog (non-addressable) LED strips used as primary room lighting.

Reference

How LED Strip Power Is Calculated — The formulas behind LED strip power: current draw, cut points, power injection, supply sizing and voltage drop, with worked sources.
LED Strip Wiring, Wire Gauge and Parts — What an LED strip setup needs — controller, power supply, wiring and diffuser — plus an AWG wire gauge chart with areas and conductor diameters.