What Size Grow Light Do I Need?(LED & HID Lights)

When people ready to use LED grow lights,they may want to find these answer:

What light is best for plant growing?

What size grow light do i need?

How many watts do i need? etc

There are so many questions and make them feel confused.We will explore the answer-What size grow light do i need in this guide.Let’s look at these detail.

What Size LED Grow Light Do I Need

In fact,if we want to know what size grow light do i need ,it will get a bit complicated.The size of grow light depends on a variety of different factors,such as:the type of grow light, the plant you will grow, the area of your plant, etc.

No matter what we will give it as simple as possible.In order to archive the best yield, we recommend that choose LED growth lights to meet at least 40w per square foot.

Grow light is the most important equipment in the growing Light just like plant food, we provide high-quality “food” for plants so that they can produce high-quality yields. LED grow lights are considered to be the best lighting option due to its good energy efficiency, durability and full spectrum etc.

However, even if you know it is a good solution to choose LED grow light and related technical terms, finding the right grow lights for your planting is still a overwhelming.

To determine what size LED grow light is needed, you first need to calculate the actual size of your growing area.

The size of the growing area

When growing X plant, at least 50 watts of LED plant lights per square foot.Therefore, we need to calculate the square feet (length x width).Then, this number by 50w to get the rough wattage of the grow light we need.

For example: a growing area that is 2 feet long and 3 feet wide. Square feet is 6 (2ft x 3ft), this number by 50w to get 300wats. Hence, I need a power of LED grow light not less 300w.

How many plants can be grown?

In general, each X plant requires at least 1 square foot,After sprouting, many growers like to put plant in a tent with area about 1 square foot.This tent allows plants to grow big and strong without being obstructed by other plants or around the tent.

Make sure canopy cover

Most LED plant grow lights usually only cover about 1-6 plants.

If you want to plant more, you need to buy multiple lights hanging side by side to cover each plant to get enough light.

The following table lists how watts you need with the size of your growing area, and how many plants for each size of growth light.

Growing areaMin PowerQuantity(X Plants)
2 sq ft(2*1)100W1-2 plants
4 sq ft(2*2)200W1-3 plants
6 sq ft(2*3)300W1-6 plants
9 sq ft(3*3)450W1-9 plants
12 sq ft(3*4)600W1-12 plants
16 sq ft(4*4)800W1-16 plants
20 sq ft(4*5)1000W1-20 plants

Note: 1 square foot of growing area = 50 watts of LED plant growth lights

The above are reference values during flowering. You can reduce the power during the nursery and growth period,

This plant led grow light adopts 2835 lamp beads,it has the advantages of stable performance, high brightness, high efficiency, impact resistance, strong shock resistance.180-degree adjustable angle installation is suitable for indoor garden or indoor potted landscape.

PAR output

PAR is a part of the spectral parameters used by plants for photosynthesis.The higher the PAR output of the plant light, the more light the plant get.

The following table is the best PAR range of each stage of the X plant:

Growing StagePAR

It is recommend choose the output PAR of LED grow lights within the above range.

What Size HPS and Metal Halide Grow Light Do I Need

In addition to LED grow light,HPS light and metal halide light are widely used as grow lights.So,how to choose the size of  HPS and metal halide light?

By Wattage

One is know what size HPS and metal halide grow light do I need is based on plant wattage requirement per square foot of canopy.For high light requirement plant, like tomato, you should 30 to 50 watts per square foot of canopy.

We can choose the middle value 40 watts per square foot. If you have enough budget,you also can choose 50 watts per square foot.

For example, Suppose you have a growing area that is 20 by 40 feet, or 800 square feet.

To meet 40 watts per square foot, we need a total of 32,000 watts to cover this growing area (800 x 40 = 32,000).

You will need 53 or 54 piece of 600W light(32,000/600=53.3) or 32 piece of 1000 watt light (32,000 / 1000 = 32).

This LED Plant light adopts super shape with high lumen output. three aluminum LED heads are adjustable. They are can be folded up to 90°,this will make the light cover a wide area.It is suitable for indoor plant growth.

By Coverage Area

If you know the size of your growing tent or growing area, you can easily know how many watts do i need by coverage area. The following are the most common watts for HPS and metal halide light:

150 watt: 2 x 2 feet (or 4 square feet)

250 watt: 2.5 x 2.5 feet (or 6.25 square feet)

400 watt: 3 x 3 feet (or 95 square feet)

600 watt: 4 x 4 feet (or 16 square feet)

1000 watt: 5 x 5 feet (or 25 square feet)

From above, you should easily know how many watts you need.Other things being equal,if you prefer to choose 600 watt lights,you will get more output per watt of electricity used,in other word,it is the most efficient and 1000 watt bulbs are second best, so we should prefer to choose 600 watt or 1000 watt light.

For example, Suppose you have a growing area that is 20 by 40 feet, or 800 square feet.

You could light the growing area with 50 piece of 600 watts each (800/16=50) or with 32 piece of 1000 watts each (800/25=32).

In this case though, I would choose 1000 watt option, since 32 of them perfectly cover the area.

But the result is based on the maximum coverage areas for each light strength.That means the number of lights are closer to the minimum light requirement for plants growing requirements.

LED growth light size for tent

Expert advice you should meet for 30-50 watts per square foot of grow area for most of plant,and 30 watts per 1 sq for medium light plant and 50 watts per 1 sq for high light plant.So,we can easily to calculate these size of grow light.

What Size Led Light For 1×1 Grow Tent

You’ll need around 30-50 watts of light power for a 1×1 grow tent.So, you’ll need a 30-50 watts light source for your 1×1 grow tent.

What Size Led Light For 2x2 Grow Tent

You’ll need around 120-200 watts of light power for a 2×2 grow tent.So, you’ll need a 100 or 200 watts light source for your 2×2 grow tent.

What Size Led Light For 2x4 Grow Tent

You’ll need around 240-4000 watts of light power for a 2×4 grow tent.So, you’ll need a 200- 400 watts light source for your 2×4 grow tent.

What Size Led Light For 3x3 Grow Tent

You’ll need around 270-450 watts of light power for a 3×3 grow tent.So, you’ll need a 200- 400 watts light source for your 3×3 grow tent.

What Size Led Light For 4x4 Grow Tent

You’ll need around 480-80 watts of light power for a 4×4 grow tent.So, you’ll need a 400- 800 watts light source for your 4×4 grow tent.

What Size Led Light For 4x8 Grow Tent

You’ll need around 960-1600 watts of light power for a 4×8 grow tent.So, you’ll need a 800- 1000 watts light source for your 4×8 grow tent or two piece of 600-800 watts LED lights for 4×8 grow tent.

What Size Led Light For 5x5 Grow Tent

You’ll need around 750-1250 watts of light power for a 5×85 grow tent.So, you’ll need a 700- 1000 watts light source for your 5×5 grow tent or two piece of 600 watts LED lights for 5×5 grow tent.

Quantum LED Grow Light

This quantum grow light adopts high brightness LED chip,it is suitable for all indoor growing environment: grow tent, grow room; best for growth and bloom stage.

Wrapping Up

In this article we explore how to choose the size of growing light,Before determining the size you first know the size of the growing area,the type of grow light and how many watts per square meter you need,After that,it is not difficult to choose right LED grow light.