How Many LED Lights Do I Need for My Grow Room? How to Calculate Your LED Lighting Needs (2023)

FAQs

How do you calculate how many LED lights do I need? ›

To determine the needed lumens, you will need to multiply your room square footage by your room foot-candle requirement. For example, a 100 square foot living room, which needs 10-20 foot-candles, will need 1,000-2,000 lumens. A 100 square foot dining room, which needs 30-40 foot-candles, will need 3,000-4,000 lumens.

Let's say you are growing in a 5' x 5' grow space. If your plants need 20-30 watts/square foot, and your canopy takes up 4' x 4' of that space, you will need 320-480 watts of grow lighting.

As a rule of thumb, aim for 20 to 40 watts per square foot.

For the average space of 250 square feet, you'll need roughly 5,000 lumens as your primary light source (20 lumens x 250 square feet).

Let's recap how to gauge how much light you need for a space. Multiply your room square footage by the footcandle requirement. For example, a 100-square foot living room, which needs 20 foot candles, will need 2,000 lumens. A 100-square foot dining room, which needs 40 foot-candles, will need 4,000 lumens.

This HPS and MH grow light kit will provide the necessary lumens to up to 6 plants in a 5x5 grow tent through the vegging and flowering stages. The power of this 1000w light is perfect for providing the coverage and depth to reach all of your plants.

Lower wattage LEDs of around 200 watts should sit between 12-20 inches from the top of the plant. Higher wattage LEDs of 1000 watts and above should sit between 36-46 inches from the top of the plant.

For example, one single 300W LED light fixture may be fine for one or maybe two plants, but it may not be enough to cover a bigger space with multiple plants. So make sure to reference any recommendations from the vendor and/or LED manufacturer on how much light you will need for your growing space.

Can too much LED light hurt plants? ›

Intense, direct light is great for some plants, but it will damage (or even kill others). The plant isn't able to convert all of the light into consumable energy, and the excess creates a heat issue over time. The plant might use available water to cool itself, which creates a moisture shortage as well.

For established plants, they are already where they need to be in order to thrive. During the flowering stage LED Grow lights should be located between 16-36 inches from the plant canopy. Moving the grow light closer will increase the light intensity which can maximize photosynthesis.

2 month plants should give about 40g per plant, so with about 9 you'll be able to easily fill a square meter and get up to 400g per 600w light. 3 month autoflowering plants grow much bigger, however, so you should only plant 4 per 600w light.

To be effective, grow lights really need to be on for at least 8-10 hours a day. This can vary up to 16 hours, depending on the conditions. That's why LED grow lights are so popular – when they have to be left on all day, it's best to use an energy efficient type!

A good rule-of-thumb for LED grow lights is 32 watts of actual wattage per square foot of growing space for flowering medical or other large flowering plants.

As a handy rule of thumb, a sitting room or bedroom will generally require around 10-20 lumens per square foot, while a bathroom or kitchen will need a stronger level of lighting, at around 70-80 lumens per square foot. To work out the lumens you need, simply multiply the square footage of the room by this figure.

A 1000 lumen flashlight is quite bright and, depending on the lens or reflector design, powerful enough to reach a distance of 200 meters or more. This type of flashlight allows you to see objects from a far distance.

Light Brightness and Lumens

Vegetable seedlings and other “full sun” plants require about 2000 to 3000 lumens (at minimum) per square foot of growing space. So, if you're growing just a single standard tray of seedlings, using a grow light that emits 3000 lumens is sufficient.

A level between 4,000 and 8,000 lumens is ideal. This is a wide spread so you can choose the amount that is right for your bathroom size.

A 5000-lumen LED bulb is a very bright light source, and if you are using it in a relatively small room, it can be very harsh. In this case, it is recommended that you use a 1000-lumen LED bulb. Under normal circumstances, garages, utility rooms, and warehouses are more suitable for 5000-lumen bulbs.

WHAT LED bulb equals 60 watts? ›

A 60-watt incandescent light bulb can be replaced with a 10-watt LED.

The watt per square meter method is fundamentally a rule of thumb method. This method of lighting calculation comes in handy when doing a quick calculation or double-check.

This rule states that an OCPD can be loaded to only 80% of its rating for continuous loads. Remember that 80% is the inverse of 125% (0.80 = 1 ÷ 1.25) and, as such, the rules are indeed identical in their end requirement.

Since the lighting ratio is the ratio of the light levels on the brightest lit to the least lit parts of the subject, and the brightest lit are lit by both key (K) and fill (F), therefore the lighting ratio is properly (K+F):F although for contrast ratios of 4:1 or more, then K:F is sufficiently accurate.

As can be seen from the guide, 300 watt LED is the best replacement for your 1000 Watt Metal Halide.

Large Plants

These lights range in power from 100 to 1000 watts. The 400 and 1000 watt lights are the most useful. A 1000 watt grow light can light up an area of about 7 feet square when the light is suspended 2 feet above the plants. A 400 watt light would work for an area of about 4 feet square.

You need to divide your wattage by 1,000 (1,000 kilowats in 1 watt). So, if we were to run a 1000 watt grow light 18 hours a day with the kWh rate we gave earlier, our formula would be: 1 x $0.1559 x 18 x 30 = $84.186/month. $120.00 on sale until 12/24/2022! $250.00 on sale until 12/24/2022!

Telltale Signs of Too Much Light

The most apparent sign is leaf burning. This typically causes the yellowing of leaves at the top of the plant but the veins stay green, and the leaves take on a yellow or brown, burnt look.

Electrical Safety for the Indoor Growrooms

A 1000w HPS or Metal Halide light takes 9 amps at 120 volts so you can only run one on a wall outlet circuit. A standard dryer outlet is 220 volts and 30 amps so you can power up to six 1000 watt lights on that circuit.

How far should 100w LED grow lights be from plants? ›

According to our current data, the average wattage required per square foot is 32 watts (although this also depends on the plant, so we are taking averages here), so a 4×4 tent theoretically requires 512 watts for complete coverage. This number can float between 500 watts and 600 watts.

How Far Should LED Grow Lights Be From Seedlings? Seedlings are delicate and should be started at the maximum recommended distance away from the LED grow light. A safe distance for all of the G8LED grow lights is 12-36 inches above seedlings to start, depending on the size of the light.

While LED lights do produce some heat, they deal with that heat more effectively than other light types. Plants can grow much closer to LEDs than other lighting types because of this. Usually crops can grow right up to the light without burning.

Green light is the least effective for plants because they are themselves green due to the pigment Chlorophyll. Different color light helps plants achieve different goals as well.

Offering low energy usage, low heat, and color optimized for growth, LED lights are the most efficient, effective, and customer-friendly way to grow plants at home than growing with fluorescent lights or incandescent lights.

Light Intensity and Yields

The light intensity rule of thumb is that a 1% increase in light equals to a 1% percent increase in yield. In a study by Wageninen University, they discovered this to be true of all horticultural crops they evaluated including, fruiting (vine) crops and flowers.

But, there's a reason why some of the largest commercial grow operations have made the switch to LED. A 600w HPS light can produce up to 150 to 300 grams in optimal growing environments, which is 0.5 grams per watt or less. LEDs, however, can produce as high as 1 to 1.5 grams per watt.

LEDs have much higher efficacy than HPS lights. LEDs are much more efficient than HPS lamps, which allows them to use lesser watts to achieve the same or higher output. The VOLT Grow® 720W FL-1 light produces a higher light output than a standard 1000W HPS light while using 30% less power.

Faster flowering can result in significant savings and better profitability for plant breeders. Various conditions can affect the flowering speed, but the quality of the light spectrum is probably the most important.

Can I leave LED grow lights on all night? ›

A: In general, you should not leave grow lights on 24/7. Plants need a light-dark cycle to develop properly. It's believed that they truly do “rest” during periods of darkness, and probably use this time to move nutrients into their extremities while taking a break from growing.

The LED grow lights should be between 12-24 inches from the top foliage of your marijuana canopy. Monitor the plants closely to make sure they have enough light and not too much, which can cause adverse effects such as bleaching, discoloration, stunted or irregular growth.

To give you an idea, leafy plants need around a PAR of 200, while fruit-bearing plants would thrive between 400 – 500, depending on the plant. Knowing how much PAR a grow light has will affect how a plant grows. If the PAR is too low, your plant will have a hard time growing and will likely have stunted growth.

You have a 12 V supply and each LED might need up to 3.5 V. (12 V)/(3.5 V) = 3.4 LEDs max. Since you can only have whole LEDs, the answer is 3.

Multiply width of room x length of room x 1.5 = amount of total minimum wattage needed (assuming an eight foot ceiling). Divide by 60 to get the number of 60-watt equivalent bulbs required. Then, add up the wattage in each bulb in each fixture to figure out how many light fixtures are needed.

Number of Lights

To calculate the current draw for each fixture, divide its wattage by 110 volts. For example, a 100-watt fixture would draw 100 divided by 110, or approximately 0.9 ampere. For 100-watt fixtures, you can have a maximum of 12 divided by 0.9A, or 13 fixtures.

“A good rule of thumb is 100 lights for every foot-and-a-half of tree,” according to Lowe's. But Better Homes & Gardens recommends using three 100-light sets for every foot of a tree's height. And Real Simple suggests 100 lights for every foot.

LED lights require a certain voltage, such as 24 or 12V. When they run at higher voltages, they become extremely hot. Extreme heat damages the LED lights or the soldering around them. Due to the heat damage LED lights start to dim, flicker, or may die entirely.

Voltage Selection

The most common LED strip and battery voltage combination is 12V DC. Unless you have a specific situation that requires something else, 12V should work just fine. If you want to use standard AA batteries, you can use a battery holder that creates a 12V voltage from 8x 1.5V AA batteries.

24V is better suited for LEDs.

It is through configuring the LEDs in a particular parallel vs series combination, that the voltage of an LED system can be made to match a particular power supply voltage. Typically, a 12V LED strip is configured with 3 LEDs in series per string.

How do you calculate light spacing? ›

A good general rule for placement is to divide the height of the ceiling by two. The result is the amount of space to leave between each light. For example, recessed lighting spacing for a room with an 8-foot-high ceiling would be 4 feet between each light. This will provide good spacing for general room lighting.

Each CFL or LED bulb typically gives the same amount of light as a 60-watt incandescent bulb while drawing 10 watts or less, which is equivalent to a current draw of 1/12 amp. Thus a 15-amp circuit can safely control 180 or more fixtures that use CFL or LED bulbs.

Therefore, a twenty-amp circuit can handle up to 38 LEDs. However, if you are using a 15-amp circuit, then you can install up to 30 LEDs. It is important to remember that putting more than 12 lights on a 20-amp circuit can cause the circuit to overheat and burn out.

Exceeding the rated load for the circuit wiring will trip the breaker, closing down the entire circuit. Without a breaker, an overload would overheat the circuit wiring, which could melt the insulation and cause a fire.

A right to light is a legal right to a particular amount of light in a room or space. Using the 50:50 rule, a right to light injury is defined as loss of light when the light within a room is reduced to less than 50% of the original amount. Not everyone has a legal right to light, so it's best to check.