Should a Post Light Use 12W or 20W for Your Yard?

Most homeowners pick a post light based on looks alone, then discover the glow is either too weak for the driveway or so bright it washes out the porch. The real issue is matching wattage to the mounting height and the area you need to cover. A 12W LED fixture throws about 1,200 lumens, which suits a 4-foot post near a walkway, while a 20W unit pushes roughly 2,000 lumens for a 6-foot post over a driveway. The choice between them changes how your property reads at night, and it also changes the electric bill by roughly $1.50 per month.

I have installed hundreds of these fixtures over the years, and I can tell you that the energy-efficient outdoor post light market has shifted hard toward LED. The old 100W incandescent bulbs are gone, and the new fixtures use a fraction of the power while lasting 25,000 hours or more. That longevity matters because changing a bulb on a 9-foot post usually requires a ladder and a steady hand.

The Beam Pattern Matters More Than Lumens

A post light with a clear glass globe spreads light in all directions, which is great for a front yard but wasteful if you want focused light on a path. A frosted or seeded glass diffuses the beam and softens shadows, making it easier on the eyes when you walk up at night.

• Clear glass: best for wide, open areas like a cul-de-sac or a corner lot.
• Frosted glass: best for patios and seating areas where glare is a problem.
• Dark sky compliant shields: point light downward to reduce light pollution and keep neighbors happy.

For a standard 5-foot post, I usually recommend a fixture in the 15W to 18W range. That gives you around 1,500 to 1,800 lumens, which is enough to light a 12-foot by 12-foot area without creating harsh hot spots. If you have a long driveway that curves, you will want two fixtures at 12W each rather than one big 20W unit at the end.

Battery Backup Changes the Wattage Math

Many modern post lights come with an integrated battery backup that kicks in during a power outage. This is a great feature, but it changes the wattage equation. A 20W fixture will drain a typical 3,000 mAh battery in about 90 minutes, while a 12W unit can run for nearly 3 hours. If you live in an area with frequent storms, the lower wattage gives you more emergency light when you need it most.

The trade-off is brightness. A 20W fixture will clearly light a two-car driveway, whereas a 12W unit will leave the far corners in shadow. I have seen homeowners solve this by installing a 20W fixture on a motion sensor that dims to 30% output until someone approaches. That way, you get the high output when you need it and the battery life when you do not.

Sizing a Post Light to a 6-Foot or 7-Foot Post

The height of your post determines the ideal fixture size, and getting this wrong is the most common mistake I see. A fixture that is too small looks like a toy on a tall post, and one that is too large overwhelms a short post.

For a 6-foot post, the fixture body should measure between 22 and 26 inches tall. That proportion keeps the light source at eye level when you are standing on the lawn, which reduces glare. If you go with a 20W bulb in a 22-inch fixture, you get a solid pool of light that covers a standard parking pad. A black aluminum post light in that size is a common choice because the dark finish hides dust and pollen.

Which Material Holds Up to Rain and Snow?

The housing material determines how long the fixture survives outdoors. Die-cast aluminum is the industry standard because it resists corrosion and handles temperature swings from -20 degrees to 120 degrees Fahrenheit. Plastic fixtures are cheaper but tend to yellow after two or three summers in direct sun.

• Aluminum: heavy, durable, and paintable if you want to change the color later.
• Stainless steel: sleek and modern but shows water spots in hard-water areas.
• Plastic: lightweight and inexpensive but prone to cracking in freezing weather.

I always check the gasket around the globe. A silicone gasket keeps moisture out, while a foam gasket compresses over time and lets water seep into the socket. That moisture is the main reason LED drivers fail, not the LEDs themselves. If you live in a coastal area, look for a fixture rated IP65 or higher, which means it is fully sealed against dust and low-pressure water jets.

Photocell Sensor Placement for Reliable Dusk-to-Dawn Operation

Most post lights include a photocell that turns the light on at dusk and off at dawn. The sensor needs a clear view of the sky, so do not mount the fixture under a deep eave or next to a bright window. I have seen fixtures cycle on and off all night because a porch light was reflecting into the sensor.

If your fixture has a separate sensor on a wire, mount it on the side of the post facing north. That avoids direct sunlight during the day, which can trick the sensor into turning off early. A matte black post light with a top-mounted sensor is easier to position because the sensor sits above the globe.

The Real Cost to Run One for a Year

The operating cost is lower than most people expect. A 15W LED post light running 10 hours per night uses about 55 kWh per year. At the national average of $0.16 per kWh, that is roughly $8.80 per year. Compare that to an old 100W incandescent bulb, which would use 365 kWh and cost about $58 per year. The LED pays for itself in under two years, even if the fixture costs $80 more upfront.

If you want to cut that cost further, look for a fixture with a dusk-to-dawn sensor and a timer. Setting the light to turn off at 1 a.m. instead of running until sunrise saves about 40% of the annual cost. A modern post light with a timer gives you control without needing a smart home system.

Cleaning the Globe Without Scratching It

Dust and dead bugs reduce light output by up to 30% over a season. Clean the globe twice a year with warm water and a few drops of dish soap. Use a microfiber cloth for glass, but switch to a soft sponge for plastic globes because abrasive pads leave fine scratches that hold dirt. Rinse with a hose and let it air dry before turning the light back on.

Check the screws on the fixture head once a year. Aluminum expands and contracts with temperature changes, which can loosen the mounting bolts. A quick tighten with a screwdriver prevents the head from wobbling in the wind and cracking the gasket seal. A bronze post light with a glass globe tends to hide the small water streaks that show up on darker finishes, so it looks cleaner between washes.

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