What Wattage Lights to use for Turtle Basking?

Although turtles do commonly exhibit the aloofness and independence normally associated with cats or rabbits, they’re not exactly low-maintenance animals.

To remain in tip-top condition, they require a highly controlled environment, and one of the most important aspects of their contrived habitat is the basking (heat) lamp.

What’s the Best Turtle Basking Light Wattage

It may seem fairly insignificant, but basking and UV light couldn’t be more essential to your turtle’s well-being. They’re essentially their sun.

Imagine how catastrophic it would be for us and our planet if our sun suddenly began to dim or burned twice as hot. This is why you need to pay extra close attention to your basking lamp wattage.

What is Wattage?

Simply put, the wattage of your light defines how bright it will shine, the heat it will give off, and the energy it requires to function.

Basking lights are available in a selection of different wattages, so it can be a confusing topic for turtle owners to navigate.

What are Basking Lights and Why do I Need One?

A basking light isn’t exactly a specialist light. You can use a simple halogen bulb in a directional enclosure.

As long as it transfers plenty of heat and illuminates, it can be used as basking light.

Light Cycles

Turtles need basking lights for a number of reasons. Much like us, they need appropriate dark and light periods to regulate their circadian rhythms.

If for some reason these rhythms are disturbed and your little friend only experiences broken sleep, they’ll develop a significant amount of stress which can lead to a malfunctioning immune system, sluggishness, and other more severe health issues.

To avoid all this, it’s generally recommended you keep their light on between 8-10 hours a day, then switch them off for 10-12 hours of darkness. If you’re having trouble with these timings, why not use a timer to keep you on track?


Being cold-blooded, turtles need access to external sources of heat to raise their internal temperature, and they do this by basking.

Basking lights heat up your turtle’s basking surface and air, allowing them to warm their cold blood for a period.


By providing the heat a turtle would naturally oak up in the wild from the sun, a basking lamp also aids a turtle with digestion.

This brief period of inactivity allows food to be fully processed, ensuring your turtle is taking in all the nutrients it has to offer.

Do Basking Lights Emit UV?

Basking lights can contain UVA, but they’re not strictly UV bulbs. A UV bulb emits the same ultraviolet electromagnetic radiation as the sun. UVB is dangerous to humans, but turtles absolutely love it.

They also absorb the vitamin D, then convert it internally into vitamin D3 which helps them digest and use the calcium in their diets to grow big and strong.

Dual Lights

The easiest way to provide your turtle with all its essential lighting needs is to purchase a dual light that emits both the heat of a basking light and the UVB of a UV light from one fixture.

A dual lamp saves space, and time on installation, and really just simplifies the whole situation, so if you’re looking to streamline your tank, they’re a great place to start.

What Watt UVB Bulb to use for Turtles

I wish it was as easy as giving you a single number, but unfortunately, it’s a more complex matter than that. The correct wattage you need depends on a few variables.

50-75 Watts

If you have a smallish aquarium with a capacity of 55 gallons or less, own fewer than three turtles, or have a relatively small basking area, you won’t need such a powerful lamp.

55-75 watts should be plenty enough to keep the basking area between 90-95°F.

100 Watts

If, on the other hand, you have a larger tank that can hold 75 gallons of water or more, have three or more turtles, or have a large basking spot, you’ll need a bulb with more juice.

A 100-watt UV bulb should be more than capable of maintaining that essential 90-95°F basking temperature across a wider area.


If you have an extra-large tank and sizeable basking spot, you may need to pull out the big guns.

It’s not unheard of for large turtle habitats to include 150-watt bulbs to ensure optimal basking temperatures are maintained.

How Far Away Should a basking Light be From a Turtle?

A great way to increase or decrease basking temperature is by moving the light either closer or further away from the basking area.

With weaker 50-watt lights, they’ll need to be much closer to the area than their 100-watt counterparts.

The Best Turtle Basking Platform Ideas

The ideal basking light distance is also dependent on the size and material of your basking area, the light manufacturer’s recommendations, and regular manual temperature checks.

That said, you’re probably looking at a distance of between 5 and 12 inches.

A 50-watt bulb will rarely provide enough heat from more than 7 inches away, and will probably provide too much heat if it’s any closer than 5 inches.

For 75-watt bulbs, the correct distance normally lies between 7 and 9 inches.

100-watt bulbs should be distanced between 9 and 12 inches from the surface of the basking area.

150-watt bulbs should probably be at least 12 inches from the surface.

Do remember, these aren’t universal measurements, but rather approximations.

Every tank and its contents will be slightly different, so you’ll need to experiment with custom distances until you get that temperature just right!

Also Read: How Long Should Turtles Bask in the Sun?

Basking Light Placement

So, you know how to handle the distancing of your UV light; the next challenge you face is to position it correctly in the tank. Ideally, the light will be set completely to one side of your aquarium, so it covers the whole basking area

The light needs to be to one side because you really only need it to heat up the one spot. Thermoregulation is all about balance.

Turtles need cool areas as much as they need a lovely warm basking spot, besides, your water temperature should be regulated independently and shouldn’t rely in any way on the basking light.

Cool Side

They’re not strictly necessary, but if you like, you can use what’s known as a cool side lamp. These lamps provide illumination, but they don’t generate as much heat as basking lights.

The idea of introducing cool side lamps to your setup is that it eliminates dark spots in a captive turtle’s habitat that could disrupt their circadian rhythms. A cool lamp ensures that your aquarium is lit throughout.

Temperature Gradient

If you want your beloved turtle to be as comfortable as possible, you should experiment with temperature gradients. A temperature gradient is the gradual change in temperature from one side (hot basking area) to the other (cool side).

Introducing this gentle lateral thermal spectrum lets your turtle pick exactly the temperature they need at any given moment.

A perfectly orchestrated temperature gradient would run from a 90-95°F (hatchlings and young turtles) or 85°F (mature turtles) basking spot into an 80-85°F midsection, then into a 75-80°F cool spot.

Light Maintenance

Basking light bulbs are no more equipped to deal with extended periods of use than the average light, therefore, their power will begin to eventually wane.

This is bad news for your turtle child that will likely spend more time than they should basking, trying to raise their internal temperature. This may also lead to undue scute shedding and respiratory issues.

The best way to ensure your turtle doesn’t fall on such hard times is to change your bulbs at regular 6-month intervals. Even if the manufacturer of the bulb claims it will run full power for over 9 months, it’s better to be safe than sorry.

What Happens if The Basking Light is Too Hot?

Just as a basking light can become too weak and harm your turtle, so can they be too powerful and harm your turtle.

If your basking area is too hot, your turtle will spend most of its time in the cooler areas of its tank and refuse to bask. Consequently, it will lose its appetite, become deficient in both UVB and calcium, and if the matter’s not seen to, possibly even die.


It’s essential that you equip yourself with temperature measuring devices.

A standard thermometer can be good for keeping tabs on water temperature, but I recommend an infra-red temperature gun for monitoring basking area and surface temperature.

Basking Light Safety Considerations

Secure Mounts

The very last thing you want is for a light to fall from its place and possibly electrify the water in your turtle’s enclosure.

Even if you own a box turtle, and there’s only drinking water in their tank, you should never allow your turtle to actually come into contact with a light or its wiring. Moreover, a dislodged light is going to completely destroy the precise temperature spectrum of your tank.

If lighting has fallen into your tank, before you do anything, turn the power off at the mains. In fact, you should never reach into your tank for any reason if there are live wires around, so as a general rule, unplug everything before you go diving in there.

Fixture Compatibility

You’ll need to ensure that your light fixture can handle the wattage of the bulb you need for your turtle’s basking area.

If you severely overpower the fixture, the bulb will burn it out and it will stop working, and not only will your turtle be left in the cold, it’s a huge fire hazard.

Eye Health

Although looking directly into regular basking lights isn’t as harmful as looking directly into a UV light, it’s still a good idea to keep your peepers safe by avoiding eye contact.

This is especially pertinent if you’re using a dual light with integrated UVB rays.

Fahrenheit not Celsius

This may seem like silly advice, but it couldn’t be more important. Guideline temperatures for turtle habitats are almost always given as Fahrenheit.

Make sure you don’t confuse things and measure by Celsius or – as horrible as it sounds – you’ll wake to turtle stew.

Summing Up

Let’s quickly run over some of the key points of the article just so you’re extra sure how to move forward.

  • The wattage of your basking lamp will depend largely on the size of your tank, the basking area, and how many turtles you keep, but really, all that matters is that it can maintain a 90-95°F basking temperature (85°F for mature turtles).
  • You can alter temperature by lowering or lifting the basking lamp, but it should always be kept to one side of the tank to facilitate an optimal temperature gradient. Equip yourself with all the thermometers you need to keep tabs on each area of your tank.
  • To facilitate healthy circadian rhythms, you need to keep your lights on between 10-12 hours a day, but you can use a timer to make things easier.
  • Basking and UV lights are separate entities for the most part, but if you wish to make life easier for yourself, you can buy dual lights that provide both heat and UVB.

As long as you learn your turtle’s temperature requirements, arm yourself with the correct gear, and heed the safety considerations, you and your turtle will live happy and healthy lives together.

Dorothy Razo

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