3157 VS 4157 Bulbs | What’s The Difference?

In this article, we’ll be taking a look at the major differences between 3157 and 4157 bulbs.

Because of their similar naming schemes and design, these two bulbs are often considered to be interchangeable.

While that is true, there are some subtle differences between the two in terms of performance and longevity.

The biggest difference between these two bulbs is lifespan.

Specifically, 4157 bulbs are a newer design that is longer lasting than its 3157 counterparts. Furthermore, 4157 bulbs feature nominally higher brightness output.

Having tested the vast majority of options for both types of bulbs, we can help you make a more informed decision about which one to buy.

Keep reading for more info on the differences between 3157 and 4157 bulbs.

Lifespan of this bulb is shorter Newer, longer lasting bulb design
Does not have Krypton gas in the bulbUses Krypton gas in the bulb
Dimmer bulbSlightly brighter light output
Rated for 27 wattsRated for 29 watts

3157 and 4157 Bulbs Compared

Power rating

There is a slight difference between 3157 and 4157 bulbs when it comes to the power rating and wattage. 3157 bulbs are rated for 27 watts whereas 4157 bulbs are rated for a slightly higher 29 watts.

Day to day, we did not notice the biggest difference in terms of light output or visibility. However, 4157 bulbs do offer a bit more clarity when viewed up close.

Gases used in the bulb

Being a new design of bulb, 4157 bulbs utilize Krypton gas in the bulb which allows for better, more clear light output, and extended lifespan when compared to 3157 bulbs which do not have Krypton gas in the bulb.


Our testing concluded that the difference in brightness between these two bulbs is not that noticeable in the real world. However, there is a difference on paper. 4157 bulbs are rated to produce a couple more lumens than 3157 bulbs.

However, we would like to reiterate that the difference in brightness alone should not influence your buying decision when it comes to these bulbs.


The most noticeable difference, and one that should definitely be under consideration when trying to choose between these two bulbs, are their lifespans.

3157 bulbs are an older design of bulb and do not last as long as 4157 bulbs.

4157 bulbs utilise better materials, which are more resistant to heat and Krypton gas in the bulb which increases bulb longevity.

In fact, 4157 bulbs are rated to last over four times as long as 3157 bulbs.


We tested a number of different options for both 3157 and 4157 bulbs and found them all to be interchangeable. They have the same exact bulb base, albeit made of slightly different materials, and the connectors are shaped the same as well.

As for the slight difference in power rating, you don’t have to worry about blowing a fuse or getting decreased performance if you swap bulbs. The wattage of both bulbs is within allowable tolerances and will not cause any problems.


So, to sum up, 3157 and 4157 bulbs are quite similar and only differ in a few ways.

After testing most of the options for each bulb, we have concluded that of the two, 4157 bulbs are the superior choice. No matter how small, there is a difference in brightness and power of the bulb.

But what really seals the deal is the difference in longevity. 4157 bulbs feature a four times longer lifespan, compared to 3157 bulbs. That means you will have to replace bulbs less often, while still enjoying as good as, if not better performance than with 3157 bulbs. All said and done, 4157 bulbs offer the best bang for your buck.

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Richard Nickleson is the author and owner behind Headlight Reviews. He first started the site as a hobby to share his insights on car parts and specifically headlight bulbs, but it soon ballooned and now he writes on all topics surrounding headlights bulbs. If you've got a bulb question, contact Richard here.

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