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Black Diamond Cosmo Review

Black Diamond Cosmo 2018
Price:   $30 List | $23.99 at MooseJaw
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Pros:  Lightweight, small size, great price
Cons:  Much less brightness than alternatives
Bottom line:  Lightweight, this option is not nearly as bright as similarly sized models.
Editors' Rating:   
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Measured Max Beam Distance:  29 m
Claimed Distance:  50 m
Measured High Mode Run-time (ANSI):  7.1 hrs
Manufacturer:   Black Diamond

Our Verdict

While this is a good headlamp, we implore you to spend another $10 and get something like the Black Diamond Spot which has much better beam brightness and quality combined with a very respectable battery life. The Cosmo is a middle of the road kind of light. It offers average performance and average battery life at an average price. If you are on a budget, look to the Energizer 3 LED which scored just a little lower for a fraction of the price. Or if you're looking for a lighting powerhouse, check out the Coast HL7.

RELATED REVIEW: The Hunt for the Best Headlamps

Our Analysis and Hands-on Test Results

Review by:
Jediah Porter and RJ Spurrier

Last Updated:
May 10, 2015


The New Black Diamond Cosmo vs. The Older Version

The Black Diamond Cosmo has been upgraded since we tested it. The list price remains $30 and it's available in new colors. The redesigned Cosmo boasts 200 lumens, as well as six different modes, and is now waterproof.

Check out a side-by-side comparison below, with the latest version of the Cosmo shown on the left (shown in the color Grass) and the older version pictured on the right.
Black Diamond Cosmo 2018
Black Diamond Cosmo

Hands-On Review

This is an average performing headlamp that falls into the tough $30 price range. Just a little more money gets you a much higher performance headlamp, while less expensive models don't score too far behind this one. The Cosmo is exceptional at one thing: very long battery life when on low mode.

Performance Comparison

This $30 headlamp runs for a long time on low mode.
This $30 headlamp runs for a long time on low mode.

Trail Finding

A score of 7 for trail finding is very respectable, especially for a $30 headlamp. But if you spend just another $6, you can get a trail finding powerhouse with the Coast HL7. As you can see in the beam comparison, the coast shines much further.
Beam Distance Photos

Black Diamond CosmoCoast HL7

The Coast gets that awesome beam, however, by burning through batteries very fast. Perhaps a better comparison is with the Cosmo's big siblings, the Black Diamond Spot and Black Diamond ReVolt which both have solid battery life. What you get for your extra $10 in upgrading from the Cosmo to Spot is well worth the investment.
Beam Distance Photos

Black Diamond CosmoBlack Diamond Spot

Close Proximity

In comparing the Black Diamond Spot and Cosmo, two products from the same manufacturer and priced just $10 apart, it is remarkable that they can vary so much. The Spot, in close proximity mode, casts a very even beam. The Cosmo has a hot spot in the middle and not very even light.
Close-proximity Beam Pattern

Black Diamond CosmoBlack Diamond Spot

Battery Life

Battery life is where the Cosmo edges slightly ahead of the Spot. It lasted seven hours in our ANSI measured high mode runtime tests. This is much better than the Spot (3.7 hours) and Coast (3.4 hours). During that test, the beam power starts much lower on the Cosmo, which does not make for the best direct comparison. In other words, it is no mystery as to why the Cosmo lasts so much longer on the same batteries than the brighter lights. The brighter bulbs in the more expensive lights consume more battery power right away than those in the Cosmo. Confused? What is ANSI? See our detailed description in the full Headlamp Review.

We did not measure low mode runtime, but the Cosmo's claimed 250 hours is one of the highest of any headlamp in the review. We can extrapolate that, given the relatively long high-mode run time, the Cosmo will run a very, very long time in low mode on fresh batteries.

The Cosmo takes 3 AAA batteries.
The Cosmo takes 3 AAA batteries.


This light casts a beam 29 meters long in our measured max beam distance tests. This compares with 71 m for the spot and 131 m for the Coast. 29 m is not bad, it's just not that impressive for a $30 headlamp when the Coast goes three times as far for only an extra $6.

A photo of the beam distance of the BD Cosmo. It shines 29 meters.
A photo of the beam distance of the BD Cosmo. It shines 29 meters.


At 94 grams, this is a compact but not ultralight headlamp. It is about the same weight as the Spot. For comparison, the featherweight champion Petzl e+LITE is less than a third the weight at 30 g.

Best Applications

Use this light when it is essential to have long battery life. Otherwise, we think there are better options out there.


The thirty dollar price point is a tough spot. Just a little more money gets you the top scoring headlamps in our review. And for a total of $12, you can get the well-performing Energizer 3 LED, which is more attractive to those on a budget.


This is a solid light but there are just too many competitors that either score much better for another $6-10 or score just a little lower at a much lower cost. The Black Diamond Spot, for example, performs significantly better for only $10. It has a nearly identical form factor and mass with a much better beam. The Coast HL7 is a light-emitting powerhouse for only $6 more. And for a mere $12, the Energizer 3 LED scored slightly better than the Cosmo.
Jediah Porter and RJ Spurrier

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Most recent review: May 17, 2016
Summary of All Ratings

OutdoorGearLab Editors' Rating:   
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Average Customer Rating:   
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100% of 1 reviewers recommend it
Rating Distribution
2 Total Ratings
5 star: 50%  (1)
4 star: 0%  (0)
3 star: 50%  (1)
2 star: 0%  (0)
1 star: 0%  (0)
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   May 17, 2016 - 10:58pm
Niii Pawww · Climber · Los Angeles
This is the best headlamp ever!

Bottom Line: Yes, I would recommend this product to a friend.

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