Nitecore Thumb Leo flashlight review

1 x unspecified LED, 1 x unspecified 365nm UV LED
45 lm output
150 cd intensity
integrated Li-Ion battery

The Nitecore Thumb Leo flashlight released in 2017. It uses 1 x unspecified LED, 1 x unspecified 365nm UV LED, no reflector and integrated Li-Ion battery. The powerful emitter in this flashlight provides up to 45 lm output, 150 cd intensity, and a beam distance of 24 m.

Interested to see if the Nitecore's flashlight is a hit? Find out soon!

Table of Contents

The content of this article reflects our own experiences and viewpoints. We aim to offer insights on a topic, and we hope others find it helpful and motivating. Additionally, we make every effort to provide accurate and comprehensive coverage. If you found an error or something lacking in the specifications for the Nitecore Thumb Leo, then tell us.

Nitecore Thumb Leo / THUMBLEO

The Thumb Leo is an impressive flashlight that offers both power and reliability. Its robust build and outstanding illumination make it a versatile lighting instrument. This light has 3 modes of lighting. Without mode memory, this flashlight always starts in the default mode. This USB rechargeable flashlight is small and light. It is easy to carry.

Nitecore Thumb Leo specifications

NameThumb Leo
Rated 3 / 5 based on 1417 user votes.

A flashlight provides reassurance and confidence. It is helpful in unfamiliar or dangerous places.

Nitecore Thumb Leo / 2

Body, materials, weight, colors

Weight25 g
Length74 mm
Head diameter24 mm

The 25 g flashlight may not provide the same level of brightness or features as larger models. The length of a flashlight can affect how it feels in your hand and how you can grip and maneuver it. This flashlight features a captivating black color.

Nitecore Thumb Leo / 1

System, LED, lens, reflector

Emitter1 x unspecified LED, 1 x unspecified 365nm UV LED
Color temperature6500 K
Switchelectronic side

The color temperature choice depends on the light's use and personal taste. Some flashlights with electronic switches have programmable features. They allow users to customize the behavior of the flashlight.

Nitecore Thumb Leo / 3

Performance, flux, intensity, throw

Flux45 lm
Intensity150 cd
Throw24 m
CD/LM factor3.33

You mainly need a flashlight for basic tasks like finding keys or navigating in dimly lit areas. 45 lm can be enough. It can also be enough for occasional use around the house. 150 cd can make things quite bright. It's enough for many everyday tasks. The throw distance is the farthest distance the flashlight can light an object. The candela per lumen (cd/lm) ratio can be used to determine if a flashlight has a spot or flood type beam.

Software, user interface, modes

Modes3 modes
Mode memoryno
Ramping modeno

A flashlight's modes are different output settings or brightness levels. They can be chosen to meet different needs and preferences. The Thumb Leo's SOS mode produces a specific sequence of long and short flashes. It signals distress or emergency.

Features, battery, protections

Batteryintegrated Li-Ion battery
Battery indicatoryes
Charger portmicroUSB
Thermal regulationno
Impact resistance1 m
SpecialsUV light
adjustable head
red/blue light

The Thumb Leo flashlight utilizes integrated Li-Ion battery as its power source. The battery indicator helps users check the battery status. It also estimates how much runtime they have left before recharging the battery. The built-in charger allows for convenient and versatile charging. You can use various USB power sources to recharge the battery. The Thumb Leo flashlight lacks built-in LVP. You should use a protected battery to prevent over-discharging.

Flashlights without thermal protection may be more susceptible to overheating under extreme conditions. The flashlight has an IPx8 rating. It can withstand being submerged in water beyond 1 meter for a prolonged period. The manufacturer specifies this. A flashlight's impact resistance can vary. It depends on its design, construction, and intended use. Extra LEDs have different colors or modes, they can help with specific tasks. Thumb Leo's UV light can reveal urine and other stains left by pets. It works on carpets, furniture, and other surfaces.

Accessories, package contents

Package contentskeyring

According to the ANSI/NEMA FL1 Standard, we measure the performance of the Thumb Leo flashlight 30 seconds after switching on the light. The ANSI/NEMA FL1 2009 Standard is a set of flashlight performance guidelines.

Conclusion, pros and cons

This Nitecore flashlight, like any other, has its strengths and weaknesses. Let's take a close look at both sides to understand this flashlight better. I share my thoughts on its standout features and the parts that might need improvement. Keep in mind, these are just my opinions, and you might have a different perspective.


  • lightweight
  • side switch
  • multiple modes
  • SOS/beacon function
  • integrated battery
  • battery indicator
  • USB charger
  • waterproof
  • auxiliary LEDs
  • UV light


  • plastic body
  • unspecified LED
  • cool light
  • moderated performance
  • low intensity
  • no mode memory
  • no LVP
  • no thermal regulation
  • non-magnetic


Nitecore Thumb Leo / THUMBLEO photo 1.
Nitecore Thumb Leo / THUMBLEO photo 2.
Nitecore Thumb Leo / THUMBLEO photo 3.
Nitecore Thumb Leo / THUMBLEO photo 4.
Nitecore Thumb Leo / THUMBLEO

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David Hagon
I love bushcraft and flashlights. I find joy in mastering wilderness survival skills and exploring the realm of illuminating gadgets. Bushcraft isn't just fun, it's a learning journey. I form a strong bond with nature. It's more than a hobby, it enriches me in practical and spiritual ways.
FlashlightChart.com / Flashlights / Nitecore / Nitecore Thumb Leo (2017)