ANSI FL1 standards are used to ensure that all LED Flashlights are tested and rated according to the same criteria. These standards are voluntary. Renowned  Manufacturers like hokolite.com/collections/flashlight do their own testing. However, most big brands include the following performance data on packaging.

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Light Output

In lumens This measure is the intensity of light that comes from the flashlight at the brightest setting. You may see it for different light settings. It is useful as a comparison tool but it does not give the full story on brightness. 

Beam Distance

Measuring in meters. This is the distance the light will shine before it dims to the same level as a full moon. For safe and cautious outdoor travel, full moon illumination is sufficient. The brightness setting chosen will affect the distance.

Run Time

Measuring in hours. It takes for light output to fall to 10% of its rated output with new batteries. This is rounded up to the nearest quarter hour. The light output can decrease gradually or be largely constant, then suddenly drop.

Impact Resistance

Measuring in meters. To test lights, drop them six times on concrete at the recommended distance. This is done to make sure the light continues to function after accidental drops. This test is not intended to determine if the light can withstand being hit with heavy objects, run over, or used to strike other objects.

Water Resistance

The IPX system is used to determine the rating. If you use your light outdoors or near water bodies, water resistance is essential. There are three ratings:

After the impact test, an IPX4 rating is indicated. This means that it is splash-resistant from all angles. Indicates water submersion rating. Also after impact testing.

• IPX7 Temporary immersion: Up to 30 minutes at 1m depth
• IPX8 Submersion: Up to 4 hours at the indicated depth