The Marine Corps takes a conservative approach to personal appearance, in terms of grooming and uniform standards. Eccentricities in dress or appearance that detract from uniformity and team identity are not permitted.
Following this principle, the Marines have detailed guidelines governing what kinds of tattoos are allowed. The Corps most recently updated its policy in 2016 with Bulletin 1020. While there were some changes, the basic policy remains the same as previous policies. Tattoos are permitted as long as they can be covered by the standard physical training uniform of a green t-shirt and shorts. If they follow these guidelines, Marines can have as many tattoos as they want.
Under MCBUL 1020, there are several official ways to measure tattoos to make sure they're in compliance with Marine Corps rules. There are both elbow-measuring and knee-measuring tools that can be used to make sure the uniform would cover a tattoo (ideally before it's applied to the skin).
Sleeve Tattoos and Brands in the Marines
A sleeve tattoo is a very large tattoo, or a collection of smaller tattoos, that covers or almost covers a person's entire arm or leg. These are prohibited in the Marine Corps.
Half-sleeve or quarter-sleeve tattoos—that covers, or almost covers the entire portion of an arm or leg above or below the elbow or knee—that are visible to the eye when wearing standard physical training gear are also prohibited.
Also, Marines may not have tattoos or brands (any marking that can't be easily removed) on the head or neck, inside the mouth, or on the hands, fingers, or wrists. One exception that is allowed is a single band tattoo of no more than three-eighths of an inch in width on one finger. Many Marines will do this tattoo in lue of wearing a wedding band.
Other Types of Tattoos Prohibited by the Marines
Tattoos or brands that may be considered prejudicial to good order, discipline and morale, or are of a nature to bring discredit upon the Marine Corps are not allowed. These may include but are not limited to, any tattoo that is sexist, racist, vulgar, anti-American, anti-social, gang-related, or related to an extremist group.
Cosmetic Tattoos in the Marine Corps
The Marine Corps allows cosmetic tattooing in certain circumstances. Cosmetic tattooing refers to medical or surgical procedures conducted by licensed medical personnel. For example, an individual may be medically authorized to get a tattoo on scar tissue to disguise it or make it less noticeable.
Tattoos in Other Branches of the U.S. Military
All the branches of the Armed Forces have policies governing tattoos. They all tend to be similar to the Marine Corps' policy. Beginning in 2015, the Army loosened its rules to assist with recruiting efforts. All of the branches prohibit tattoos that are derogatory in nature or are too large or obtrusive. The goal is to keep Marines and other troops as uniform as possible, right down to their skin.