One of the easiest methods for how to spot a fake NFL jersey is to look at the manufacturing country on the inner tag.
Try to give the jersey a good up-and-down to make sure that all of the decals match up to an authentic NFL jersey, like the direction of the Nike Swooshes on the shoulder and the NFL shield on the collar.
These are always made in a specific kind of way, and counterfeiters often have a difficult time reproducing them.
Always trust your instincts. If the numbers look off or the font on the jersey is wrong, go with your gut. You know your team better than any counterfeiter.
How To Spot A Fake NFL Jersey
Tip #1: Manufacturing Country and Nike Swoosh
All authentic NFL jerseys are made either in Honduras or Guatemala. 
No matter how convincing a jersey looks, if it’s made anywhere other than in those two countries, you’ve spotted a fake NFL jersey.
Then there’s the Nike Swoosh logo on the shoulders, which should always be facing forward. Counterfeiters seem to get this one wrong a lot so be on the lookout for this.
Tip #2: NFL Shield on Collar
On every authentic NFL jersey is the NFL shield rubberized into the collar.
There are some obvious tells that you’ve spotted a fake NFL jersey, like if the worksmanship and the seams look shoddy.
But another tell is if the NFL shield is embroidered on the collar, rather than rubberized.
That’s because Nike has developed the neckline in a way that prevents the label from flipping up and rubbing against your skin, which can happen when the collar is embroidered.
So, to know you’ve spotted a fact, run your hand against the NFL shield and feel whether it is embroidered and raised or if it is rubberized and lays fall against the jersey.
Tip #3: Product Tag
All authentic NFL jerseys have the product tag on the left sleeve of the jersey.
This little detail is sometimes omitted by counterfeiters, as most people don’t think to look for this.
But in an effort to be transparent, Nike has revealed that all product tags are on the left sleeve.
You should also have a closer look at the tag, as there should be a hologram sticker on it with the NFL shield.
When you look at the shield and move the tag around, it should shine multiple colors. If it stays just one plain color, it means that it’s a fake.
This is a good giveaway, as holograms are expensive and most counterfeiters simply won’t foot the bill for these.
Tip #4: Jersey Number and Nameplate
Jersey numbers should always lay flat against the jersey. If the numbers appear bubbly underneath or do not lay evenly flat, then you’ve spotted a fake NFL jersey.
Also, make sure to double-check that the fonts are correct, as some counterfeiters can’t be bothered to match these up with authentic jerseys.
Sometimes, the difference is subtle but sometimes it’s not.
An easy way to do this is to simply load up the NFL shop and compare the quality and fonts to the jersey you’re looking at.