Tank top or T-shirt under a shirt
Short answer: A tank top is thin and hides best under a shirt with an open collar, while a T-shirt gives more coverage and a little extra warmth. Choose by the shirt fabric, the neckline and the season.
What the layer under the shirt actually has to do
The layer under the shirt should absorb sweat, protect the shirt fabric from the skin and stay out of sight. It should not add bulk, and it should not ride up or gather at the waist. Both a tank top and a T-shirt can do the job, but in different ways. The tank top adds the least bulk, while the T-shirt covers more of the torso and the underarms, so decide first what you want from the layer before you choose.
The tank top: light and almost invisible
A tank top has no sleeves, so there is no edge that can show through at the upper arm on a white or pale shirt. It suits warm days, shirts with an open collar and people who warm up quickly. The drawback is that the underarms are not covered, so sweat can reach the shirt sleeves, and the straps may be visible if the collar stands open. See bamboo tank top for men for an overview of the thin styles.
The T-shirt: more coverage and warmth
A T-shirt with short sleeves protects the shirt sleeves from sweat and gives an extra layer, which is welcome in winter or in a cold office building. Choose a crew neck if the shirt is buttoned all the way up, and a V-neck if it is open at the top, so the edge does not peek out. The sleeve should end above the shirt armhole, and the fabric should be thin enough not to create lumps at the shoulder.
Colour, cut and visibility
A white undershirt beneath a white shirt can show through as a sharp contrast. A skin toned or pale grey layer is often less visible than white, especially under thin cotton or linen. Dark shirts tolerate a black or dark grey undershirt. The cut should follow the body so that no loose folds show through the fabric. Let the hem be long enough to stay in the trousers without rolling up.
The fabric under the shirt
This is where the fabric makes a big difference. Viscose from bamboo is soft and smooth, so the shirt glides without catching, and it absorbs moisture without feeling clammy. A thin, smooth surface gives fewer creases in the shirt and less rubbing at the neck. If you spend many hours in a shirt, it is these small differences that make the day more comfortable. See also bamboo underpants for men if you want the same feel all the way through.
Our recommendation by situation
For summer and warm offices the tank top is the right choice, especially under a light shirt with an open collar. For autumn, winter and cold rooms the T-shirt gives more warmth and protects the sleeves. If you have an active day with sweating, the T-shirt is safer because it covers the underarms. Consider owning both, and take the layer that suits the weather and meetings of the day. See also Decoy. Wash at 30 to 40 degrees and avoid fabric softener.
Frequently asked questions
Should the undershirt be tucked in
Yes, preferably. If it is long enough it stays put and does not roll up. If it is too short, choose a longer style for work days.
Is a white undershirt visible under a white shirt
Often, especially if the fabric is thin. A pale grey or skin toned layer is usually less visible, and a close fit also helps.
Which neckline should I choose
A crew neck for a fully buttoned shirt and a V-neck if the top button is open. That way the edge does not peek out.
