How to Choose Casual T-Shirts for Men | Fit by the Numbers

Choosing a casual men’s T-shirt starts with your chest measurement and the brand’s own size chart, not the S/M/L label.

Most men grab whatever size they’ve worn for years and end up with a tee that either drapes like a tent or strains across the chest. The way to choose casual T-shirts for men that actually fit is to measure your chest, waist, and hips, then compare those numbers against the brand’s chart. Because size names differ from one company to the next, the label means almost nothing until you’ve checked the numbers behind it.

Why the S/M/L Label Isn’t Enough

Brands use the same letters to mean very different things. Nike’s men’s tops chart runs from XXS (chest 28.1–31.5 in) up to 4XL (chest 58–63 in), while ASOS lists a separate range from XXXS (30–32 in chest) to XXXL (46–48 in chest). A medium at one company might match a large at another. That gap is why relying on your usual size is the fastest route to a poor fit.

The fix is simple: measure yourself, then check the chart for the specific shirt you want. Brands like Nike also split their charts into standard and tall variants, so a tall medium is a different product from a regular medium. Confirm which one you’re looking at before you order.

How to Measure for a T-Shirt

Grab a soft tape measure and follow these steps, keeping the tape horizontal the whole time.

• Chest: measure around the fullest part of your chest, under your armpits.
• Waist: measure around the narrowest part of your waist, usually just above the belly button.
• Hips: measure around the fullest part of your hips.

If you’re between sizes on the chart, choose based on the fit you want. Nike’s guidance is straightforward: order the smaller size for a tighter fit or the larger size for a looser one. When you shop online, you can also measure a T-shirt you already own that fits well. Lay it flat, measure the width from armpit to armpit and the length from the collar to the hem, then compare those numbers to the garment measurements on the product page. The listed chest size equals the flat width multiplied by two, so a shirt that measures 20 inches across is a 40-inch chest.

What a Well-Fitted T-Shirt Should Look Like

Once the numbers line up, the look matters just as much as the measurement. A good casual tee should hit these marks.

• Shoulders: the seam should sit right at the edge of your shoulder, not droop down your arm.
• Chest: the fabric should skim your chest without pulling tight or pouching out.
• Length: the hem should land around mid-fly, not bunched at your waist or hanging past your hips.

Fit names tell you what to expect. A close fit runs true to size. A regular fit works in your usual size, though you can size up if you’re between measurements. A relaxed fit is meant for layering, so plan to go one to two sizes up from your normal size. If you want a tee for layering under a flannel or hoodie, factor that room into your choice before you order.

Neckline comes down to personal style. Crew necks are the default casual look and layer cleanly under almost anything. V-necks suit men who prefer a more open collar or want to show a bit of chest. Neither is objectively better — pick the one you’ll actually wear.

How to Buy the Right Size Every Time

The whole process collapses into a five-step routine that takes less than five minutes.

1. Measure your chest, waist, and hips with the tape horizontal.
2. Open the brand’s size chart — not a generic one, the brand’s own.
3. Match your numbers to the chart for the specific shirt, including tall or relaxed variants.
4. If you’re between sizes, pick based on desired fit: smaller for snug, larger for loose.
5. For online orders, compare the shirt’s garment measurements against a tee you already own.

One warning applies across every brand: don’t assume all companies use the same chest ranges. They don’t, and the charts prove it. A 40-inch chest might map to a medium at one store and a large at another. The label is a starting point, not a verdict.

Once you know your numbers, you can shop with confidence. If you’re ready to look at specific options, our roundup of the best casual T-shirts for men breaks down top picks by fit and value. The size chart does the measuring; the roundup does the comparing.