Cockroaches have flat, oval bodies with long antennae. The German cockroach is small and tan, about 13 to 16 mm, with two dark stripes behind the head. The American cockroach is large and reddish-brown at about 1.5 inches. The Oriental cockroach is dark and glossy.
The fastest way to answer "what do cockroaches look like" is a simple framework we call the Size-Color-Location (SCL) check: read the roach's size, then its color, then where you found it. Those three signals point almost every time to one of the three species that invade homes. All cockroaches share the same basic build — a flat, oval body, six legs, and long, thread-like antennae — but size and color separate the German, American, and Oriental cockroach at a glance. Below, each species gets its own section, and there is a side-by-side comparison you can scan in seconds. If you also want to rule out a lookalike or find the nest, start at our cockroaches hub.
One general clue matters no matter the species: cockroaches are nocturnal and hide during the day, so seeing one out in the open in daylight often signals a heavy population rather than a lone stray. Their flat bodies let them squeeze into the narrowest cracks, which is why an infestation can build quietly before you spot the first roach.
The German cockroach (Blattella germanica) is the most important indoor pest and is almost always the species found in kitchens and apartments, because it breeds faster than any other house roach. If you have a roach problem indoors, this is the most likely culprit.
It is small — about 1/2 to 5/8 inch, or roughly 13 to 16 mm long — and light brown to tan in color. Its signature feature is a pair of two dark, lengthwise stripes running down the shield behind the head. The body is flat, so it slips into the tightest cracks. A single female can produce more than 10,000 descendants in a year, which is why populations explode so quickly. To spot the purse-shaped egg capsules it carries, see our guide to cockroach eggs.
The American cockroach (Periplaneta americana) is the largest house-invading roach at about 1.5 inches. It is reddish-brown and is sometimes called a "palmetto bug." Unlike the German cockroach, it favors basements, sewers, drains, and other damp areas rather than kitchen cabinets.
The Oriental cockroach (Blatta orientalis) is dark and glossy, close to black, and prefers cool, damp places such as drains and cellars. Neither of these species truly flies: the American cockroach can glide or flutter for short distances in warm conditions, while the German cockroach does not fly at all. All of them run very fast, which is usually how they escape when you flip on a light.
Cockroaches almost never bite. The real risk is health-related, and it is significant:
Because the German cockroach drives most indoor problems, knowing what you are dealing with points you to the right fix in how to get rid of cockroaches.
Read together, size and color are the two most reliable identity signals. On size, the German cockroach is the smallest of the three at 13 to 16 mm; the American cockroach is the largest at about 1.5 inches; the Oriental cockroach sits in between. On color, tan with two dark stripes means German, plain reddish-brown means American, and a dark, glossy near-black body means Oriental.
Every species shares the same body plan: a flat, oval shape, six legs, and long antennae. That flatness is not just cosmetic — it is what lets a roach fit into the narrowest gap in a wall, cabinet, or baseboard. Younger roaches, called nymphs, look like smaller wingless versions of the adults, so a very small roach is not automatically a German cockroach. When in doubt, fall back on the Size-Color-Location check and confirm the location against the table above.