If you suspect you have rodents in your house, identifying whether you're dealing with mice or rats is important since the approach to getting rid of them can be slightly different. The main differences come down to size, the droppings they leave behind, the kind of noise you hear, and the damage you see.

The single fastest identification method: find a dropping and measure it. Under 6mm = mouse. Over 12mm = rat. This single measurement tells you what pest you're dealing with and which control approach to use.

Physical Signs: Droppings and Tracks

• Mice droppings are small, only about the size of a grain of rice (3–6 millimeters long). They look like tiny black or dark brown cylinders with pointed ends.
• Rat droppings are much bigger — about the size of a raisin (12–19 millimeters long). They have rounded or blunt ends and are shiny black or dark brown.
• Tracks and footprints: Mice have tiny feet, so their footprints are very small. Rats leave much larger footprints, sometimes visible in dusty areas.
• Grease marks: Both will leave dark, greasy marks along walls and baseboards as they repeatedly rub against these areas. Rat smudges are much larger and more noticeable.

Noises and Activity

• Mice are light and their movements are quick. You might hear scratching, nibbling, or soft scurrying, especially at night or in quiet moments. These noises often come from overhead (ceilings, attics) or inside walls.
• Rats are heavier and louder. You might hear thumping, gnawing, or heavy scurrying, sometimes even during the day. The noise is deeper and often comes from under the floor or beneath appliances.

Damage and Chew Marks

• Mice chew smaller holes (about the size of a dime) in food packaging, walls, or furniture. Their teeth marks are tiny, about 1–2 millimeters wide.
• Rats create much bigger holes — closer to the size of a quarter or larger. They can gnaw right through wood, plastic, and even soft metals. Their teeth marks are wider and deeper — up to 4 millimeters wide.

Nests and Smell

• Mice build small, delicate nests out of shredded paper, fabric, or insulation. These nests are usually found in hidden locations — behind appliances, inside drawers, or inside walls.
• Rats make much larger and messier nests, often using coarse materials like sticks, plastic, and fabric, and often found in burrows under buildings or in basements and crawl spaces.
• Odor: A large mouse infestation creates a distinct, musty urine smell, but rat urine smells much stronger and more pungent. Rat infestations can leave an ammonia-like odor in an area.

Sightings: What Do They Look Like?

• Mice are small — typically 2–4 inches long (excluding the tail), with small, delicate heads, pointed noses, large ears, and long, thin tails with little hair.
• Rats are much larger — up to 9 inches (body only) with thick, blunt heads, smaller ears in proportion to their head, and thick, scaly tails. Their body looks bulkier and less agile than a mouse.

Behavior and Habitat

• Mice are curious and will explore new things in their environment. They nest closer to food sources and might be spotted out in the open more often than rats.
• Rats are very cautious, avoiding new objects and sticking to the same paths. Norway rats (the most common kind in homes) tend to stay low, under buildings or in basements, while roof rats prefer attics and upper floors.

In New Hampshire, the most common combination scenario is house mice in the kitchen and upper floor areas, with Norway rats in the basement or crawl space. It's possible to have both simultaneously — check all levels of the building, not just where you've seen activity.

If You're Still Not Sure

If you're in doubt, you can take pictures of the droppings, holes, or damage and compare them with online images. You can also set up a non-lethal trap to catch and identify the rodent. Or, if you want reassurance and targeted control, contact a local pest professional — they'll quickly tell you what you're dealing with and how best to remove it.

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