Mouse Poop vs Rat Poop: How to Tell the Droppings Apart

What Is the Difference Between Mouse Poop and Rat Poop?

Mouse poop vs rat poop comes down to size first, then shape. Mouse droppings are small, thin and pointed. Rat droppings are several times longer, much thicker and usually blunt at the ends. Colour helps much less, because fresh droppings from both rodents are dark.

Here is the quick comparison:

• Mouse poop: about 1/8 to 1/4 inch (3 to 6 mm), pointed at one or both ends, about the size of a grain of rice
• Rat poop: about 1/2 to 3/4 inch (about 1.25 to 2 cm), blunt or capsule-shaped, about the size of an olive pit
• Both: dark when fresh, lighter and dry when old

If you already suspect mice and want the full picture (where droppings show up, look-alikes, how much is too much), read our complete guide to mouse poop.

Size

Size is the most reliable way to tell mouse poop from rat poop. House mouse droppings average 1/8 to 1/4 inch (3 to 6 mm) long, according to the University of Nebraska-Lincoln Extension, and Manitoba Agriculture compares them to a grain of rice. Rat droppings are much bigger: the Government of Alberta gives Norway rat droppings as about 1.25 to 1.5 cm (0.5 to 0.6 in), the size of an olive pit, and UF/IFAS gives them as about 3/4 inch (about 2 cm). Manitoba Agriculture puts the range of rat droppings at about 1.25 cm (half an inch) to 2.54 cm (1 inch).

Shape

Shape is the second clue. Mouse droppings are rod-shaped and narrow to a point at one or both ends (University of Arizona Cooperative Extension). Norway rat droppings are usually capsule-shaped and blunt at both ends, while roof rat droppings tend to be spindle-shaped, sausage-like and slightly curved (UF/IFAS, Manitoba Agriculture). Rat droppings are also much thicker: the University of Arkansas Extension describes them as up to about 1/4 inch in diameter, close to the full length of a mouse dropping.

Colour

Colour cannot tell a mouse from a rat, but it tells you how recent the droppings are. Fresh droppings from both rodents are black, shiny and soft like putty, while old ones usually turn grey or lighter brown, look dusty and crumble (UF/IFAS, Manitoba Agriculture). Diet can also change the colour, so a brownish dropping is not always old. Fresh droppings near food mean the rodents are still active. Our mouse poop guide explains how to check whether they are fresh.

How Do You Tell Rat Droppings vs Mouse Droppings Apart Without Measuring?

Rat droppings vs mouse droppings can also be told apart by how many there are, how they are spread out and where you find them. These clues help when the droppings are crushed, mixed with debris or hard to see.

Number of Droppings

The number of droppings points to mice when you find lots of tiny pellets. A single house mouse leaves about 50 to 75 droppings a day as it explores, according to the University of Nebraska-Lincoln Extension. Rats leave fewer but much larger droppings, although a single rat may produce up to about 25,000 droppings a year, according to the Government of Alberta. Dozens of rice-sized pellets in one cupboard usually mean mice, not a rat.

How the Droppings Are Spread Out

The way droppings are spread out is another clue. Mouse droppings usually do not collect in piles: mice tend to leave them scattered along their routes, in drawers and along baseboards (University of Nebraska-Lincoln Extension). Victor, a trap manufacturer, notes that Norway rat droppings tend to be found in small groups, while roof rat droppings are often more scattered. Keep in mind that rodents of both kinds often have favourite toilet spots but can leave droppings almost anywhere (UF/IFAS).

Where You Find Them

Where you find the droppings narrows down the culprit. The University of Arkansas Extension notes that roof rats tend to live on upper floors, while Norway rats usually stay on the ground floor and in basements. According to UC IPM, Norway rats often burrow along foundations and under woodpiles, and roof rats tend to nest in attics, wall voids and cabinets. Mice can turn up anywhere food is close: kitchen cupboards, pantries, under the sink and in stored boxes.

Other Signs Nearby

Other signs nearby can confirm what the droppings suggest. Rat gnaw marks are usually about 4 mm wide, while mice leave scratchy marks about 2 mm wide (UC IPM). Rat holes are usually 2 inches (about 5 cm) or larger, and mouse holes are often 1.5 inches (about 4 cm) or less, according to the University of Arkansas Extension, which also notes that a musty odour can be a sign of house mice. For the full comparison of the animals themselves, see how to tell a mouse from a rat.

Cockroach Droppings

Cockroach droppings are sometimes mistaken for mouse poop. They are usually smaller, at about 1/8 to 1/4 inch long, and under a magnifying glass they tend to show ridges along their length and squared-off ends, while mouse droppings are smooth with tapered or rounded ends (University of Arkansas Extension). If the specks are mostly in cracks, behind appliances or in cabinet hinges, check for the signs of a cockroach infestation.

What Does Rat Poop Look Like?

Rat poop is dark, usually about 1/2 to 3/4 inch long and much thicker than mouse poop, but its exact shape depends on the species. Two rats live in Canadian homes: the Norway rat (also called the brown rat or sewer rat), found in most inhabited regions of the country, and the roof rat (also called the black rat or ship rat), historically reported mainly on the BC coast.

Norway Rat Poop

Norway rat poop is the classic large rat dropping. It is usually about 3/4 inch (about 2 cm) long, capsule-shaped and blunt at both ends (UF/IFAS). The Government of Alberta describes it as shiny black, about the shape and size of an olive pit, at roughly 1.25 to 1.5 cm (0.5 to 0.6 in). You usually find it at ground level: in basements, garages, along foundations and near garbage or pet food.

Roof Rat Poop

Roof rat poop is smaller and pointier than Norway rat poop. It is usually up to 1/2 inch (about 1.3 cm) long, spindle-shaped and often slightly curved, with pointed ends (UF/IFAS). Its pointed shape can make it look like an oversized mouse dropping. If you find pointed droppings that are clearly longer than a grain of rice in an attic or on an upper floor, especially in coastal BC, consider roof rats.

Young Rat Poop

Young rat poop can sometimes be close to mouse size, according to pest control companies, which is the main trap in this comparison. Young rats leave smaller droppings, so look at the other clues: a few large droppings mixed in with small ones, gnaw marks wider than a mouse's, or holes larger than a mouse would need. Getting this right matters, because small young rats sometimes do not trigger a rat snap trap (UC IPM).

Is Rat Poop More Dangerous Than Mouse Poop?

Rat poop and mouse poop are both a health risk: the University of Kentucky notes that mice can transmit salmonellosis (bacterial food poisoning) through contaminated food, and both rodents may also carry the bacteria that cause leptospirosis. Neither is safe to touch or sweep up. The difference in Canada is mostly about which animal left the droppings, not their size.

Diseases in Droppings

Diseases spread through rodent droppings, urine and hair can include salmonellosis and leptospirosis, according to the University of Arkansas Extension, and NC State Extension notes that saliva and urine can also spread disease. UF/IFAS notes that rats can carry several different kinds of diseases and contaminate food with their urine, droppings and hair. UC IPM lists leptospirosis, salmonella and lymphocytic choriomeningitis (LCM) for house mice, and the University of Kentucky notes that mice can transmit salmonellosis through contaminated food. Manitoba Agriculture warns that breathing in dust from droppings or touching them can cause infection, and the Public Health Agency of Canada describes the same routes for hantavirus.

Hantavirus in Canada

Hantavirus in Canada has been found only in wild mice, specifically the deer mouse, according to HealthLinkBC. House mice, roof rats and Norway rats are not known to spread it. The catch is that deer mouse droppings look almost the same as house mouse droppings, so you cannot rule out hantavirus from the poop alone. Deer mice have a white belly, white feet and a tail that is white underneath (Health Canada) and are more likely in cottages, sheds and garages near fields or woods. The Public Health Agency of Canada notes that there is no vaccine for hantavirus, and infections can be fatal, so treat every cleanup with care.

Safe Cleanup

Safe cleanup is the same for mouse and rat droppings. Follow these steps from the Public Health Agency of Canada, Health Canada and the Government of Alberta:

1. Open doors and windows and let an enclosed space air out, usually for about 30 minutes, before you start.
2. Put on rubber or plastic gloves, and an N95 respirator in a confined space such as a shed or crawl space.
3. Never sweep or vacuum dry droppings, because this puts particles in the air.
4. Spray the droppings with a Health Canada-approved disinfectant or 1 part bleach to 9 parts water until soaked, and wait 10 minutes.
5. Wipe them up with paper towels and seal everything in a double plastic bag for the garbage.
6. Wash your gloves before taking them off, then wash your hands with soap and water.

Our step-by-step guide on how to clean mouse droppings covers attics, insulation and fabrics.

What Should You Do After Identifying Mouse or Rat Poop?

Identifying mouse or rat poop tells you which traps, baits and repairs to use, because mice and rats react very differently to them. Start with the steps for your rodent, then seal the gaps they use.

If the Droppings Are From Mice

If the droppings are from mice, traps are usually the fastest fix, because house mice readily try new foods (University of Arkansas Extension). Health Canada recommends snap or electronic traps placed along walls, left baited but unset for 3 to 4 days so the mice get used to them, then checked daily. Our guides on how to set a mouse trap and the best mouse traps walk you through it. Mice can live off a few crumbs, so cleaning alone will not solve the problem.

If the Droppings Are From Rats

If the droppings are from rats, expect a slower job. Rats tend to detect and avoid new objects such as traps and bait (University of Arkansas Extension), so the unset warm-up period matters even more. Use traps labelled for rats. If you use poison bait, the Government of British Columbia advises using only domestic-class products in tamper-proof bait stations, placed where children and pets cannot reach them, and the label should show a PCP number. Homeowner rodenticides containing second-generation anticoagulants (brodifacoum, bromadiolone and difethialone) are generally not sold for domestic use in Canada, and the Government of British Columbia restricts their sale and use.

Sealing Entry Points

Sealing entry points keeps both rodents out once they are gone. Health Canada notes that mice can squeeze through a crack the size of a dime and rats through a hole the size of a quarter, and UC IPM recommends sealing any hole larger than 1/4 inch to keep out both. Learn how to find and seal mouse entry points, and browse the mice hub for prevention guides.

Rat Droppings in Alberta

Rat droppings in Alberta deserve a phone call, because the province has kept a rat-free status through its Rat Control Program, reportedly since 1950. According to the Government of Alberta, many reported "rats" turn out to be other rodents such as muskrats, mice, voles or pocket gophers. If you find rat-size droppings or see a rat, take a picture, note the location and call 310-FARM (3276) toll free.

When to Call a Pest Control Professional

Calling a pest control professional makes sense if you have confirmed rats, if droppings keep appearing after a few weeks of trapping, or if there is a large amount of droppings in an attic, crawl space or insulation. Health Canada notes that commercial class rodenticides must be applied by a certified professional. Read about the signs that you need a mouse exterminator, or get a quote from a recommended local exterminator through Pest Agent's referral form.