Mice vs rats: how to tell which one you have

Most people meet this problem as a noise at night or a few droppings in a cupboard, not as an animal in plain sight. That is enough to go on. If the droppings are about the size of a grain of rice and scattered along a route, you almost certainly have mice. If they are much larger, tapered and left in small groups, you have rats.

If you have seen the animal, look at the head and the tail rather than the size alone, because a young rat can be mistaken for a mouse. A mouse has a pointed snout and large ears for its head. A rat has a heavy, blunt head, small ears and a thick tail.

The answer matters because the two get in differently and behave differently around traps. A plan built for mice can fail against rats, and a drain problem will not be solved by anything placed in a kitchen. The rest of this guide takes each sign in turn, then sets out what to do tonight and when to call someone.

A grown house mouse is small: Oxford City Council gives 140–190 mm from nose to tail tip and about 15 g, and the British Pest Control Association (BPCA) puts the weight at under 25 g. A brown rat is another scale of animal, at 350–450 mm and about 300 g, and the BPCA notes that big adults often pass half a kilo.

Proportions are more reliable than size if you only caught a glimpse. On a mouse the tail is at least as long as the body, thin and lightly haired. On a brown rat the tail is thick and shorter than the body. The brown rat is the one to expect here; the BPCA describes the black rat as now rarely found in the UK.

Droppings are the best evidence you are likely to find, because they stay where they fall and you can measure them. Oxford City Council describes rat droppings as grouped, spindle-shaped and about 20 mm long, and mouse droppings as scattered, rod-shaped and 3–6 mm long. Lay a ruler next to one and photograph it without touching it. That photo is also the most useful thing you can send a pest controller.

Pay attention to the pattern as well as the size. Mice leave droppings as they go, so a line of them along the back of a cupboard or under a kitchen plinth is typical. Rats tend to leave theirs together in a few favoured spots. Colour is a poor guide, because droppings fade as they age and vary with diet.

Young rats leave smaller droppings, so a mix of sizes in one place can mean a family of rats and not two species. If you find anything between the two ranges, do not guess. Treat it as rats until someone has looked, because the risks of getting that wrong are higher.

Old droppings may be left over from a problem that ended years ago, which is common in lofts and under floors in older London houses. Fresh ones are dark and soft; old ones are dull, dry and crumble easily. Before you book anything, find out which you have.

The simplest test is the one the US Centers for Disease Control and Prevention describes: clean the area and check again. If new droppings appear, rodents are still there. Do it in the kitchen first. Wear disposable gloves, use disinfectant, bag the waste, and wash your hands afterwards. Then look again the next morning, and the morning after.

Lay a thin dusting of flour along the skirting behind a suspect cupboard if you want more proof. By morning, small prints and a fine tail line suggest mice; larger prints and a heavier drag suggest a rat. It also shows you the route, which is what a trap or a proofing job needs.

After droppings, these signs help you judge where the animals are and how many there may be. None of them proves the species alone, but together they usually point one way.

The gap each one needs is the most practical difference between them. The BPCA says a mouse needs 5 mm, about the width of a pencil's eraser end, and Oxford City Council says 6 mm. The BPCA gives 15 mm for a rat. That means a hole that would stop a rat will not stop a mouse, and any job has to be planned for the smaller animal if mice are the problem.

Rats commonly arrive from below. The BPCA notes that they often live in sewers and can get into a property where those are in disrepair, and Oxford City Council says rats can point to a drainage defect. Outside, they burrow under sheds and into banks, then follow the building line looking for a way in.

Mice tend to use low gaps around pipes, cables, air bricks and doors. They can also arrive inside boxes or laundry baskets. Once in, they run through wall cavities and floor voids, and in terraced houses and converted flats those voids can link one home to the next. That is why a problem in the flat next door can become yours, and why proofing your own kitchen alone may not end it.

Rats are generally the harder job and mice the more persistent one. Neither should be left alone. Both gnaw cables and pipes, and the BPCA links both to electrical fires and floods. Oxford City Council makes the same point about mice and cables.

On health, the BPCA says mice can spread Salmonella and Listeria through urine, droppings and bedding, which is why food preparation surfaces matter most. Rats carry the same kinds of risk, and they are also linked to leptospirosis, or Weil's disease. The NHS says that infection is rare in the UK, so a rat in the garden is no reason to panic. If you have flu-like symptoms after contact with rat urine or dirty water, see a GP and mention it.

Numbers are the other reason to act early. Brown rats can breed at about three months old, and the BPCA says a female may have 3 to 12 litters a year, with six to eight young in each. Mice also mature quickly. A problem you can count on one hand in October may not stay that way by Christmas.

These steps cost little and make any later treatment work better, because rodents go to traps and bait more readily when there is less food around.

One or two mice in a single room is a fair DIY job. Use break-back traps, baited with something like nutty chocolate or raisins, close to the droppings and at right angles to the wall, so an animal running along the skirting has to cross the trap. Keep them away from children and pets, and check them every day.

Be careful with poison, particularly in London. The BPCA says it is common knowledge in the industry that almost all house mouse populations in London are resistant to traditional rodenticides, and that amateur products are restricted. Shop-bought bait can therefore cost you weeks without solving anything, and a poisoned animal can die under the floor or be eaten by something else.

Rats are a different matter. The BPCA says most are wary of new objects and will avoid them for a period, so do not expect traps to work overnight. Call a professional straight away if you see any of these signs:

Citizens Advice says tenants are usually responsible where they caused the problem, for example by not disposing of rubbish properly. Landlords are usually responsible where the tenancy agreement says so, where the problem comes from a failure to make repairs such as fixing holes in walls, or where it makes the home unsafe, for example by making you ill.

Landlords are generally only responsible once they know, so tell yours straight away, in writing, with dates and your photos. Your council's environmental health team can give advice and may be able to require a landlord to act. You can contact the council about rats or mice even if you do not live in a council home, though private tenants may have to pay for treatment.

Leaving a rental soon? Keep the record of what was treated and when, and read our end of tenancy cleaning checklist too, because droppings left behind cupboards are the sort of thing a final inspection picks up.

Start by checking your own council, because services differ a lot. Some treat rats and mice, some charge a fee and some offer advice only, so check what yours covers and what it costs. Redbridge Council publishes a domestic fee of £200 for rats or mice over three visits for 2026/27, and it does not include proofing in that price.

Compare the same things whoever you ask: the number of visits, whether proofing is included, how soon someone can come and what happens if the problem returns. If you live in or near Ilford, our Ilford pest control page sets our prices beside the council's, line by line.

You do not need to know which rodent you have before you contact us. Tell us what you have seen and your postcode, send a photo if you can take one safely, and we confirm the treatment price, the number of visits and what is included in writing before any work is booked.

On the visit we find where the animals are active and treat the cause as well as the sighting, then give you a safety report and advice on sealing the entry points. If a drain turns out to be the source, it will need a drainage engineer as well, because treatment alone will not fix it.

Mice control starts from £99 and rat control from £109. For a 1-bed property, a single visit is £90–£120 with no guarantee, a 2-visit package is £160–£190 with a 1-month written guarantee, and a 3-visit package is £210–£230 with proofing recommendations and a 3-month written guarantee. Bigger properties cost more; our prices page has the detail.

We are based on Clements Road in Ilford, cover London, and carry public liability insurance. Our phone lines are open Monday to Saturday, 8am to 8pm. For other signs around the home, see our guide to early signs of pests.