Fact-checked against 1 source · Updated 3 November 2026Short answer: rats are much bigger. An adult brown rat is about 23cm long without the tail and weighs roughly 0.5kg, while an adult house mouse is about 6–9cm and under 25g. Rats also make heavier noises and rougher gnaw marks.
On this page
Quick comparison
| Sign | Rats | Mice |
|---|---|---|
| Droppings | Dark, pellet-shaped, about the size of a large grain of rice | Small, thin, roughly rice-grain size, a few millimetres |
| Body size | Adult brown rat about 23cm (range 15–28cm) without the tail, roughly 0.5kg | Adult house mouse about 6–9cm without the tail, under 25g |
| Noise | Heavy scratching, thumping, scampering | Light scratching and scurrying |
| Gnawing | Larger, rougher marks; can gnaw pipes, timber and cables | Small, fine marks on food packaging and soft materials |
| Entry gaps | About 15mm (BPCA) | Much smaller: mice can use very small gaps |
| Behaviour | Wary of new objects; follows regular runs; needs water daily | Curious; explores new objects; can live on little water |
| Where you find them | Burrows outside; lofts, wall voids, under floors | Kitchens, cupboards, wall voids, behind appliances |
Sizes and gaps are approximate and vary between animals. A technician can confirm from the evidence.
Droppings: the clearest clue
Droppings are usually the easiest way to tell rats from mice. Rat droppings are large and capsule-shaped, about the length of a grain of rice or more, and are often found in groups along regular routes. Mouse droppings are much smaller and thinner, and are scattered widely, because mice leave them as they move around. Fresh droppings are dark and soft; old ones are grey and crumble when disturbed.
Stay safe: don’t handle droppings with bare hands or sweep them up dry. Wear gloves, use damp paper towels, and wash your hands well afterwards.
Noises: heavy or light?
Rats are heavier, so they sound heavier: thumping and scampering overhead, or scratching in a wall. Mice are lighter and quicker. Their noise is more like fast, light scratching. Both are mostly active at night. See our guide to what rat noises sound like for more.
Where you find them
Rats commonly burrow outdoors, under sheds, decking and paving, and travel between the garden and the house. Indoors they favour lofts and wall voids. Mice often stay indoors in kitchens and cupboards, and can get into very small gaps. If you see burrows and runs in the garden, that points to rats.
Baby rats or adult mice?
A young rat can look like a large mouse, but has a big head, big feet and a body that looks too large for its size. An adult mouse has a smaller head and feet in proportion. If you’re unsure, treat a sighting as a warning and get it checked.
Why the difference matters
- Treatment differs. Rats need stronger bait stations and often different positioning. Mice need more traps and finer sealing.
- Proofing differs. Mice can use much smaller gaps, so proofing standards differ.
- Damage differs. Rats can gnaw pipes, cables and timber. Mice usually damage food and soft materials.
If it’s rats, see our pages on loft rat removal, garden rat control and rat proofing.
Rats or mice: common questions
Can I have rats and mice at the same time?
Yes, though rats may drive mice away from an area. A technician can identify which you have from droppings and signs.
Are rat droppings dangerous?
Rats can carry infections, so avoid touching droppings, wear gloves and a mask when cleaning, and wash your hands well. Our guide on whether rats are dangerous explains the risks.
Could it be squirrels or something else?
Possibly. Squirrels are active in daytime and noisy at dawn and dusk. Birds make light fluttering sounds near eaves. Pipes and roof timbers can also creak as they warm and cool. An inspection identifies what you actually have.
Need help now? See pest control in Newark-on-Trent, where we connect you with an independent local technician.
Droppings are often the easiest way to tell which one you have. See our guide to rat droppings and how they differ from mouse droppings.
Sources and further reading
Facts on this page were checked against the sources above on 14 October 2026. Laws, prices and council services change, so check the current position before relying on them.
This site connects households and businesses in the Newark-on-Trent area with an independent local rat-control technician. We are not the servicing contractor and do not carry out treatment ourselves. See our terms & disclosure.