Mouse or Rat? Here’s How to Know for Sure
Not sure whether you’re dealing with mice or rats? It’s more common than you’d think — especially if all you’ve noticed are scratching sounds or a few droppings. But getting the ID right matters. Rats and mice behave differently, enter homes differently, and often need different traps or treatment plans.
This guide will help you tell them apart by looking at the key signs: from size and droppings to behaviour and where they tend to hide.
Quick Checklist
- Droppings: Rice-grain sized and scattered = usually mice; larger (about jellybean/capsule sized) and often in groups = usually rats.
- Noise: Light, quick scratching in ceilings/walls = more often mice; heavier thuds/dragging/gnawing = more often rats.
- Where: Behind appliances/inside cupboards = more often mice; burrows under decking/sheds or activity near bins = more often rats.
- If unsure: Treat it as rats until you confirm - you'll proof more thoroughly and use correctly sized traps.
Key Differences at a Glance
| Feature | Mouse | Rat |
|---|---|---|
| Size | ~6–10cm body (excluding tail) | ~20–25cm body (excluding tail) |
| Tail | Long, thin, often about body length | Thicker, scaly; often shorter relative to body |
| Droppings | Small (about 3–6mm), rice-grain sized | Larger (often 10–20mm), capsule/jellybean sized |
| Behaviour | Curious, fast-moving, light-footed | More cautious, heavier, noisier |
| Entry gaps | Can squeeze through cracks as small as ~5mm | Can squeeze through gaps around ~25mm (about a 10p coin) |
| Most common UK “where” | Kitchens, lofts, behind appliances | Gardens/burrows, under decking/sheds, drains & bin areas |
Appearance
The most obvious giveaway is size. Adult rats are significantly larger than mice and tend to look more robust. Mice are small, quick, and tend to have large ears and a pointed nose. Rats have smaller ears in proportion to their head, and a blunt snout. Their tails also differ — a rat’s tail is thick, scaly, and shorter relative to its body.
Quick note: a juvenile rat can be mistaken for a mouse. If you’re unsure, compare feet/head size and check droppings/entry gaps. Also, shrews and voles can look mouse-like — and some species are legally protected — so avoid handling wildlife and focus on identifying the signs indoors.
Droppings
One of the clearest signs is what's left behind. Mouse droppings are tiny and pointed at both ends — often found near food sources or along walls. Rat droppings are much larger and more sausage-shaped. If you’re spotting droppings under sinks or in loft spaces, the shape and size can tell you what you’re dealing with.
Safe clean-up (important): don’t vacuum droppings. Ventilate, wear gloves, dampen droppings with disinfectant, lift with paper towel, double-bag, then disinfect surfaces and wash hands. If it’s heavy contamination (loft insulation/nesting/strong odour), pause and consider professional help.
Sounds and Movement
Think you’ve heard something scurrying? Mice make lighter, quicker sounds and often scratch or rustle behind walls or in ceilings. Rats tend to move more slowly but make louder noises — thuds, gnawing, or dragging. Their size makes them harder to miss once they’re inside.
Where Are You Seeing Activity?
Rats and mice have different habits. Mice love small indoor spaces: behind the fridge, airing cupboards, or even inside drawers. Rats are more likely to burrow under decking, tunnel along garden walls, or enter through damaged drains. If you're seeing holes near the compost heap or around sheds, rats are the more likely culprits.
Entry Points & Damage
Mice can squeeze through cracks as small as ~5mm (and councils often describe it as a pencil-width gap). Rats need bigger gaps — around ~25mm (about a 10p coin) — but they’ll also chew and enlarge weak spots around vents, pipework and damaged boards. If you notice gnawed bin lids, chewed pipes, or soil pushed away near foundations, rats could be to blame.
Why It Matters
The control methods you use depend on whether you're dealing with mice or rats. Traps, bait stations, and proofing products vary in size and strength. For example, mouse traps aren’t strong enough to deal with a rat. And the placement of bait stations changes depending on their behaviour.
- Need to control mice? See our mouse control guide
- Think it’s rats? Read our rat control guide
Final Thoughts
Telling the difference between rats and mice isn’t always obvious — but once you know what signs to look for, the picture becomes clearer. Size, droppings, behaviour, and where you’re seeing activity are all strong clues.
FAQs: Mouse or Rat?
Can a young rat look like a mouse?
Yes - use droppings size, foot size, and the "where" clues to confirm.
Are droppings the most reliable sign?
Often, yes. Mice are typically 3-6mm; rats are typically 10-20mm.
Do rats and mice use the same entry holes?
Not usually - mice can use tiny cracks; rats need larger gaps (around 10p/25mm), but can chew and widen weak points.
I can hear scratching in the walls - which is it?
Mice are usually lighter/quick; rats are heavier/noisier. Use droppings + location to confirm.
What should I do next once I know?
Follow the matching guide: mouse control vs rat control (different trap sizes + placement).
We go to great lengths to ensure that all our pest control products are effective, fast & easy for everyone. You may also find our expert mouse guide or expert rat guide useful if you want to learn more about getting rid of rodents from your home or business.
