Rat Droppings vs Mouse Droppings - How to Tell the Difference

Size

Rat droppings are roughly 12 to 17mm long — comparable to an olive stone or a large grain of rice, and unmistakably substantial once you have seen one. Mouse droppings are 3 to 6mm, about the size of a grain of rice or a little smaller.

The gap between them is large enough that a single dropping usually answers the question. If you are hesitating, it is more likely to be a mouse, because a rat dropping does not leave people uncertain.

Shape

Rat droppings are tapered at one or both ends, sometimes slightly curved, and dark and shiny when fresh. Brown rat droppings are broader with blunter ends than black rat droppings, though brown rats are what you will have here.

Mouse droppings are much finer, more pointed at the ends, and often described as looking like dark grains. They dry out and crumble far more readily than rat droppings, which harden.

Distribution, Which Is the Better Test

Mice produce a great many droppings — dozens a day — scattered widely wherever they travel. Finding a scatter along a shelf, in a drawer, across the back of a cupboard and behind the units is a mouse pattern.

Rats produce fewer, larger droppings, concentrated along runs and often in latrine areas. Droppings collected in a line against a joist or a wall, or piled in one spot, is a rat pattern. Distribution tells you more than any single dropping does.

Age, and Why It Matters

Fresh droppings are dark, moist-looking and soft. Older ones are dull, grey-brown, dry and crumble when pressed with something — not with your fingers.

This matters because it separates a current problem from a historic one. A loft full of dry crumbling droppings and nothing fresh may be a record of something dealt with years ago. Clear a small area, mark it, and check in a few days: new droppings mean current activity.

Handle It Properly, and What It Changes

Do not sweep or vacuum droppings dry, which puts particles into the air. Dampen with a disinfectant solution first, pick up with gloves and a disposable cloth, bag it, and wash your hands afterwards. Ventilate a loft before working in it.

The identification changes the job: rats mean a survey of the drains and ground-level entry, at £190 for a flat or £240 for a house; mice mean the kitchen voids and the internal penetrations, at the same prices but a different search. Photograph what you find and keep a sample if you are unsure — it saves guessing on the visit.