Severe and light impurity, what is excused, and what is not impure at all

What counts as severe or light impurity, how much of each is excused on the body or clothes, and things that are not impure at all.

Physical impurity comes in two strengths: severe and light. Both need to be cleaned off before you pray, but the rules are a little different, and small, unnoticeable amounts of each are excused.

Severe impurity: examples
Category	Examples
From the human body	Feces, urine, semen, menstrual and postnatal blood, vomit that fills the mouth, flowing blood, pus
From animals	Urine of animals you can't eat; feces of grazing animals; feces of chickens and ducks; the milk and eggs of animals you can't eat
Other things	Alcohol; a pig, alive or dead; the meat or skin of an animal that wasn't slaughtered properly

Light impurity: examples

The urine of animals you are allowed to eat, including a horse.
The droppings of birds you are not allowed to eat.

How much is excused
Aspect	Severe impurity	Light impurity
How much can stay on you	A little bit: about the size of a small coin if thick, or a palm-sized splash if liquid	Up to a quarter of that one part of your clothes or body: like your sleeve or your foot
What happens if it's more than that	You must clean it off before praying	You must clean it off before praying

What counts as severe (ghaliza) impurity
Category	What counts
Human bodily discharge requiring wudu or ghusl	Feces, urine, semen, pre-ejaculatory fluid, menstrual blood, postpartum blood, irregular (istihada) bleeding, vomit that fills the mouth, flowing blood, and pus
From animals	The urine of forbidden animals; the feces of all grazing animals, halal or haram; the feces of non-flying halal birds such as chickens and ducks; the semen of any animal; the milk of forbidden animals; the eggs of forbidden birds; the flowing blood and pus of any living creature
Other substances	Alcohol and intoxicating drinks; water used to wash away impurity; water used to bathe a deceased person; sweat drawn from an impure substance
The pig	Whether alive or dead
After death	Any creature with flowing blood, once dead; any body part severed from a living creature with flowing blood
Insects and reptiles	Insects born from filth (such as flies from waste); the excrement of leeches; the excrement, urine and skin of snakes
Meat, fat and skin	The meat, fat or skin of forbidden animals, and of a halal animal that dies without proper slaughter, though its skin becomes pure once tanned
Human and animal fluids	The saliva of a deceased human; the sweat and saliva of animals that are impure by default; any fluid from a blood-bearing creature's body after death

What counts as light (khafifa) impurity

The urine of halal animals.
The urine of a horse.
The feces of birds forbidden to eat.

How much of each is excused
Aspect	Severe impurity	Light impurity
Excused amount	Thick: up to the weight of a dirham (about 4.5 grams). Liquid: up to a dirham's measurement: about the size of the hollow of a palm.	Up to one-quarter of the affected part: measured against the sleeve, the hem, the foot, or whatever part actually carries it, not the whole garment or body
If it exceeds that amount	Must be removed; it is obligatory to remove any amount larger than a dirham. Below that size, removing it is recommended but not obligatory.	Must be removed if it is more than a quarter. Removal is obligatory at exactly a quarter, and merely recommended if less than a quarter.
Special note	If a thick impurity weighs less than a dirham but its area is larger than a dirham's measurement, the area is what counts, not the weight.	None

Praying with an excused amount left on the body or clothes is valid, though strongly disliked (makruh).

Situations where impurity is excused regardless of amount

Splashes the size of a needle's point, even if the total ends up more than what is normally excused.
Mud or dirty water on the road, as long as no visible sign of impurity is in it.
Splashes from water used to wash a deceased body.
A small amount of milk that falls back into the milk while milking, as long as it is removed right away.
Rat droppings mixed into flour with no visible trace of them, or baked into bread without dissolving.
Rat or cat urine, except inside a container used for drinking or eating.
Splashes onto clothes or the body from an impure substance falling into water, as long as no visible sign of impurity is in the splashes.
Lying or stepping on impure ground, or spreading a wet cloth on it, when no trace of impurity is actually found.

Things that are not impure at all

The blood of a martyr, as long as it is still on their body.
The blood of aquatic animals, such as fish.
Blood or pus from a wound or the body, as long as it is not from its natural place.This item is reproduced as printed in the source; its exact meaning is unclear and it has been flagged for review.
Blood remaining in the meat or veins of a slaughtered animal, as long as it is part of that specific cut.
Blood from the heart, liver or spleen of a slaughtered animal.
Animals without flowing blood, halal or haram, alive or dead.
Aquatic animals, alive or dead.
The skin of a slaughtered animal, halal or haram, even before tanning.
The skin of a dead animal, once it has been tanned.
The fur, muscle, hooves, horns, nails, beaks, teeth or claws of any animal except the pig, as long as no moisture or fat is on them.
A living dog or elephant.
The fangs of a snake.
Insects found inside fruit and similar produce.
The fluid from silkworms, and their eyes or stomachs.
The egg of a halal bird, even if it is rotten.
The milk of a donkey.
Saliva from a person who is asleep, whether it comes from the mouth or the stomach.
Vomit that is less than a mouthful.
Sweat from animals whose saliva is pure.
Food that has gone bad, such as spoiled meat or sweets, once it no longer gives off a bad smell.
The vapour released when impurities are burned.
The smoke of impure things when they are burned.
Impurities whose essential nature has changed.
The feces of halal birds that fly in the air.
Bat feces and urine.

Najāsah ghalīẓah (severe impurity)
Category	What counts
Human bodily discharge requiring wuḍūʾ or ghusl	Feces, urine, semen, madhy, menstrual blood, postpartum blood, istiḥāḍah bleeding, vomit filling the mouth, sāʾil (flowing) blood, and pus
From animals	The urine of forbidden animals; the feces of all grazing animals, ḥalāl or ḥarām; the feces of non-flying ḥalāl birds such as chickens and ducks; the semen of any animal; the milk of forbidden animals; the eggs of forbidden birds; the flowing blood and pus of any living creature
Other substances	Alcohol and intoxicants; water used in removing najāsah; water used to bathe a corpse; sweat drawn from an impure substance
The pig	Alive or dead
Post-mortem	Any creature with sāʾil blood, once dead; any limb severed from a living such creature
Insects and reptiles	Insects generated from filth (flies from waste, for instance); the excrement of leeches; the excrement, urine and skin of snakes
Meat, fat and skin	The meat, fat or skin of forbidden animals, and of a ḥalāl animal that dies without proper dhabḥ, its skin nonetheless becoming pure through tanning
Human and animal fluids	The saliva of a deceased human; the sweat and saliva of animals najis by default; any fluid emerging from a blood-bearing creature's body after death

Najāsah khafīfah (light impurity)

The urine of ḥalāl animals.
The urine of the horse.
The feces of birds ḥarām to eat.

The excused quantities
Aspect	Ghalīẓah	Khafīfah
Excused amount	Thick: up to the weight of a dirham (approximately 4.5 grams). Liquid: up to a dirham's measurement: roughly the area of the hollow of a palm.	Up to one-quarter of the specific affected part (the sleeve, the hem, the foot), not the garment or body as a whole
Beyond the excused amount	Removal is obligatory once the amount exceeds a dirham; below that threshold, removal is mustaḥabb rather than wājib.	Removal is obligatory once the amount exceeds a quarter, and obligatory too at exactly a quarter; below a quarter, removal is mustaḥabb only
Special case	Where a thick impurity is below a dirham in weight but its area exceeds a dirham's measurement, the measurement governs, not the weight.	No corresponding exception is given

Praying with an excused amount unremoved is valid (ṣaḥīḥ) though strongly makrūh.

Cases excused regardless of amount

Splashes the size of a needle's point, even where their aggregate exceeds the ordinarily excused amount.
Mud or dirty road-water, provided no visible trace of najāsah is discernible in it.
Splashes arising from the water used to wash a corpse.
A small quantity of milk falling back into the pail while milking, provided it is removed at once.
Rat droppings mixed into flour with no visible trace, or baked into bread without dissolving.
Rat or cat urine, except inside a vessel used for eating or drinking.
Splashes reaching clothing or the body from an impurity falling into water, provided no visible trace appears in the splashes.
Lying, stepping, or spreading a wet cloth on impure ground, where no trace of the impurity is actually found.

Things ruled not impure at all

The blood of a martyr (shahīd), so long as it remains on the body.
The blood of aquatic creatures, such as fish.
Blood or pus from a wound or the body, provided it is not from its natural place.Reproduced exactly as printed in the source; the precise scope of this item is unclear and has been flagged for review rather than resolved by paraphrase.
Blood remaining within the meat or veins of a slaughtered animal, where it is part of that specific cut.
Blood from the heart, liver or spleen of a slaughtered animal.
Creatures without flowing blood, ḥalāl or ḥarām, alive or dead.
Aquatic creatures, alive or dead.
The skin of a slaughtered animal, ḥalāl or ḥarām, even prior to tanning.
The skin of a dead animal, once tanned.
The fur, muscle, hooves, horns, nails, beaks, teeth or claws of any animal but the pig, provided no moisture or fat remains on them.
A living dog or elephant.
The fangs of a snake.
Insects found inside fruit and the like.
The fluid of silkworms, and their eyes or stomachs.
The egg of a ḥalāl bird, even where rotten.
The milk of a donkey.
Saliva from a sleeping person, whether from the mouth or the stomach.
Vomit amounting to less than a mouthful.
Sweat from animals whose saliva is pure.
Spoiled food, meat or sweets, once it no longer emits an offensive smell.
The vapour released when impurities are burned.
The smoke of impure matter when burned.
Impurities whose essential nature (ʿayn) has changed.
The feces of ḥalāl birds in flight.
Bat feces and urine.