A simile is a figure of speech in which two unlike things are explicitly compared. Although similes and metaphors are sometimes considered to be interchangeable, similes acknowledge the imperfections and limitations of the comparative relationship to a greater extent than metaphors.
To help you identify a simile versus a metaphor, know that the words “like” or “as” are typically used in a simile.

This is a list of well-known as...as similes

As blind as a bat = unable to see well

As bald as a coot = completely bald

As brown as a berry = entirely or very brown; often referring to a suntanned skin

As busy as a bee = to be moving about quickly doing many things

As cold as a fish = unemotional

As cold as any stone = very cold

As clean as a whistle = extremely clean

As clear as mud = ironic, meaning not clear at all; very difficult to understand

As cool as a cucumber = very calm or very calmly, especially when this is surprising

As dead as a doornail = dead, devoid of life, unusable

As delicate as a flower = fragile

As easy as ABC = very simple

As easy as pie = very easy

As fit as a butcher's dog = very fit and healthy

As fit as a fiddle = very healthy

As flat as a pancake = very flat and level

As free as a bird = free to go anywhere

As fresh as a daisy = clean and fresh/ to be full of energy and enthusiasm

As gentle as a lamb = very gentle

As happy as a dog with two tails = very happy

As happy as Larry = very happy

As happy as a sandboy = very happy and content

As hard/ tough as nails = a person who is very tough, strong and very determined

As helpless as a baby = absolutely helpless

As keen as mustard = very enthusiastic

As good as gold = very good/(of a child) to behave very well

As light as a feather = light in weight

As mad as a March hare = extremely silly or stupid

As mad as a wet hen = completely mad

As nice as ninepence = neat, tidy, well-ordered

As old as Methuselah = very old

As old as the hills = exceedingly old

As plain as day = clear to see

As plain as the nose on your face = to be very obvious

As pleased as Punch = very pleased

As poor as a church mouse = extremely poor

As proud as a peacock = very proud

As pure as driven snow = entirely pure, innocent/ to be morally completely good

As quiet as a mouse = very quiet

As quick as a wink = happens in a short amount of time

As rare as hens' teeth = extremely rare

As red as a beetroot = to have a red face because you are embarrassed

As regular as clockwork = never late or always at the same time

As right as rain = to feel healthy or well again

As safe as the Bank of England = strong and secure

As sick as a dog = very sick /vomiting a lot

As silent as the grave = to say absolutely nothing

As silly as a goose = very foolish

As slow as molasses = moves very slowly

As slippery as a fish = a person who is not trustworthy

As slippery as an eel = a person who is not trustworthy

As sly as a fox = a person who is clever and tricky

As small as the hairs on a gnat's bullock = tiny, very small

As smooth as silk = very smooth

As smooth as a baby's bottom = extremely smooth

As snug as a bug in a rug = comfortable and warm

As sober as a judge = to not be at all drunk

As sound as a bell = to be very healthy or in very good condition

As straight as an arrow  =very straight

As strong as an ox  = very strong

As stubborn as a mule  = very obstinate

As sturdy as an oak tree  = very strong

As sweet as honey  = very sweet

As tall as a tree = very tall

As thick as a brick = not very smart

As ugly as sin  = very guilty, miserable, or ugly

As white as a ghost  = pure white

As white as snow  = pure white

As wise as an owl = very wise