Bread is sliced from a loaf, so it is called a “slice” of bread. There is no “loaf” of toast, so it is a “piece” of toast.
   
“Last post made me wonder… why is it a SLICE of bread until you toast it? Then it becomes a PIECE of toast (not a slice)” was posted on Twitter by DaveRoseMcCall on December 2, 2008. “Why is it a ‘slice’ of bread but a ‘piece’ of toast? They’re the same thing, right? Only one is burnt beyond recognition…” was posted on Twitter by Angela Kohler on November 11, 2011. “Ever notice how a ‘slice’ of bread turns into a ‘piece’ of toast? Why no slices of toast, huh?” was posted on Twitter by Moon on December 1, 2011.
   
“Why is it called a ‘slice’ of bread before you put it in the toaster, but a ‘piece’ of toast when you take it out..?” was posted on Twitter by Cody Millett on October 4, 2012. “Bread goes into the toaster as a ‘slice,’ but comes out as a ‘piece’” was posted on Reddit—Showerthoughts on January 15, 2021.
   
       
Twitter 
DaveRoseMcCall
@davemccall
Last post made me wonder… why is it a SLICE of bread until you toast it? Then it becomes a PIECE of toast (not a slice).
8:59 AM · Dec 2, 2008·Twitter Web Client
   
Twitter
Angela Kohler
@angelakohler
Why is it a “slice” of bread but a “piece” of toast? They’re the same thing, right? Only one is burnt beyond recognition…
4:55 PM · Nov 11, 2011·Echofon
   
Twitter
Moon
@mooner_man
Ever notice how a “slice” of bread turns into a “piece” of toast? Why no slices of toast, huh?
8:55 PM · Dec 1, 2011·Twitter for iPhone
   
Twitter
Marsheila Rockwell the ✍🏼 Word Witch
@MarcyRockwell
How come we call it “a slice of bread,” but once we toast it, it becomes “a piece of toast?” Anyone? Bueller?
1:56 AM · Sep 20, 2012·Twitter Web Client
   
Twitter
Cody Millett
@CodyMillett
Why is it called a “slice” of bread before you put it in the toaster, but a “piece” of toast when you take it out..?
6:34 AM · Oct 4, 2012·Mobile Web
   
Twitter
Ashley Kopacki
@AshleyKopacki
Why is it called a ‘piece’ of toast but a ‘slice’ of bread?
9:07 AM · Nov 5, 2012 from Hamden, CT·Twitter for Android
     
Twitter
T.J.🕉Yin yang
@Bass_Cleffff
techonlogy: Why is it a slice of bread but a piece of toast? What changes in the bowels of that terrible… http://tmblr.co/ZXmzjo1i_Kkp8
1:09 PM · Apr 21, 2015·Tumblr
 
Twitter
andrew
@andpheat
it’s a SLICE of bread, but a PIECE of toast #whataworld
2:00 PM · Apr 7, 2013·Twitter Web Client
   
Twitter
Zoë
@ZoShelton
Why is it a slice of bread but a piece of toast?
1:39 PM · Aug 8, 2013·Twitter Web Client
   
Twitter
_ira
@kiralynnie
Why is it a slice of bread but a piece of toast?
7:48 PM · Jan 26, 2014·Twitter for Android
 
Twitter
snowph
@hobbitzilla
Why is it ‘a slice of bread’ but ‘a piece of toast’? You wouldn’t say of piece of bread now would you? #sophieasksthebigquestions
9:53 AM · Mar 17, 2014·Twitter Web Client
     
Twitter 
Sonia Vaswani
@SoniaV23
Why is it a piece of toast yet a slice of bread ?
10:44 PM · Jul 24, 2015·Twitter for iPhone
   
Twitter
Erin Newton
@ErinNewton_
Why is it a ‘slice of bread’ but a ‘piece of toast’?
6:08 PM · Dec 22, 2015·Twitter for iPhone
   
Twitter
Dupee
@lexi_dupee_18
Why is it a slice of bread but a piece of toast?
10:13 AM · Jan 12, 2017·Twitter for iPhone
 
Twitter
Spoogie
@mr_spooger
why is it called a slice of bread but a piece of toast
8:59 PM · May 10, 2017·Twitter Web Client
   
Twitter
Definitely a Chicken
@spoonythebard_
so why is it a ‘slice’ of bread… but .. a ‘piece’ of toast…
12:43 AM · Jun 19, 2017·Twitter for iPhone
   
Twitter
Brian Clark
@B_Clark255
How come we call it a slice of bread but a piece of toast
3:58 PM · Apr 19, 2018·Twitter for Android
   
Twitter
brit
@britweisman
Isn’t it really weird that it’s a “slice of bread” but then it’s a “PIECE of toast”? Like why does slice of toast feel insane to say
3:27 AM · Sep 14, 2018·Twitter for Android
   
Twitter
inndyanna
@stickyziggy
Why is it a slice of bread but a piece of toast?
5:12 PM · Apr 25, 2019·Twitter for iPhone
   
Twitter
Thomas Winegarden
@Winegarden_Thom
Wait so it is a “slice” of bread but then if you toast it, it becomes a “piece” of toast? #bread
3:13 PM · Dec 19, 2019·Twitter for iPhone
 
Twitter
Rae Aragorn
@AragornErso
Why is it a “slice of bread” but a “piece of toast”?
#Questionbox #questiontime #wondering
8:37 PM · Apr 26, 2020·Twitter for Android
 
Reddit—Showerthoughts
Posted by u/gabriele208 January 15, 2021
Bread goes into the toaster as a “slice,” but comes out as a “piece.”
 
Twitter
Jacob Maier
@ChuckleFunky
It’s amazing how heat can turn a *slice* of bread to a *piece* of toast.
I don’t know. Maybe it’s the Quaaludes.
9:56 AM · Jan 16, 2021·Twitter Web App