Didn't find any accurate one so just sat down and figured out the chords...
In the orginal key and  a half step down (easier to play).

Standard tuning:
Verse + Chorus: F# Abm Ebm B
Bridge: B Ebm C# B Ebm C# B Ebm C# Abm

or tuned half step down (Eb Ab C# F# Bb Eb):
Verse + Chorus: G Am Em C
Bridge: C Em D C Em D C Em D Am

Verse 1:
                F#
If I were a boy
Abm                     Ebm    B
     Even just for a day
     F#
I'd roll outta bed in the morning
      Abm                       Ebm  B
And throw on what I wanted and go
                        F#
Drink beer with the guys
Abm                    Ebm    B
    And chase after girls
     F#
I'd kick it with who I wanted
         Abm                      Ebm
And I'd never get confronted for it
               B
Cause they'd stick up for me

Chorus:

             F#
If I were a boy
Abm                         Ebm  B
    I think I could understand
         F#
How it feels to love a girl
       Abm                Ebm  B
I swear I'd be a better man
               F#
I'd listen to her
Abm                        Ebm  B
    Cause I know how it hurts
          F#
When you lose the one you wanted
            Abm
Cause he's taken you for granted
      Ebm                         B
And everything you had got destroyed

Verse 2:
If I were a boy
I would turn off my phone
Tell everyone it's broken
So they'd think that I was sleepin' alone
I'd put myself first
And make the rules as I go
Cause I know that she'd be faithful
Waitin' for me to come home (to come home)

Chorus:
If I were a boy
I think I could understand
How it feels to love a girl
I swear I'd be a better man
I'd listen to her
Cause I know how it hurts
When you lose the one you wanted
Cause he's taken you for granted
And everything you had got destroyed

Bridge:
B                    Ebm       C#            B
  It's a little too late for you to come back
                  Ebm
Say it's just a mistake
           C#                  B
Think I'd forgive you like that
                Ebm              C#m
If you thought I would wait for you
         Abm
You thought wrong

Verse 3:
But you're just a boy
You don't understand
Yeah you don't understand
How it feels to love a girl someday
You wish you were a better man
You don't listen to her
You don't care how it hurts
Until you lose the one you wanted
Cause you've taken her for granted
And everything you have got destroyed
But you're just a boy

Hope you like it