Very simple, and quite repetitive, version of the song. C & F are strummed one after the other,
*Short pause*, then G & Am are strummed.
[Intro]
| C F | G Am | x2
[Verse]
C F G Am C F G Am
Oh, it's you, I know, you're the one I dream of
C F G Am C F G Am
Look into my eyes, take me to the clouds above
C F G Am C F G Am
Ooh, I lose control, can't seem to get enough
C F G Am C F G Am
When I wake from dreaming, tell me is it really love
[Chorus]
C F G Am
How will I know if you really love me
C F G Am
I say a prayer with every heartbeat
C F G Am
I fall in love whenever we meet
C F G Am
I'm asking you what you know about these things
C F G Am
How will I know if you're thinking of me
C F G Am
I try to phone but I'm too shy (can't speak)
C F G Am
Falling in love is all bittersweet
C F G Am
This love is strong, why do I feel weak
[Instrumental]
| C F | G Am | x2
[Verse]
C F G Am C F G Am
Oh, wake me, I'm shaking, wish I had you near me now
C F G Am C F G Am
Said there's no mistaking, what I feel is really love
[Bridge]
Em F Dm C
How will I know, How will I know,
Em F Dm G
How will I know, How will I know...
[Chorus]
C F G Am
How will I know if you really love me
C F G Am
I say a prayer with every heartbeat
C F G Am
I fall in love whenever we meet
C F G Am
I'm asking you what you know about these things
C F G Am
How will I know if you're thinking of me
C F G Am
I try to phone but I'm too shy (can't speak)
C F G Am
Falling in love is all bittersweet
C F G Am
This love is strong, why do I feel weak
Source: https://tabs.ultimate-guitar.com/tab/sam_smith/how_will_i_know_chords_1506780