Grammar fix
flatten out
become relatively steady
To become flatter or more stable after rising or falling.
phrasal verb
How oftenCommon
LevelB2
Used inSpeech & writing
Hear it in context
Notice where the phrase sounds natural.
After a busy spring, sales flattened out over the summer.
My progress in speaking flattened out for a few months, so I started recording myself to see what I needed to improve.
Fix the pattern
One small grammar move makes it sound right.
Not: Sales have flattened down this year.
Say: Sales have flattened out this year.
For a trend that stops rising or falling, the particle is 'out', not 'down'.
Don't confuse it
Other ways to say it
Stop rising or falling
How formalConversationalMore analytical
flatten outYou're here · A rising or falling trend becomes relatively flat.
level offPrices, numbers, or activity become steady after changing.plateauGrowth or improvement stops at a particular level.