The phrasal verbs turn down and turn up are opposites in several ways. While most people know them for volume or temperature, they also have very common "idiomatic" meanings used in daily life and business.
1. Adjusting Levels (Volume, Heat, Light)
This is the most literal use. You are increasing or decreasing the intensity of something.
Turn down: To decrease.
"It's too loud in here; can you turn down the music?"
"The oven is too hot; turn it down to 180°C."
Turn up: To increase.
"I can't hear the news; please turn up the volume."
"It’s freezing! Let's turn up the heat."
2. Accepting vs. Rejecting (The "Social" Meaning)
In a professional or social context, these words describe how we respond to offers or invitations.
Turn down: To reject or refuse an offer, invitation, or application.
"She turned down the job offer because the salary was too low."
"I had to turn down his invitation to the party."
Turn up: This doesn't mean "to accept." Instead, it means to arrive or appear (often unexpectedly).
"He didn't say he was coming, but he turned up at my door at midnight."
"Don't worry about the lost keys; they usually turn up eventually."
3. Summary Table
| Context | Turn Down | Turn Up |
|---|---|---|
| Physical/Technical | Decrease (volume, heat). | Increase (volume, heat). |
| Opportunities | Reject/Refuse. | N/A (Use "Accept") |
| Presence/Location | N/A | Arrive or be found. |
| Business/Economy | A "downturn" (decline). | An "upturn" (improvement). |
Common Expressions
"Turn down the noise": Not just volume, but a request for someone to be quieter.
"Something will turn up": A phrase used to express hope that a new opportunity or solution will appear soon.
"A turned-down collar": A specific style of shirt.
A Note on Word Order
Both of these are separable phrasal verbs when used for volume/heat. This means you can put the noun in the middle:
"Turn the radio down." (Correct)
"Turn down the radio." (Correct)
However, when "turn down" means "to reject," we usually keep it together unless using a pronoun:
"I turned down the job." (Correct)
"I turned it down." (Correct)