Confused about using 'what for' vs 'why' in everyday conversations
I’ve been watching some English shows and noticed people sometimes say "what for" instead of just asking "why." For example, in one scene a character said, "I need your help." The other replied, "What for?" But I thought you would just say "Why?" in that situation.
Are there any rules about when to use "what for" instead of "why"? I’m writing a dialogue for my class, and I’m wondering if it sounds natural to ask, "Why are you leaving?" versus "What are you leaving for?" or even just, "What for?" I don’t want my sentences to sound awkward. Any help would be appreciated!
Context:
American English, informal conversations
What to Know
| What to Know | Why It Matters | Example | Quick Check |
|---|---|---|---|
| Use "why" to ask about the reason behind an action: Why are you leaving? | If your sentence sounds awkward, check if you’re aiming for cause or purpose! | This wording is correct because it matches the intended meaning in context. | Can I explain why this form fits this sentence better than the alternative? |
| Writers often memorize a definition but miss the context cue that controls the correct choice. | This helps you choose wording by meaning instead of surface form. | A different phrasing is better when the literal meaning would be clearer. | Did I choose this form for meaning, not because it looked familiar? |
3 Answers
Great question! In informal American English, both "why" and "what for" are used to ask about reasons or purposes, but their usage patterns differ:
Patterns:
- Use "why" to ask about the reason behind an action: Why are you leaving? (You're seeking the cause.)
- Use "what for" to ask about the purpose or intended result: What are you leaving for? (You're asking about the goal or outcome.)
- In informal speech, "What for?" is often a quick way to ask for purpose after a request (e.g., “I need your help.” – “What for?”).
Contrast:
- A: "I'm buying a new laptop."
- B: "Why?" (What is the reason?)
- B: "What for?" (What will you do with it?)
Practice:
Try rephrasing these sentences with both "why" and "what for" to see how the meaning shifts:
- "I'm calling you."
- "She's taking the bus."
Feedback Tip:
When in doubt in dialogue, use "why" for reasons and quick "What for?" as a response to a suggestion or request. If your sentence sounds awkward, check if you’re aiming for cause or purpose!
Native speakers pick between "why" and "what for" based on formality and focus:
- Use "why" for a general cause: "Why did you quit your job?"
- Use "what for" for an intended usage: "I bought this tool." — "What for?" (What do you plan to use it for?)
Tip: After someone asks a favor or states an intention, "What for?" is a natural, snappy reply.
Contrast in context:
Person A: "I’m getting up early tomorrow."
- Person B: "Why?" (Looking for the reason—maybe an early appointment.)
Person A: "Can you bring your car?"
- Person B: "What for?" (Wants to know the purpose—maybe to carry something.)
Practice:
Pair up intentions and responses in your script, trying “Why?” vs. “What for?” See which sounds direct and which implies curiosity about the plan.
Edit Check:
Read your dialogue aloud and notice if "what for?" after a request sounds more natural and brief, but use "why" when you need more detail.
To decide between "why" and "what for," compare their typical use:
- Why asks about cause or motive (what made someone do something).
- What for asks about purpose or goal (what someone wants to achieve).
Example 1:
A: "I'm skipping the meeting."
B (using why): "Why?" (You want the reason — maybe they don’t feel well.)
B (using what for): "What for?" (This sounds a bit odd because it’s not the usual pattern; it can work, but is less natural here.)
Example 2:
A: "Can you give me a ride?"
B: "What for?" (Natural: B is asking about the reason or destination.)
Practice tip:
Write your dialogue, then swap “why” and “what for” in questions. If the sentence feels incomplete without context, you likely need “why.” If the request is obvious and you’re curious about their goal, “what for” works well.
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