In 15 Seconds
- Write information into the blank spaces of a form.
- Update someone with information they missed or don't know.
- Substitute for a person who is absent from work.
Meaning
To write information in the empty spaces of a document or form, or to provide missing details to someone.
Key Examples
3 of 6At a doctor's office
Please fill in your name and address on this form.
Please fill in your name and address on this form.
Missing a meeting
I missed the start; can you fill me in?
I missed the start; can you fill me in?
Texting a friend about gossip
Wait, what happened with Sarah? Fill me in!
Wait, what happened with Sarah? Fill me in!
Cultural Background
Americans often use 'fill out' for an entire form and 'fill in' for a specific line. Using 'fill in' for a whole form is understood but sounds slightly British. 'Fill in' is the standard term for both specific lines and entire documents. It is ubiquitous in British bureaucracy. In many English-speaking offices, 'filling someone in' is a key part of 'onboarding' or 'handover' processes. It is seen as a sign of a good teammate. On platforms like TikTok or Instagram, creators often say 'Let me fill you in' before sharing a story or 'storytime' video.
Pronoun Rule
Always put 'it', 'me', or 'them' in the middle: 'Fill it in.'
Not for Liquids
Never say 'fill in a glass.' Use 'fill' or 'fill up.'
In 15 Seconds
- Write information into the blank spaces of a form.
- Update someone with information they missed or don't know.
- Substitute for a person who is absent from work.
What It Means
Think of fill in as completing a puzzle. You have a blank space, and you put something there. Usually, it is about writing your name or address on a form. It can also mean giving someone information they missed. If you missed a meeting, your friend might fill you in on the details. It is about making something complete that was empty before.
How To Use It
You can use fill in with objects like forms or blanks. You can also use it with people. For documents, say fill in the form. For people, say fill me in. Notice that you can split the phrase. You can say fill in the blanks or fill the blanks in. Both are perfectly fine. It is a very flexible phrase for daily life.
When To Use It
Use this at the doctor's office when they give you paperwork. Use it at a new job during orientation. It is great for school tests with fill-in-the-blank questions. You can also use it socially. If you arrive late to a movie, ask your friend to fill you in on the plot. It works whenever information is missing.
When NOT To Use It
Do not use fill in for physical containers like a glass of water. For a glass, you just say fill. You would not fill in a bucket with sand. That sounds like you are writing on the sand! Also, avoid it in very high-level legal contracts. In those cases, lawyers might prefer complete or execute. But for 99% of life, fill in is your best friend.
Cultural Background
In Western culture, paperwork is everywhere. From opening a bank account to joining a gym, you are always asked to fill in something. It reflects a society that loves records and data. There is also a cultural value on being 'in the loop'. If you are not filled in, you feel left out of the group. It is about connection and shared knowledge.
Common Variations
You might hear fill out instead of fill in. In the US, people often say fill out a form. In the UK, fill in is more common. They mean the exact same thing for documents. Another variation is fill in for someone. This means doing their job while they are away. If your coworker is sick, you fill in for them. It is like being a substitute.
Usage Notes
The phrase is very versatile and fits almost any situation from a hospital to a coffee shop. Just remember that 'fill in' is for information, while 'fill' is for physical objects.
Pronoun Rule
Always put 'it', 'me', or 'them' in the middle: 'Fill it in.'
Not for Liquids
Never say 'fill in a glass.' Use 'fill' or 'fill up.'
Professionalism
In an interview, say 'I'm happy to fill you in on my previous experience.'
Politeness
If you join a group late, say 'Sorry I'm late, can someone fill me in?'
Examples
6Please fill in your name and address on this form.
Please fill in your name and address on this form.
Standard use for completing paperwork.
I missed the start; can you fill me in?
I missed the start; can you fill me in?
Asking for an update on what happened.
Wait, what happened with Sarah? Fill me in!
Wait, what happened with Sarah? Fill me in!
Informal way to ask for the latest news.
I accidentally filled in the 'Tip' section with my phone number!
I accidentally filled in the 'Tip' section with my phone number!
Using the phrase to describe a silly error.
You don't have to tell me everything now, but fill me in when you're ready.
You don't have to tell me everything now, but fill me in when you're ready.
Showing patience and willingness to listen.
Can you fill in for Mark while he is on leave?
Can you fill in for Mark while he is on leave?
Using the phrase to mean 'substitute'.
Test Yourself
Complete the sentence with the correct form of 'fill in' and the pronoun 'it'.
I have the application form here. Please ________.
When using a pronoun like 'it', it must go between 'fill' and 'in'.
Which sentence uses 'fill in' to mean 'substitute'?
Choose the correct option:
'Fill in for [someone]' is the pattern for substitution.
Match the 'fill in' sentence to its meaning.
1. Fill in the form. 2. Fill me in. 3. Fill in for her.
1 matches B (document), 2 matches C (news), 3 matches A (substitute).
Complete the dialogue.
A: I missed the meeting. What happened? B: Don't worry, I'll ________ on the details.
To update a person, we say 'fill [person] in'.
🎉 Score: /4
Visual Learning Aids
Practice Bank
4 exercisesI have the application form here. Please ________.
When using a pronoun like 'it', it must go between 'fill' and 'in'.
Choose the correct option:
'Fill in for [someone]' is the pattern for substitution.
Match each item on the left with its pair on the right:
1 matches B (document), 2 matches C (news), 3 matches A (substitute).
A: I missed the meeting. What happened? B: Don't worry, I'll ________ on the details.
To update a person, we say 'fill [person] in'.
🎉 Score: /4
Frequently Asked Questions
10 questionsBoth are correct. Use 'fill in' for specific blanks and 'fill out' for entire forms (especially in the US).
No, you must say 'fill me in.' The pronoun always goes in the middle.
Yes, but 'fill in' is more casual and implies giving missing details rather than a formal announcement.
Yes, that is the literal meaning. 'I filled in the crack in the wall with plaster.'
Use 'on'. Example: 'Fill me in on the news.'
Yes, a 'fill-in' is a person who substitutes for another, like a 'fill-in teacher.'
No, you 'fill in for a person' or 'fill in at a place.'
It's better to use 'completed' or 'provided' on a resume for a more professional tone.
There isn't a direct opposite phrasal verb, but you might say 'leave blank.'
Yes, it is very common for websites and apps.
Related Phrases
fill out
similarTo complete a whole form.
fill up
contrastTo make a container full of liquid/gas.
stand in
synonymTo substitute for someone.
clue in
similarTo give someone information.
complete
synonymTo finish something.
