How to Abbreviate "Additional"?
The most common abbreviation for "additional" is add'l. Two other accepted forms are addt'l and add. The apostrophe stands in for the letters left out, so add'l…
The most common abbreviation for "additional" is add'l. Two other accepted forms are addt'l and add. The apostrophe stands in for the letters left out, so add'l is short for ad(diti)onal. These abbreviations belong in forms, headlines, notes, and tables where space is tight, not in ordinary prose, where you should write the full word "additional". The form addnl is sometimes seen but is non-standard, so it is best avoided.
The three standard abbreviations
"Additional" has three widely accepted short forms. Each uses an apostrophe to mark the missing letters, which is the standard way English abbreviates a word from the inside rather than just cutting off the end. The table below shows all three with how they read.
Abbreviation | How it shortens "additional" | Status |
|---|---|---|
add'l | Keeps add, l; apostrophe for the middle | Most common |
addt'l | Keeps addt, l; apostrophe for the middle | Common, especially in formal fields |
add. | Keeps add with a closing period | Accepted, mostly military and brief notes |
addnl | Keeps add, n, l, no apostrophe | Non-standard, avoid |
All three of the standard forms are correct, so picking any one is grammatically fine. The choice usually comes down to the field you are writing in and the style your workplace or document follows.
Which abbreviation to use, by field?
Different industries have settled on different preferences, mostly out of habit and house style. If you are writing for a particular field, matching its convention makes your document look consistent with others in that area.
Field | Preferred form |
|---|---|
Business and finance | addt'l |
Legal | addt'l |
Government | addt'l |
Engineering and architecture | add'l |
Construction | add'l |
Mortgage and housing | add'l |
Military | add. |
General notes and headlines | add'l |
The single safest choice across most everyday writing is add'l, since it is the most widely recognized. When a field clearly prefers another form, follow that.
When you should abbreviate "additional", and when not to?
The key rule is that these are space-saving abbreviations, not substitutes for the word in normal writing. They belong where room is limited or where shorthand is expected.
Use the abbreviation | Write it in full |
|---|---|
Forms and fields with a character limit | Essays and academic papers |
Headlines and headings | Articles and blog posts |
Tables, spreadsheets, and labels | Business letters and emails to clients |
Personal notes and shorthand | Reports meant for a wide audience |
Invoices and order lines | Anything formal or published |
In short, if space is the reason, abbreviate. If a reader expects polished prose, write "additional" out in full. A sentence like "We will charge an additional fee" should never appear as "We will charge an add'l fee" in a customer-facing message, but "add'l fee" is perfectly clear on an invoice line.
How to write the abbreviation correctly?
Two small details decide whether the abbreviation looks right.
The apostrophe
In add'l and addt'l, the apostrophe replaces the omitted letters, so it sits in the middle of the word rather than at the end. Leaving it out, as in addl, produces the non-standard form. Use a straight or curly apostrophe to match the rest of your document.
The period
The form add. takes a closing period because it is a simple truncation of the word, the same way etc. or vol. do. The apostrophe forms add'l and addt'l do not need a trailing period, though you will sometimes see one in very formal writing. Be consistent within a single document.
What does "additional" mean?
"Additional" is an adjective meaning extra, added, or more than what is already present. It comes from the noun "addition" and describes something supplied on top of an existing amount, such as additional information, additional charges, or additional time. The abbreviation carries the same meaning, just in fewer characters.
Counting characters when space is the reason
Most of the time you abbreviate "additional" because a field, headline, or label has a character limit. If that is the case, it helps to see exactly how much space you save and whether the line still fits. Pasting your text into our character counter shows the character count with and without spaces in real time, so you can check a headline or a form field against its limit. The word counter is there too if you are tracking length across a whole document, and the case converter can fix the capitalization of a heading once the wording is set.
Frequently Asked Questions
What is the abbreviation for "additional"?
The most common abbreviation is add'l. Two other accepted forms are addt'l and add. All three are correct, and add'l is the most widely recognized, so it is the safest choice for general use.
Is "addl" without an apostrophe correct?
No. The standard forms use an apostrophe to mark the missing letters, as in add'l. Writing addl without the apostrophe, or addnl, is non-standard and should be avoided in careful writing.
Is it add'l or addt'l?
Both are correct. Add'l is more common in engineering, construction, and general writing, while addt'l is preferred in business, legal, and government documents. Pick the one your field or house style favours and use it consistently.
Can I use the abbreviation in an essay?
No. Abbreviations like add'l belong in forms, headlines, tables, and notes where space is limited. In an essay, an article, or any formal prose, write "additional" out in full.
Does "add." need a period?
Yes. The form add. is a truncation, so it takes a closing period, like etc. or vol. The apostrophe forms add'l and addt'l do not require a trailing period. Keep your choice consistent through the document.
Sources
The abbreviation forms and usage conventions in this guide reflect standard English abbreviation references, including Writing Explained, The Word Counter, and the Wiktionary entry for add'l, which together list add'l, addt'l, and add. as the accepted forms and note that addnl is non-standard.
