Clean and standardize phone numbers in a spreadsheet
A contact list built up over time rarely has phone numbers in one format — some with country codes, some without, some with dashes, some with spaces. DataMadeClean reads the convention your column already mostly uses and brings the rest of it into line, for your region rather than a fixed one.
No account needed · CSV and XLSX · national & international formats
Why a phone column ends up so inconsistent
Every entry point into a contact list — a form, a manual entry, an import from another system — tends to format phone numbers its own way.
- Mixed separators in the same column — dashes in some rows, spaces in others, brackets in a third
- Some rows carrying a country code and some not, in the same column
- Extra whitespace or formatting characters copied in from another system
- No consistent grouping, making the column hard to scan or validate at a glance
Before / after
The same contact list, standardized
Before
| Name | Phone |
|---|---|
| Maria O'Connell | 415.555.0128 |
| Priya Nair | +1 415 555 0186 |
| Priya Nair (second import) | 4155550186 |
After
| Name | Phone |
|---|---|
| Maria O'Connell | (415) 555-0128 |
| Priya Nair | (415) 555-0186 |
| Priya Nair (second import) | (415) 555-0186 |
Separators, spacing and country codes are all brought to the convention the column already mostly uses. The last two rows are the same contact from two systems, written two ways - once standardized, they match, which is what makes the duplicate findable.
How DataMadeClean handles it
Upload, detect, standardize
Upload your file
CSV or XLSX with a phone column — column names are auto-detected.
Format detection
The dominant format already used in your column is identified, so numbers are standardized to match it.
Standardization
Separators and spacing are made consistent, and international prefixes are normalized.
Review & download
See exactly what was standardized, then download the cleaned file.
Your file is only ever used to clean it. An anonymous upload and its result are deleted an hour after cleaning; signed in, results follow your account's retention setting.
Limitations
What standardization won't catch
- DataMadeClean checks that a number matches a recognizable format for its region — it doesn't verify the number is actually connected or reachable.
- If a spreadsheet program has already converted a long digit string to scientific notation before you upload the file, the original digits are gone and can't be reconstructed.
Phone column assembled from three systems?
Clean a file free →Questions about phone number cleaning
What does it fix in a phone column?
Inconsistent separators, spacing, and a leading zero that a spreadsheet has dropped. Numbers written three different ways come back written one way, so a column assembled from three sources reads as one. Which way is the one the column already mostly uses - see the format question below.
Will it keep the leading zero?
Yes. A phone column is treated as text rather than converted to a number, so a number beginning with a zero keeps it — and one that arrived without a leading zero has it restored where the rest of the number makes clear it belongs.
Does it handle service and freephone numbers?
Yes. Service and freephone numbers keep the grouping they are actually written with rather than being forced into a mobile number's shape.
What happens to a value that is not a valid number?
It is left exactly as it is and flagged for review. A number too short to be valid, or free text that ended up in the column, stays put and is reported rather than being guessed at or emptied — the file never comes back with a number invented in it.
What format do the cleaned numbers use?
The one the file itself mostly uses. A column of national-format numbers stays national rather than gaining a country code, and a column that already carries country codes keeps them. Your region setting decides which country a bare national number belongs to, and national or international can be fixed explicitly in your account settings.
How long is my file kept?
Anonymous uploads and their results are deleted an hour after cleaning. Signed in, results follow your account's retention period, seven days by default, and you can shorten it or delete a result yourself at any time. Read the privacy policy.
Upload your contact list and see what gets standardized.
No signup required.
Clean a file free →Get in touch if you have a question first.