Skip to main content

10-Digit Phone Number

This column validation uses a SharePoint formula to require a phone number to be exactly 10 digits long. Applied as column validation, it checks the value the moment someone saves the item and blocks entries that do not pass.
Built with
Features
Column Validation, Single Line of Text Column
Category
Formulas

Want one like this?

Talk to Greg

How It Works

  • What it does: Requires the Phone value to be exactly 10 characters long.
  • If it passes: The phone number is 10 digits, so the item saves.
  • If it fails: SharePoint stops the save and shows your message, for example: Phone number must be exactly 10 digits.

Common Use Cases

  • Clean phone-number entry
  • Consistent contact data
  • Preventing short or long numbers
  • Dialer-ready formats

Details

  • Formula Type: Column Validation
  • Formula Category: Text & Names

Required Columns

Display nameColumn type
PhoneSingle line of text

Prerequisites

  1. Create the column the formula reads: Phone
  2. Add or edit a few items so there is data for the formula to work with

How to Apply the Formula

  1. Open the column you want to validate (Edit column, then More options)
  2. Expand Column validation
  3. Paste the formula below into the Formula box
  4. Add a user message that explains the rule, so people know why an entry was blocked
  5. Save. From now on, new or edited entries must pass the rule

Formula

=LEN([Phone])=10

Common Questions About 10-Digit Phone Number Formula

What does this formula do?

Enforce length. It runs as column validation, so it checks the value when the item is saved and blocks entries that do not pass.

Which columns do I need to set this up?

You need: Phone (Single line of text). The formula reads these to produce its result.

Will it check items that are already in the list?

No. Validation applies only to new or edited entries. Existing items are not re-checked when you add the rule.

If LookBook 365 is code-free and out-of-the-box, why does this example use a formula?

A SharePoint formula is native, declarative configuration, not custom development. It only works with the item’s own fields and simple logic – it cannot run scripts, reach external services, or change other data, and nothing is deployed to your tenant. It keeps working through Microsoft updates. If you would rather not set this up yourself, this is exactly the kind of thing I configure for clients.

10-Digit Phone Number Formula Example
10-Digit Phone Number Formula Example