Astonishing Guide to 15-digit to 18-digit ID Conversion

salesforce Apex How to convert a 15-digit record ID to an 18-digit record and vice versa?

December 7, 2025•10 min read

In Salesforce, the 15-digit ID is case-sensitive while the 18-digit ID is case-insensitive (the extra 3 characters form a checksum). Here's how to convert between them in Apex:

15-digit → 18-digit

This is straight forward since Salesforce's Id type automatically handles it:

apex

// Method 1: Direct cast
String id15 = '001D000000IqhSL';
Id id18 = (Id) id15;
System.debug(id18); // 001D000000IqhSLIAZ

// Method 2: Using String.valueOf()
String id18String = String.valueOf((Id) id15);

JavaScript

18-digit → 15-digit

Simply truncate the string to 15 characters:

apex

String id18 = '001D000000IqhSLIAZ';
String id15 = id18.substring(0, 15);
System.debug(id15); // 001D000000IqhSL

JavaScript

Utility Class Example

apex

public class IdConverter {
    
    // Convert 15-digit to 18-digit
    public static String to18Digit(String id15) {
        if (String.isBlank(id15)) return null;
        if (id15.length() == 18) return id15;
        if (id15.length() != 15) {
            throw new IllegalArgumentException('Invalid ID length: ' + id15.length());
        }
        return String.valueOf((Id) id15);
    }
    
    // Convert 18-digit to 15-digit
    public static String to15Digit(String id18) {
        if (String.isBlank(id18)) return null;
        if (id18.length() == 15) return id18;
        if (id18.length() != 18) {
            throw new IllegalArgumentException('Invalid ID length: ' + id18.length());
        }
        return id18.substring(0, 15);
    }
}

JavaScript

Key Points

Aspect	15-digit	18-digit
Case sensitivity	Case-sensitive	Case-insensitive
Use case	UI, URLs	Apex, APIs, integrations
SOQL comparison	Works but risky	Recommended



Best practice: Always use 18-digit IDs in Apex code and integrations to avoid case-sensitivity issues, especially when comparing IDs from external systems or CSV imports.