====== NDC Converter ======

The Converter tab converts National Drug Codes between 10-digit and 11-digit formats.

===== NDC Formats =====

NDCs come in two main formats:

  * **10-digit NDC** — The format printed on drug labels, with three segments separated by hyphens. There are three possible configurations:
    * **4-4-2** — e.g., 0071-0155-23
    * **5-3-2** — e.g., 12345-123-01
    * **5-4-1** — e.g., 12345-1234-1
  * **11-digit NDC** — The standardized format used in billing and claims, always formatted as **5-4-2** with zero-padding

===== How to Convert =====

  - Tap the **Converter** tab
  - Enter an NDC in any format (with or without hyphens)
  - Tap **Convert**
  - The app displays:
    * **10-digit NDC** — Original format
    * **11-digit NDC** — Zero-padded 11-digit code
    * **11-digit formatted** — With hyphens (5-4-2)

===== Conversion Rules =====

**10-digit to 11-digit:** The app detects which segment is "short" based on the hyphenated format and adds a leading zero to that segment:

  * 4-4-2 → **0**4444-4444-22 (zero added to first segment)
  * 5-3-2 → 55555-**0**333-22 (zero added to second segment)
  * 5-4-1 → 55555-4444-**0**1 (zero added to third segment)

**11-digit to 10-digit:** The app identifies which segment has a leading zero that can be removed and strips it.

**Important:**
A plain 10-digit NDC without hyphens is ambiguous — the app cannot determine the segment configuration. Always include hyphens when entering a 10-digit NDC.


===== Copy to Clipboard =====

Tap the converted NDC values to copy them to your clipboard.