Why do some psalm numbers have a different number in brackets?
By CopticBot.ai (Coptic Space Inc.) · Last reviewed 2026-10-09
The difference in Psalm numbering—where you see one number followed by another in brackets, such as Psalm 50 [51] or Psalm 23 (22)—is due to a historical divergence between two primary textual traditions of the Old Testament:
- The Septuagint (LXX): The ancient Greek translation of the Hebrew Scriptures produced in Alexandria, Egypt, around the 3rd to 2nd century BC. This is the official textual tradition preserved and used by the early Church and the Orthodox Church, as well as the ancient Latin Vulgate.
- The Masoretic Text (MT): The standardized Hebrew text compiled by Jewish scribes (the Masoretes) between the 6th and 10th centuries AD, which became the standard base text for Western translations following the Protestant Reformation (such as the King James Version and most modern English Bibles).
Both traditions contain the same total number of canonical Psalms (150), but they divide and combine certain individual Psalms differently.
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Where the Numbering Diverges
The divergence begins after Psalm 8:
| Septuagint (LXX) / Orthodox / Vulgate | Masoretic Text (MT) / Protestant / Modern Bibles | Explanation |
| :--- | :--- | :--- |
| Psalms 1–8 | Psalms 1–8 | Numbering is identical. |
| Psalm 9 | Psalms 9 and 10 | The LXX preserves this as a single acrostic psalm; the MT splits it into two. |
| Psalms 10–112 | Psalms 11–113 | Because of the split above, the LXX is one number behind the MT (e.g., LXX Ps 50 = MT Ps 51; LXX Ps 22 = MT Ps 23). |
| Psalm 113 | Psalms 114 and 115 | The LXX unites these into one psalm; the MT divides them. |
| Psalms 114 and 115 | Psalm 116 | The LXX divides this into two (vv. 1–9 and vv. 10–19); the MT keeps it as one. |
| Psalms 116–145 | Psalms 117–146 | The numbering remains shifted by one. |
| Psalms 146 and 147 | Psalm 147 | The LXX divides this into two; the MT keeps it as one. |
| Psalms 148–150 | Psalms 148–150 | Numbering realigns and matches again. |
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Common Liturgical Examples
Because of this difference, publications often print both numbers so readers can identify the text regardless of which tradition or Bible translation they are using:
- The Great Penitential Psalm ("Have mercy upon me, O God..."):
- In the Agpeya (the Coptic Book of Hours) and the Septuagint, it is Psalm 50.
- In standard English Bibles relying on the Hebrew text, it is Psalm 51.
- Printed as: Psalm 50 [51] or Psalm 51 (50).
- "The Lord is my shepherd...":
- In the Septuagint, it is Psalm 22.
- In the Masoretic tradition, it is Psalm 23.
- Printed as: Psalm 23 [22] or Psalm 22 (23).
- Psalm 151:
- The Septuagint and the Orthodox tradition include Psalm 151 as a canonical psalm spoken by David regarding his victory over Goliath.
- Protestant Bibles omit Psalm 151 entirely because it was not preserved in the traditional rabbinic Masoretic canon (though Hebrew fragments of it were later found among the Dead Sea Scrolls at Qumran).
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Why the Septuagint Numbering Matters
The Septuagint was the Bible quoted directly by the Apostles in the New Testament and utilized by the early Church Fathers. The ancient liturgical hours and prayers of the Church have used the Septuagint numbering for two thousand years. The bracketed numbers serve as a cross-reference bridge between our historic liturgical numbering and modern Bible editions.