American Standard Version
The king shall joy in thy strength, O Jehovah; And in thy salvation how greatly shall he rejoice!

Berean Study Bible
For the choirmaster. A Psalm of David. O LORD, the king rejoices in Your strength. How greatly he exults in Your salvation!

Douay-Rheims Bible
Unto the end. A psalm for David. In thy strength, O Lord, the king shall joy; and in thy salvation he shall rejoice exceedingly.

English Revised Version
For the Chief Musician. A Psalm of David. The king shall joy in thy strength, O LORD; and in thy salvation how greatly shall he rejoice!

King James Bible
To the chief Musician, A Psalm of David. The king shall joy in thy strength, O LORD; and in thy salvation how greatly shall he rejoice!

World English Bible
The king rejoices in your strength, Yahweh! How greatly he rejoices in your salvation!

Young's Literal Translation
To the Overseer. -- A Psalm of David. Jehovah, in Thy strength is the king joyful, In Thy salvation how greatly he rejoiceth.

Psalm 21:1 Additional Translations ...