Birta is the Icelandic word for "brightness" or "light." Used as a modern Icelandic feminine name evoking the Nordic summer's endless daylight.
Birta is widely used in modern Iceland.
Birta does not currently appear in the US Social Security Administration's top 1,000 girls' names, so we don't publish a US rank or birth count for it. That says nothing about the name's standing elsewhere in the world — only that it sits outside the ranked US data we rely on.
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In Pythagorean numerology the letters of Birta reduce to 5, The Seeker. This is a traditional interpretive system, not a factual claim about the name.