What is my brother's girlfriend to me?
Your brother's girlfriend has no kinship term: English only hands out in-law titles at a wedding. Most people say "my brother's girlfriend" or use her name. If they marry, she becomes your sister-in-law, and some families start saying "future sister-in-law" once there's an engagement.
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Brother's girlfriend
English has no word for this person until there's a wedding. Families just say “brother's girlfriend”.
- You
- Your brother
- His girlfriend
From the other side, you are their boyfriend's sibling.
A partner who hasn't married into the family has no family link for the ancestor chart to draw.
The calculator below works out blood relationships through a shared ancestor — use it to explore the rest of your tree.
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This relationship sits outside the shared-ancestor model, so the card above carries the answer and the calculator opens in its default state. Work out any blood relationship with it, or open the full relationship calculator.
Related questions
FAQs
Is my brother's girlfriend my sister-in-law?+
Not yet. The title comes with the wedding. Some families use "future sister-in-law" once there's a ring.
Who am I to my brother's girlfriend?+
Her boyfriend's sibling, which has no title either.
Does the calculator store my family details?+
No — it runs entirely in your browser. Nothing you enter is uploaded or saved on our servers.
Start with one relative and see what comes back.
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