What is #21stbirthday used for?

#21stbirthday is a popular hashtag used on Instagram, TikTok, YouTube, and LinkedIn to categorize content. It has 6 related hashtags. The best hashtags to pair with #21stbirthday are: #21st, #21, #birthdaycake, #birthday, #happybirthday.

What are the best hashtags to use with #21stbirthday?

Based on analysis of 29 posts, the top hashtags to combine with #21stbirthday are: #21st, #21, #birthdaycake, #birthday, #happybirthday. These have high relevance scores averaging 14% and are used by 70% of top-performing posts.

How many hashtags should I use with #21stbirthday?

For Instagram, use 20-30 hashtags including #21stbirthday. For TikTok, use 3-5 hashtags. For YouTube, use 3-5 in description. For LinkedIn, keep it to 3-5 professional hashtags. Studies show this can increase engagement by +35%.

How do I use #21stbirthday on Instagram?

On Instagram, add #21stbirthday in your caption or first comment with 20-30 related hashtags. Best tags to combine: #21st, #21, #birthdaycake. Use in Stories and Reels for extra discovery.

Does #21stbirthday work on TikTok?

Yes! Use #21stbirthday with 3-4 related hashtags like #21st and #21. Posts using #21stbirthday see 2.5x more reach on average. TikTok prioritizes content quality, so pair with trending sounds.

Can I use #21stbirthday on YouTube?

Yes, add #21stbirthday to your video title — first 3 hashtags appear above the title. Include related tags like #21st, #21 in your description. Works great for YouTube Shorts.

Is #21stbirthday still popular in 2026?

Yes! #21stbirthday remains highly popular in 2026 with 6 related hashtags and 29+ posts analyzed. 70% of top-performing posts in this niche use #21stbirthday or related tags.

What hashtags are similar to #21stbirthday?

Similar hashtags to #21stbirthday include: #21st, #21, #birthdaycake, #birthday, #happybirthday, #cake. These share 14% average relevance and can increase reach by 2.5x when used together.

#21stbirthday

Discover 6 trending hashtags related to #21stbirthday for Instagram, TikTok, YouTube & LinkedIn in 2026.

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Best hashtags to use with #21stbirthday:

#21st, #21, #birthdaycake, #birthday, #happybirthday

Based on analysis of 29 posts • 6 related hashtags found

📊 #21stbirthday Statistics & Insights

70%

of top posts use related tags

2.5x

avg reach with #21stbirthday

+35%

engagement boost

optimal hashtags (IG)

Data based on analysis of 29+ posts using #21stbirthday • Updated 2026

Related Tags

Post Connections

14%

Avg Relevance

Copy & Paste #21stbirthday Hashtags

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Instagram Hashtags

30 hashtags • Caption or comment

#21stbirthday #21st #21 #birthdaycake #birthday #happybirthday #cake

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TikTok Hashtags

5 hashtags • Video caption

#21stbirthday #21st #21 #birthdaycake #birthday

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YouTube Hashtags

5 hashtags • Title & description

#21stbirthday #21st #21 #birthdaycake #birthday

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LinkedIn Hashtags

5 hashtags • Professional posts

#21stbirthday #21st #21 #birthdaycake #birthday

Related Hashtags for #21stbirthday

Click any hashtag to explore its related tags

6 tags

How to Use #21stbirthday on Each Platform

Platform-specific strategies to maximize your reach with #21stbirthday

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Instagram

20-30 hashtags recommended

✓Add #21stbirthday in your caption or first comment
✓Mix #21st, #21, #birthdaycake for best reach
✓Use in Stories and Reels for extra discovery
✓Combine popular hashtags with niche-specific ones
→Pro tip: Save hashtag sets for quick reuse

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TikTok

3-5 hashtags recommended

✓Less is more — use #21stbirthday + 3-4 related tags
✓Check FYP trends for #21stbirthday variations
✓Pair with trending sounds for algorithm boost
✓Content quality matters more than hashtag count
→Pro tip: Add hashtags at end of caption

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YouTube

3-5 hashtags recommended

✓Add #21stbirthday in video title for visibility
✓First 3 hashtags show above video title
✓Include in description with related: #21st, #21
✓Add to video tags for search ranking
→Pro tip: Use Shorts with hashtags for discovery

💼

3-5 hashtags recommended

✓Keep #21stbirthday professional and industry-relevant
✓Add hashtags at the end of your post
✓Follow #21stbirthday to engage with community
✓Combine with thought leadership content
→Pro tip: Check hashtag followers before using

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Explore More Hashtags

Best #21st hashtags Best #21 hashtags Best #birthdaycake hashtags Best #birthday hashtags Best #happybirthday hashtags Best #cake hashtags

#21stbirthday

Best hashtags to use with #21stbirthday:

📊 #21stbirthday Statistics & Insights

Copy & Paste #21stbirthday Hashtags

Related Hashtags for #21stbirthday

How to Use #21stbirthday on Each Platform

Instagram

TikTok

YouTube

LinkedIn

People Also Ask About #21stbirthday

What is #21stbirthday used for?

How many hashtags should I use with #21stbirthday?

What are the best hashtags to use with #21stbirthday?

Does #21stbirthday work on TikTok?

How do I use #21stbirthday on Instagram?

Is #21stbirthday still popular in 2026?

What hashtags are similar to #21stbirthday?

How to get more likes with #21stbirthday?

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