What is #21km used for?

#21km is a popular hashtag used on Instagram, TikTok, YouTube, and LinkedIn to categorize content. It has 4 related hashtags. The best hashtags to pair with #21km are: #21k, #5km, #10km, #halfmarathon.

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

Based on analysis of 15 posts, the top hashtags to combine with #21km are: #21k, #5km, #10km, #halfmarathon. These have high relevance scores averaging 14% and are used by 75% of top-performing posts.

How many hashtags should I use with #21km?

For Instagram, use 20-30 hashtags including #21km. 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 #21km on Instagram?

On Instagram, add #21km in your caption or first comment with 20-30 related hashtags. Best tags to combine: #21k, #5km, #10km. Use in Stories and Reels for extra discovery.

Does #21km work on TikTok?

Yes! Use #21km with 3-4 related hashtags like #21k and #5km. Posts using #21km see 3.5x more reach on average. TikTok prioritizes content quality, so pair with trending sounds.

Can I use #21km on YouTube?

Yes, add #21km to your video title — first 3 hashtags appear above the title. Include related tags like #21k, #5km in your description. Works great for YouTube Shorts.

Is #21km still popular in 2026?

Yes! #21km remains highly popular in 2026 with 4 related hashtags and 15+ posts analyzed. 75% of top-performing posts in this niche use #21km or related tags.

What hashtags are similar to #21km?

Similar hashtags to #21km include: #21k, #5km, #10km, #halfmarathon. These share 14% average relevance and can increase reach by 3.5x when used together.

#21km

Discover 4 trending hashtags related to #21km for Instagram, TikTok, YouTube & LinkedIn in 2026.

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Best hashtags to use with #21km:

#21k, #5km, #10km, #halfmarathon

Based on analysis of 15 posts • 4 related hashtags found

📊 #21km Statistics & Insights

75%

of top posts use related tags

3.5x

avg reach with #21km

+35%

engagement boost

optimal hashtags (IG)

Data based on analysis of 15+ posts using #21km • Updated 2026

Related Tags

Post Connections

14%

Avg Relevance

Copy & Paste #21km Hashtags

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Instagram Hashtags

30 hashtags • Caption or comment

#21km #21k #5km #10km #halfmarathon

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TikTok Hashtags

5 hashtags • Video caption

#21km #21k #5km #10km #halfmarathon

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YouTube Hashtags

5 hashtags • Title & description

#21km #21k #5km #10km #halfmarathon

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LinkedIn Hashtags

5 hashtags • Professional posts

#21km #21k #5km #10km #halfmarathon

Related Hashtags for #21km

Click any hashtag to explore its related tags

4 tags

How to Use #21km on Each Platform

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

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Instagram

20-30 hashtags recommended

✓Add #21km in your caption or first comment
✓Mix #21k, #5km, #10km 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 #21km + 3-4 related tags
✓Check FYP trends for #21km 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 #21km in video title for visibility
✓First 3 hashtags show above video title
✓Include in description with related: #21k, #5km
✓Add to video tags for search ranking
→Pro tip: Use Shorts with hashtags for discovery

💼

3-5 hashtags recommended

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

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Explore More Hashtags

Best #21k hashtags Best #5km hashtags Best #10km hashtags Best #halfmarathon hashtags

#21km

Best hashtags to use with #21km:

📊 #21km Statistics & Insights

Copy & Paste #21km Hashtags

Related Hashtags for #21km

How to Use #21km on Each Platform

Instagram

TikTok

YouTube

LinkedIn

People Also Ask About #21km

What is #21km used for?

How many hashtags should I use with #21km?

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

Does #21km work on TikTok?

How do I use #21km on Instagram?

Is #21km still popular in 2026?

What hashtags are similar to #21km?

How to get more likes with #21km?

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