How do Bilibili BV and AV numbers relate, and which one should I store?

Every Bilibili video has a numeric archive id, the aid, which used to appear in links as av170001. On 23 March 2020 Bilibili switched its links to BV ids such as BV17x411w7KC. The BV id is not a new key: it is the aid run through a fixed, reversible encoding. One video, one aid, one BV id, and you can turn either into the other with a few lines of code and no network call.

What each one looks like

	AV number (aid)	BV id (bvid)
Shape	A positive integer, written av + digits in old links	BV1 + 9 characters, 12 in total
Characters	0-9	A 58-character alphabet without 0, I, O and l
Where you see it	Old links, comment-area mentions, many older datasets	Every current link, share link and app screen
In okdata responses	ext.aid (with view=full)	id of every Bilibili post

Not to be confused with cid, which numbers each part of a multi-part video (ext.cid on video detail), or the ep/ss numbers of anime and drama episodes.

How the conversion works

The current algorithm handles aids up to 2^51. To encode, set bit 51 on the aid, XOR it with 23442827791579, write the result in base 58 with the alphabet FcwAPNKTMug3GV5Lj7EJnHpWsx4tb8haYeviqBz6rkCy12mUSDQX9RdoZf, prefix BV1, then swap the characters at positions 3 and 9, and 4 and 7 (counting from 0). Decoding runs the same steps backwards and masks with 2^51 - 1.

Worked example for av170001: 2^51 OR 170001 is 2251799813855249; XOR 23442827791579 gives 2275242641642698; in base 58 that is 7141xw7KC, so BV17141xw7KC; after the two swaps, BV17x411w7KC. We ran the same code on 20 videos from the Bilibili popular board, aids of 15 digits included, and every pair matched.

Which one to store

Key your tables on the BV id. It is what users paste, what share links carry, and what Bilibili video detail and Bilibili video comments accept as id. Keep the aid in a BIGINT column next to it when you need to join older data. Never treat BV ids as case-insensitive: BV17x411w7KC and bv17X411W7kc are different strings.

What you have	What to do	Cost
An AV number	Convert to BV locally, then look it up	$0.002
A BV id, want the aid	Convert locally	free
Search results	id is the BV id, ext.aid the aid	$0.002 a page
1,000 old aids to refresh	Convert, then 1,000 lookups	$2.00

Example

XOR, MASK, TOP, BASE = 23442827791579, (1 << 51) - 1, 1 << 51, 58
ABC = "FcwAPNKTMug3GV5Lj7EJnHpWsx4tb8haYeviqBz6rkCy12mUSDQX9RdoZf"

def av_to_bv(aid: int) -> str:
    n, out = (TOP | aid) ^ XOR, []
    while n:
        n, r = divmod(n, BASE)
        out.append(ABC[r])
    s = list("BV1" + "".join(reversed(out)))
    s[3], s[9], s[4], s[7] = s[9], s[3], s[7], s[4]
    return "".join(s)

def bv_to_av(bvid: str) -> int:
    s = list(bvid)
    s[3], s[9], s[4], s[7] = s[9], s[3], s[7], s[4]
    n = 0
    for ch in s[3:]:
        n = n * BASE + ABC.index(ch)
    return (n & MASK) ^ XOR

assert av_to_bv(170001) == "BV17x411w7KC" and bv_to_av("BV17x411w7KC") == 170001

To check one against Bilibili itself, ask video detail for the aid it holds:

curl -G "https://api.okdata.online/v1/bilibili/videos/get" \
  -H "Authorization: Bearer $OKDATA_API_KEY" \
  --data-urlencode 'id=BV17x411w7KC' \
  --data-urlencode 'view=full' \
  --data-urlencode 'fields=id,title,ext.aid,ext.cid'

Limits

• The endpoint takes a BV id or a bilibili.com/video/BV... link. An av link is refused as invalid_params, which is not charged; convert it first.
• The algorithm is Bilibili's, not a standard. If Bilibili changes it again, ids minted after the change may not decode, so keep the BV id the platform gave you rather than only the aid.
• bilibili-API-collect, long the usual reference for this algorithm, was taken down in January 2026 after a lawyer's letter from Bilibili. Small libraries such as abv still publish the code.

For the stats behind a BV id, see getting views, coins and danmaku for a BV id.