Cloudflare R2 to Backblaze B2: Move Cold Buckets and Cut Storage Cost by More Than Half

The Cost Math

Cloudflare R2 and Backblaze B2 price the same thing in opposite ways: R2 charges more to store and nothing to download, B2 charges less than half as much to store and includes free downloads only up to three times what you keep there.

Storage only, 1 TB = 1,000 GB. Prices checked October 2026 on the R2 pricing page and the B2 pricing page.

Where the break-even sits. B2 includes free egress up to 3x your average stored volume, then charges $0.01 per GB. Each TB moved to B2 saves $8.05 a month, which pays for 805 GB of overage, so B2 stays cheaper until a bucket is downloaded about 3.8 times its own size in a month. Backups, database dumps, log archives and finished projects sit far below that line; public images, downloads and Worker assets often sit above it and belong on R2.

What the move itself costs. Listing a bucket is a Class A operation (up to 1,000 keys per call, 1 million free per month, then $4.50 per million). Reading each object is Class B (10 million free, then $0.36 per million). There is no egress fee and no retrieval fee on Standard storage, and B2 charges nothing for uploads. A 5 TB bucket of 1 million Standard objects therefore costs close to nothing to move. Objects in R2 Infrequent Access are the exception: they carry a $0.01 per GB retrieval fee, about $50 for 5 TB.

Phase 1 — Prepare the B2 Side

Most migration problems on this route come from B2 defaults that nobody changed. Do these before any data moves:

1. Create the bucket under Buckets → Create a Bucket and leave it private.
2. Change its versioning. B2 keeps every version of a file by default, and a deleted file is only hidden, so overwrites during a re-run are stored — and billed — twice. Open the bucket's Lifecycle Settings and choose Keep only the last version; the old copy is then hidden for a day and deleted (lifecycle rules).
3. Check Caps & Alerts. A daily storage or transaction cap set long ago will stop a large upload halfway.
4. Create an application key under Application Keys → Add a New Application Key, with Read and Write access to all buckets or to the target bucket. Copy the keyID and applicationKey; the key is shown only once.
   
5. Collect the R2 credentials. In the Cloudflare dashboard, open R2, copy your Account ID (it forms the endpoint https://<ACCOUNT_ID>.r2.cloudflarestorage.com) and open Manage R2 API Tokens.
   
   Create a token. Admin Read & Write can list every bucket; an Object Read & Write token cannot list buckets even when applied to all of them, so with that type you will have to name the bucket. Copy the Access Key ID and Secret Access Key — Cloudflare shows them once.
   

Phase 2 — Copy the Objects

Super Slurper and Sippy only copy data into R2, and Backblaze's Universal Data Migration lists AWS, Azure, Google Cloud and Wasabi as sources, so the copy needs a third tool. Two handle whole buckets well. For a few gigabytes, a desktop S3 client such as S3 Browser or Cyberduck plus the B2 web uploader is enough, at the cost of routing everything through your own connection twice.

Option A: rclone on a server you already run

rclone reads R2 through its S3 backend and writes B2 through its native backend. The data streams through the machine running it, so use a server with good bandwidth. In rclone.conf:

[r2]
type = s3
provider = Cloudflare
access_key_id = YOUR_R2_ACCESS_KEY_ID
secret_access_key = YOUR_R2_SECRET_ACCESS_KEY
endpoint = https://YOUR_ACCOUNT_ID.r2.cloudflarestorage.com

[b2]
type = b2
account = YOUR_B2_KEY_ID
key = YOUR_B2_APPLICATION_KEY

rclone copy r2:archive-bucket b2:archive-bucket --fast-list --transfers 16 --progress

Use copy, not sync or move, until Phase 4.

Option B: CloudsLinker, with nothing to run yourself

CloudsLinker reads R2 over the S3 API and writes B2 over the native B2 API on its own servers, so there is no machine to rent or watch. It uses the keys you collected in Phase 1.

Click Add Cloud and choose Cloudflare R2. Enter a name, the Access Key ID, the Secret Access Key and the Endpoint with your own account ID. Fill in Bucket only if you created an Object Read & Write token.

Click Add Cloud again and choose Backblaze B2. Put the keyID in Account ID or Application Key ID and the secret in Application Key; B2 connects through its native API, so the Endpoint field can stay empty.

On Create transfer task, pick the R2 bucket or a prefix as the source and a folder in the B2 bucket as the target (the target side selects folders only and can create a new one). Leave the mode on Copy — Move deletes each object from R2 after copying. The default conflict strategy re-sends a same-name file only when its size differs or its date is newer, which keeps re-runs from creating B2 versions. Filters accept file extensions or a size range in MB.

Click Create transfer and follow the task in Task monitor (All, Running, Scheduled and Failed tabs, Retry on finished tasks). The browser can be closed while it runs. In the example below, Task1 was a trial run on the logs prefix; when Task2 reaches those objects they already sit in B2 unchanged, so they are counted under Skipped instead of being uploaded a second time.

Phase 3 — Verify the Copy

Object size limits are not a concern: R2 objects top out at 4.995 TiB and B2 large files at 10 TB (R2 limits, B2 large files).

Phase 4 — Cut Over and Clean Up

1. Catch up on new writes. If the bucket is still in use, re-run the copy — or save the CloudsLinker task with a weekly or monthly schedule (paid plans) — so only new or changed objects are sent.
2. Repoint what reads the data. Backup tools, scripts, Workers and public URLs that use R2 need the B2 endpoint and keys.
3. Stop writing to R2 and run one last pass.
4. Delete from R2 after a waiting period. Deletes are free; objects in Infrequent Access are billed for 30 days regardless. If you use rclone sync or move against B2 from here on, remember that files removed on the B2 side are hidden and still billed unless you add --b2-hard-delete.
5. Revoke the migration keys — the R2 API token and the B2 application key.