G: Short version: yes, probably. The cleanest path is usually:

1. Clone/import the old library or add the same files into the new one.
2. Create matching custom columns in the new DB.
3. Use Calibre’s bulk Search & Replace metadata tools to copy values from standard fields (like Author) into your new custom columns.
4. Then optionally clear or repurpose the original fields.

The important thing is that Calibre stores metadata in its DB independently from the actual files, so if you just re-add the files raw, you may lose the structured data unless you migrate intelligently. citeturn0search26turn0search5

A few workable approaches:

---

Method 1 — Probably the easiest: clone + remap fields

If the same files already exist in the old database:

Step A — Clone the old library structure

Calibre has a built-in “clone library” feature which copies:

• custom columns
• virtual libraries
• settings/layouts

without copying the books themselves. citeturn0search26

This matters because custom columns are internally identified by lookup names like:

• #media_type
• #archive_source

not just by visible column names.

If your new DB already exists:

• back it up first
• then consider recreating the column structure to match the old DB temporarily.

---

Method 2 — Bulk-copy one column into another

This is probably what you actually want.

Example:

• old DB used:
  • Author = creator
• new DB uses:
  • custom field #creator

Calibre can bulk copy metadata between columns using:

• Bulk Edit Metadata
• Search & Replace tab

This is a known/common workflow. citeturn0search15turn0search18

Example procedure

Select all items:

• Press E
• Go to: Search & Replace

Then:

• Search field: authors
• Search mode: regular expression OR normal
• Search for: leave blank
• Replace with: leave blank
• Destination field: #creator

That effectively copies contents from: authors → #creator

People use the same trick for:

• tags → custom column
• series → custom column
• dates → other dates etc. citeturn0search18turn0search15

---

Method 3 — Use Export/Import metadata (best for massive restructures)

If your schemas diverged heavily:

• export metadata
• remap externally
• re-import

Possible via:

• CSV
• OPF
• calibredb CLI
• plugins like Import List

There are users doing this through CSV/plugin workflows specifically to avoid retyping metadata. citeturn0search9turn0search36

This becomes useful if:

• multiple fields changed meaning
• one field became several fields
• you want scripted transformations

---

Method 4 — Direct SQLite surgery (possible, but dangerous)

Because Calibre stores everything in metadata.db (SQLite), technically you can:

• inspect tables directly
• mass-update values
• migrate columns

BUT:

• Calibre developers strongly prefer you not edit the DB manually
• schema is nontrivial
• easy to corrupt relationships

Given your use case, the built-in metadata tools are probably safer and easier.

---

One important gotcha

Custom columns are tied to internal lookup names.

Example:

• visible column name: Creator
• internal field: #creator

If the new DB has:

• same visible name
• different lookup name

Calibre treats them as different fields.

So before migration:

• go to: Preferences -> Add your own columns
• compare the lookup names carefully.

This is probably the single biggest thing that determines whether the migration becomes painless or miserable.

---

What I would personally do in your situation

Given your description:

Safest workflow

1. Backup both libraries.
2. Open old DB.
3. Write down:
   • custom columns
   • lookup names
   • intended mapping.
4. Modify the NEW DB so it temporarily mirrors the OLD structure.
5. Use:
   • Add books from old library OR
   • Copy to library
6. Once metadata is present:
   • bulk-copy fields into their new destinations.
7. Delete obsolete columns afterward.

That avoids:

• CSV headaches
• plugin dependence
• manual re-entry
• SQLite surgery.

---

Useful references:

• urlCalibre metadata editing docshttps://manual.calibre-ebook.com/metadata.html
• urlcalibredb command documentationhttps://manual.calibre-ebook.com/generated/en/calibredb.html
• urlMobileRead discussion on copying columnshttps://www.mobileread.com/forums/showthread.php?t=356771

[Attachment reference unresolved: file-using]

G: Yeah, Calibre’s UI for this is weirdly unintuitive because it calls it “Search & Replace” even when you’re really trying to do a field copy.

What you want is usually this:

• Search field = source column
• Destination field = target column
• Mode = “Regular expression”
• Search for = (.*)
• Replace with = \1

That regex just means:

• grab the entire contents of the source field
• paste it into the destination field unchanged.

So for your example:

• Source field: authors
• Destination field: #creator

You’d do:

Setting	Value
Search field	authors
Mode	Regular expression
Search for	(.*)
Replace with	\1
Destination field	#creator

Then hit OK/apply.

A couple important notes:

• authors is the internal field name for Author.
• Custom columns use their lookup name like:
  • #creator
  • #media
  • #source_archive

You can see those in: Preferences -> Add your own columns

Also:

• if the target field is “multiple values” and the source isn’t (or vice versa), weird formatting can happen.
• Author fields internally use Author1 & Author2 formatting, so if you had multiple authors, that separator may carry over literally unless transformed later.

One other extremely useful thing: before doing this to the whole database, test it on:

• one dummy entry or
• 2–3 selected entries

because Calibre bulk operations are very “yes I absolutely did exactly what you asked and now 8,000 records are weird.”