• Welcome to the Lightroom Queen Forums! We're a friendly bunch, so please feel free to register and join in the conversation. If you're not familiar with forums, you'll find step by step instructions on how to post your first thread under Help at the bottom of the page. You're also welcome to download our free Lightroom Quick Start eBooks and explore our other FAQ resources.
  • Stop struggling with Lightroom! There's no need to spend hours hunting for the answers to your Lightroom Classic questions. All the information you need is in Adobe Lightroom Classic - The Missing FAQ!

    To help you get started, there's a series of easy tutorials to guide you through a simple workflow. As you grow in confidence, the book switches to a conversational FAQ format, so you can quickly find answers to advanced questions. And better still, the eBooks are updated for every release, so it's always up to date.

Library module limit on total length of all keywords?


Lightroom enthusiast (and still learning)
Premium Classic Member
Nov 16, 2015
Palo Alto, California, USA
Lightroom Experience
Lightroom Version
Lightroom Version Number
Classic 13.2
Operating System
  1. Windows 10
I'm aware of the long-standing bug that limits keyword display to about 1500 or 2000 items. A workaround seems to be to use nested keywords. I'm concerned that the total size of all keywords as a text string could also be limited, either in the keyword part of the catalog or on export. So before I go down this rabbit hole, I need some advice.

I'm planning to add keywords for photos for my hobby, railroads. I need to create keywords to capture rail subject-specific informationn. (Once I thought that custom metadata would be the best way to input rail subject-specif information, but it's clear that XMP custom metadata seems to have zero industry adoption.)

One important keyword n is the name of the railroad system, e..g. Union Pacific Railroad or British Rail. Ideally, I would have a separate keyword for each system, e.g.
SystemName-Union-Pacific-Railroad or SystemName-British-Rail. Between the US and Europe, I could easily imagine 125 systems, including national/regional systems and urban metro systems,, some with very long names, e.g. Societé Nationale des Chemins de Fer Français. Could I run into a size issue here?

I can see two modifications to this approach that might reduce total text size:

1. Use just initials., e.g. UPRR or BR or SNCF.
2. I would rathernot use just the SystemNames keyword with a separate keyword for each system name. This approach would have the disadvantage of separating the actual system name from the SystemName keyword.

Phil Burton
You are right about the number of items that can be displayed in the Keyword List panel on Windows. It's roughly 2000, some kind of hierarchy is a workaround, and there's little chance that Adobe will fix the problem.

But a limit where, Phil? What you need to consider is not just what Lightroom will allow, but also what is allowed in other environments.

From the IPTC standard, an individual keyword was limited to 64 characters under the old IIM format but is unlimited if it's in the XMP section. Some applications enforce the old limits, others don't, and you need to look at the exact application and circumstance to be sure. Some online apps simply strip the metadata anyway. The devil is in the detail. If necessary, I think I'd use keywords longer than 64 characters.

As well as the technical limitations, I think you also need to think about the "data model".

If I needed more than 64 characters for a keyword, I'd really question whether that keyword should in fact be more than one keyword. It's a bit like comparing English to German or Welsh or other more-agglutinative languages (longer multi-element words, lengthier dictionaries), but breaking up multi-element keywords also allows for the flexibility of organisations over time. Think of companies and how they acquire subsidiaries, add the corporate name as a prefix, and then sell off that subsidiary and another corporate adds its name and other branding.

Trying to think in railway terms, the Tiny Mountain Railroad is an entity or search term in its own right. You can imagine searching for Tiny Mountain Railroad and finding all pictures of the same "thing" as it passed throughperiods when it was owned by Northern Rail, then DB or SNCF. If you want pictures of that line with a particular company livery, then you'd also search for Northern Rail or DB or SNCF.

Equally, searching for DB would return all the DB-owned companies, instead of having to search for DB Tiny Mountain Railroad, DB ICE, DB Freight.... Sure, in this case you could make this work for searches by looking for keywords with the DB element, but that's harder with more generic names like Northern which exist in more than one country or state. Additionally, remember how things change over time. Tiny Mountain Railroad might be bought by DB, but only change its name and use DB livery after a year or two, then change livery but not the name etc. Each of these, the thing / organisation / livery is really a different aspect of the photo, a way it might be described on its own or categorised and grouped with others, and each aspect or "dimension" is best reflected in its own keyword.

You as well as organisations change. What if you decide you prefer Deutsche Bahn or want it as a synonym? Separating the system name means there's one keyword to alter.

Also, keywords aren't titles or captions.

Hope those ideas help your thinking!
Besides the limit on the number of keywords that can be displayed in the Keyword List panel, the only other limit I'm aware of is on the length of a custom metadata field provided by a plugin. A field value can be of arbitrary length, but LR will only search the first 512 characters. I haven't observed any limit on built-in metadata fields.