This is a answer to a similar question.  Does it help? 
From: [log in to unmask] [[log in to unmask]] on behalf of Nathan Tallman [[log in to unmask]]
Sent: Thursday, March 28, 2013 2:41 PM
To: Encoded Archival Description List; Archivists' Toolkit User Group
Subject: [atug-L] Re: Extent Measurements

Barb, thanks for your response.

Currently, we do not measure everything in linear feet. We'll say something like 2 folders or 4 videocassettes. But, let me provide some context for my question.

The impetus was accessions reporting within Archivists Toolkit. It adds up all the extent numbers, regardless of the extent measurement. So, while most things may be in linear feet, if you have 3 videocassettes, it just adds 3 to the total, no matter what the unit is.

Of course, this makes getting an accurate idea of how much material your taking in difficult. I was thinking it would be better to standardize everything to a linear foot measurement, to have a more accurate extent measurement, using the container summary to indicate 3 videocassettes or whatever the case may be. It'd be nice to have multiple extent statements that reflect in the reporting.

(I know BYU developed a plugin for this, but it doesn't migrate old extent data. Also, the reports would need to be modified to reflect the multiple extent units. I've had too many headaches trying to customize Toolkit reports...)

Have others who use Archivists' Toolkit faced similar situations? If so, how did you handle it? (Perhaps I'm missing something obvious within Toolkit.)

Many thanks,

On Thu, Mar 28, 2013 at 2:02 PM, Aikens, Barbara <[log in to unmask]<mailto:[log in to unmask]>> wrote:
Hi Nathan,

We adopted an old Yale extent formula for containers a long time ago and have stuck by it; we don�t usually measure folders in terms of linear feet.  If a collection is really small, we might count the number of folders the total collection extent.   We might also use the # of folders as the extent for a series/subseries if it is less than 0.2 linear feet (1/2 size document box.)

1 records storage box = 1 linear foot or 1.25 cubic feet
1 document/manuscript box = 0.4 linear feet
1 � size document/manuscript box = 0.2 linear feet
1 oversized flat box = 0.3 linear feet (we rarely use varied sizes of flat boxes)
1 oversized folder = 0.1 linear feet (not really accurate, but we�re stickin� to it!)

It�s hard to mix items and containers and make it all make sense according to linear feet.   For AV extent in a mixed materials collection, we generally use the measurement of the container that actually houses the audiovisual item/items.
However, I could see a �mixed extent� also working, such as �0.4 linear feet; 2 sound recordings.�

For us, consistency is key because we barcode all of our containers and have extent measurements attached to those barcode items.  This is how we�re able to do statistical reports on our holdings.


Barbara D. Aikens
Chief, Collections Processing | Archives of American Art, Smithsonian Institution
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From: Encoded Archival Description List [mailto:[log in to unmask]<mailto:[log in to unmask]>] On Behalf Of Nathan Tallman
Sent: Thursday, March 28, 2013 1:16 PM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: Extent Measurements

Apologies for cross posting!

Does anybody have a handy chart or reference for what they use to estimate extent measurements? I'm thinking about when a collection comes in of 3 audiocassettes or if a collection is 7 Hollinger boxes and 4 DVDs. I've seen estimates for folders (ranging from 0.01 to 0.04+ linear feet), but never a comprehensive list.

Something that gives a measurement per unit. For example:

audiocassette    0.02 linear feet
record carton     1.00 linear feet
folder                 0.02 linear feet
CD-ROM            0.01 linear feet

Many thanks!