How to calculate how much storage a CSV will use when uploaded to SObject

Question

So I have a .csv file that contains ~12,000 rows and on my local filesystem takes up about 3MB of data. I assumed that when I imported this csv into a Salesforce Object, the data would still take up around 3MB of space, however it ends up taking over 25MB of space.

I'm trying to figure out what causes the discrepancy between storage sizes (I assume that there are some metadata files that get created and are counted agains the org limits, however an extra 22MB of data seems unnecessary). Does anyone know what causes this and/or how I could accurately predict how much Salesforce storage a CSV file would consume before importing it into an SObject?

Thank you!

The CSV File in my File System:

The Size of the Data once imported into an SObject:

Answer 1

Each SObject record in Salesforce consumes a flat 2kB of your "Data" limit, regardless of how much (or how little) actual data it contains. Everyone gets a base 10GB of "Data" storage, with an additional 20MB per regular user license¹ (so this doesn't count "free chatter users" and the like)

12,969 records * 2kB = 25.938MB Data space used

The notable exception to this is the TextBody and HtmlBody fields of the EmailMessage SObject, which consume 2kB (for the base SObject record) + every single bit in those two fields. There are a few other objects that go above 2kB, as documented in this help article

Reproduced here

SObject	"Data" storage used
Leads	2KB
Contacts	2KB
Accounts	2KB
Person Accounts	4KB
Opportunities	2KB
Forecasts	2KB
Events	2KB
Tasks	2KB
Cases	2KB
Case Team Member	2KB
Solutions	2KB
Notes	2KB
Custom Reports	2KB
Campaigns	8KB
Campaign Members	1KB
Contracts	2KB
Google Docs	2KB
Quotes	2KB
Quote Line Items	2KB****
Orders	2KB****
Work Order Line Items	2KB****
Tags: unique tags	2KB
Custom Objects	2KB
Quote Template Rich Text Data	2KB
Articles	4KB*
Email Message	2KB**
Person Accounts	4KB***

^{1: 20MB for Contact Manager, Group, Professional, and Enterprise editions. 120MB for Performance and Unlimited editions.}