Antonio Lopes
Founder and operator, MyBookWorth · Portugal
I built MyBookWorth because I could not find a straight answer to a simple question: what has a book like this one actually sold for? Plenty of sites will give you a confident number. Very few will show you the sales that number came from.
So I built the other thing. MyBookWorth runs on a database of roughly 800,000 real auction and marketplace results — antiquarian and collectible books, antique maps, and antique prints. When you search, it finds genuinely comparable lots and links you to the original listing so you can check the price yourself. It does not invent a valuation, because a single number cannot honestly describe an object whose worth turns on edition, printing, condition, and provenance.
What I actually am
I am a software engineer, not an antiquarian bookseller. I do not authenticate signatures, I do not grade condition, and I would not ask you to take my word on whether your copy is a true first printing.
What I do have is the data, and the tools to interrogate it. The guides on this site are written from aggregate analysis of those 800,000 results — median prices, how value actually distributes across centuries, which features carry a premium and which are folklore. Where a guide states a number, that number comes from the database and I will tell you the sample it came from. Where the data contradicts received wisdom, I say so rather than repeating the received wisdom.
How I work
- Every price shown is a real, historical, third-party result — never an estimate I generated.
- Every listing links back to its source so you can verify it.
- Figures in the guides are stated with their sample size, so you can judge their weight.
- Where the data is thin or the answer is “it depends”, the guide says that.
If something here is wrong, or a listing should not be included, write to me at [email protected] and I will fix it.
Guides by Antonio Lopes
- Do Multi-Volume Sets Sell for More?
Across 13,854 multi-volume lots, a set barely beats a single book — and the price per volume collapses from €30 to €2 as the set grows.
- What Collectable Photobooks Sell For
We priced 17,967 photobook lots by 99 named photographers. The typical one makes €62, and a signature is worth more here than in books generally.
- Whose Signatures Are Worth Least
For 31 of 165 authors, signed copies sold for less than unsigned ones. The reason is not fame — it is where the rare books ended up.
- What a Signature Is Really Worth
We compared signed and unsigned copies across 800,000 auction sales. A famous name can multiply the price eightfold; most authors barely move it.
- What a First Edition Is Actually Worth
Books described as first editions sold for barely more than everything else. Why the label is weak, and what actually carries the value.
- How to Identify a First Edition
Number lines, copyright pages, book club tells and issue points: the checks that turn a claimed first edition into a verified one.
- Is My Old Book Worth Anything?
We looked at 605,255 real auction sales of old books, maps and prints. Seven in ten sold for under €100. Here is how to place your own.
- How to Read an Auction Result
A sold price is evidence; an asking price is an opinion. Here is how to read the comparable sales this site returns, in about five minutes.
- Does Age Make a Book Valuable?
We priced 446,180 dated auction lots by century. Age helps far less than people think, and after 1800 it stops helping almost entirely.
- What Antique Maps Are Worth by Region
A map of Spain typically sells for €77 and a map of France for €42, from the same engravers. Here is the going rate for 34 regions.
- Which Antique Map Makers Sell Best
Blaeu is the name every collector knows, yet across 53,715 map lots he sells for €84 while Braun & Hogenberg reach €96. Here is why.