Size-specific adjustments to type designs

An investigation of the principles guiding the design of optical sizes

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Purpose of the book

The aim of this book is to determ­ine prin­ciples under­ly­ing the design of optical sizes, with a view to giving useful advice to prac­ti­tion­ers who wish to design such sizes for their own fonts.

What are optical sizes?

“Op­tical sizes” are size-specific adjust­ments to type designs. They were prac­ticed for 500 years of metal type print­ing. Since punches had to be cut separ­ately for each type size, adjust­ing them accord­ingly did not involve any addi­tional effort and the optical compens­a­tions were built into the fonts. Char­ac­ters inten­ded for use in small sizes typic­ally show an increased width and x-height, reduced stroke contrast and looser spacing.

In phototype, size-specific adjustments were largely given up and single-master designs dominated. This practice was continued during the early years of digital type.

ATF Garamond at 6, 8, 10, 12, 14, 16, 18, 24 and 72 pt

ATF Garamond, from left to right: 6, 8, 10, 12, 14, 16, 18, 24, 72 pt

Why we wrote this book

From the metal type era, hardly any docu­ment­a­tion on the subject is avail­able since punch­cut­ting, like other crafts, was not discussed much in writ­ing. The skills and insights were passed on from one master to the next by demon­stra­tion. Even today the design process of optic­ally sized typefaces has rarely been recor­ded or analysed. This lack of resource lead Tim Ahrens to research and write about it himself in 2007, in the hope that the outcome would become a useful source for prac­ti­tion­ers who wish to create fonts with size specific styles.

Features of this book

The book looks into type history and percep­tion psycho­logy, and analyses designs by old masters and numer­ous contem­por­ary design­ers. We inter­viewed a number of design­ers such as Robert Slimbach, David Berlow, Akira Kobay­ashi, and Chris­tian Schwartz. Their answers, along with the analysis of exist­ing fonts, form an import­ant basis for the prin­ciples explained in the book.

Size-specific adjustments to type designs, design advice

The most extens­ive section, “Design advice”, gives compre­hens­ive guid­ance to size specific designs based on inter­views with contem­por­ary design­ers as well as our analysis on contem­por­ary and old masters.

Size-specific adjustments to type designs, type specimen section

The type speci­men section shows various metal and digital designs. It includes the authors’ comments on each typeface and provides cross-refer­ences to other designs and the relev­ant prin­ciples in the main part of the book.

About the new edition

The original version of this paper was written as part of Tim Ahrens’ MA in Typeface Design at the University of Reading in 2007. The follow­ing year, it was published by Mark Batty Publish­er. This first edition was produced as print-on-demand, which regret­tably resul­ted in a very high unit price and restric­ted produc­tion qual­ity. In 2013 we obtained the publish­ing rights and, since we have been constantly receiv­ing requests for the book, decided to update, extend, and re-publish it ourselves.

This 2014 edition is co-authored by Shoko Mugikura, who joined extend­ing and updat­ing the content and designed the book.

For more about the difference from the previous edition read our blog entry.

Sample sections on Suppression and emphasis of features in typeface design and on Spatial frequencies can also be found on our blog.


“As tech­no­logy for render­ing text on screen evolves, and the dream of dynamic optical scaling on the OS or browser level finally comes true, this book will be an import­ant guide for prepar­ing typefaces that will take advant­age of this in an informed and delib­er­ate way. Future gener­a­tions of type design­ers are very lucky to have a resource like this book, rather than having to cobble together the know­ledge wherever they can find it.”

“It is reas­sur­ing to look through the wide variety of approaches to optical scaling shown in speci­mens in the final section, and see that there isn’t one perfect solu­tion that we’re all working towards, but rather a range of correct answers, each appro­pri­ate to its own situ­ation and tech­no­lo­gical limit­a­tions.”

from the foreword by Christian Schwartz

“Des­pite the special­ized topic, this stuff is valu­able even to those who will never sketch a letter or fire up a font edit­or. Those who choose and use type in any capa­city will benefit from what this book has to offer. In discov­er­ing the ways that type can be optim­ized for specific applic­a­tions, readers will learn a lot more about vari­ations in letter­shape, stroke contrast, propor­tions, and spacing than nearly any other text can teach.”

Stephen Coles on Typographica

“While this book is aimed more towards type design­ers, the mater­ial fills in a lot of the gaps in prac­tice for typo­graph­ers quite nicely too. […] This is an insight­ful read behind the tools design­ers make (and use) every­day, and not to be missed.”

Jason Santa Maria

“This is not just the best, but really the only sig­nif­i­cant work on this intrigu­ing and com­plex topic. Highly rec­om­men­ded for inter­me­di­ate and advanced type design­ers, and any­one else inter­ested!”

Thomas Phinney on the FontLab blog

Table of contents

Notes on this edition


1 Introduction

2 Reasons for size-specific adjustments

Technological restrictions / Legibility and visual consistency / Purpose-specific designs / The situation today

3 Goals, methods, and structure of this book

3.1 Objective of this book

3.2 Research methods

History / Perception psychology / Concrete statements made by designers and writers / Analysis of existing fonts

4 History

4.1 Metal types

Hand punchcutting / The role of the punchcutter / Machine punchcutting / Ink spread / What is the “true” shape?

4.2 Phototypesetting

4.3 Digital fonts

Digital typesetting / Pixel fonts and hinting / Post-pixel screen typography

5 Perception psychology and reading research

The reduction phenomenon / Acuity of human vision / Spatial frequencies / Frequency channels / Adaptation / Crowding

6 Design advice

6.1 Letter shapes

Weight / Stroke contrast / Width / Vertical proportions / Counters / Suppression and emphasis of features / Serifs / Joins / Sans serifs / Large sizes

6.2 Spacing

6.3 Progression of shape

Order in which the masters are designed / Number of necessary masters / Interpolation as a design tool

7 Alternatives to optical sizes

Making a compromise / Accepting chunkiness in large sizes / Adding refined detail to robust general shapes / Using different designs altogether / Conclusion

8 Summary and outlook

9 Type specimens

10 Questionnaire




Title: Size-specific adjustments to type designs – An investigation of the principles guiding the design of optical sizes
Authors: Tim Ahrens and Shoko Mugikura
Published by: Just Another Foundry
Format: 200 × 300 mm
192 pages
Printing: offset, 2-colour
Binding: OTA binding
ISBN: 978-3-00-045937-5

This book is currently out of print.

If you wish to receive a notification in case a reprint or a revised edition becomes available, please send a message