Size-specific adjustments to type designs

An investigation of the principles guiding the design of optical sizes

Purpose of the book Quotes Table of contents Featured typefaces Order

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

“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

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