by the book

Cultural  

1. According to established rules: “The inspector will be visiting the factory today, so let's make sure we do everything by the book.”

---

by the book Idioms  

1. Strictly according to the rules, as in Our trip leader is going by the book, allowing us to wander off only for short periods. Shakespeare already used the term figuratively in Romeo and Juliet (1:5): “You kiss by the book.” Also see by the numbers.

---

Example Sentences

A balanced portfolio in your mid-70s means allocating 40% to 50% to bonds, if you’re playing your septuagenarian retirement planning by the book.

From MarketWatch • Jun. 2, 2026

There is a second, diffuse—seemingly unintentional—sadness revealed by the book that is something closer to cultural or civilizational loss.

From The Wall Street Journal • Feb. 23, 2026

"If you look at the actions of Franco Mostert and Lood de Jager the previous week, he has done everything by the book," added backs coach Stick, 41.

From BBC • Nov. 18, 2025

Tonga coach Kristian Woolf defended the team doctors, saying everything was "done by the book".

From Barron's • Nov. 3, 2025

De Magnete had a direct influence on Galileo, who was inspired by the book to carry out his own investigations of magnetism, and who described Gilbert as the founder of the experimental method of science.

From "The Scientists" by John Gribbin

Related Words

• binding
• demanding
• draconian
• exacting
• forceful
• harsh
• inflexible
• ironclad
• rigorous
• severe
• stiff
• strict
• tough