How to Say 'By' in French: Mastering Par, De, and the Nuances

The Essential Guide on How to Say ‘By’ in French

The Direct Answer: Par, De, and The Rule of Context

When learning how to say by in French, the most common translations you will encounter are the prepositions par and de. Selecting the correct one is entirely dependent on the context of the sentence, an aspect of grammar that often separates a confident speaker from a hesitant one. The preposition par is generally used to mean “by way of,” “through,” or to indicate the agent performing the action in a passive sentence. Conversely, the preposition de is required for many passive constructions involving emotions or descriptions, as well as several fixed expressions. A quick review of French prose will confirm that the usage is nuanced, demanding attention to the specific grammatical function of “by” in English.

Why Context is Key to French Grammar Expertise

This comprehensive guide is designed to transform your uncertainty into expertise by dissecting the English word “by” into its five core functional uses. By focusing on the role “by” plays in your English sentence—whether it denotes means, agency, measurement, location, or time—you can confidently select the precise French translation every single time. This approach ensures not only grammatical correctness but also the clarity and authenticity that is the hallmark of genuine language mastery.

Using ‘Par’: The Rule for Agents, Means, and Proximity

Understanding when to use the preposition par is foundational to correctly translating “by” in French. In the simplest terms, par serves three primary roles: indicating the agent (the person/thing doing the action), the means (the method used), or movement through (a location or intermediary). When you encounter the English word “by” and can substitute it with “by way of,” “through,” or “via,” par is almost always the correct choice.

When ‘By’ Means ‘Through’ or ‘Via’ (Method/Means)

The most frequent application of par is to express the method, channel, or means by which an action is carried out. This is highly common in daily speech, and getting this right will immediately elevate your French proficiency.

Specifically, use par when “by” indicates:

The means of communication: If you communicate by phone (par téléphone), by email (par e-mail), or by chance (par hasard), the preposition is par.
A means of movement or transportation: If you travel by car (par voiture), by train (par train), or simply pass by a place (passer par le parc).

Expert Insight: According to the Larousse French-English Dictionary, par is the necessary choice when translating “by” to indicate a means or intermediary, particularly with transitive verbs that require an object to complete their meaning (e.g., envoyer (to send) par la poste). This emphasis on par for direct means ensures grammatical authority in your writing.

The Passive Voice Rule: Identifying the Agent of an Action

In grammar, the passive voice construction is crucial for identifying the correct use of par versus de. When a sentence uses the passive voice (e.g., “The book was written by the author”), the entity performing the action is called the agent.

In French, the agent of the action in the passive voice is introduced by the preposition par.

Example: The letter was written by the student $\rightarrow$ La lettre a été écrite par l’étudiant.
Example: The bridge was built by the Romans $\rightarrow$ Le pont a été construit par les Romains.

This rule establishes a direct connection between the action and the one responsible for it. However, as the next section will explore, this rule has a critical exception when the passive verb expresses an emotion or description, which often switches the preposition from par to de.

Mastering ‘De’: The Translation for Passive and Descriptive Usage

The Critical Distinction: ‘De’ for Descriptive and Emotional Passives

While par introduces the agent of a physical action in the passive voice (the “doer”), the preposition de steps in when the passive construction involves a descriptive state, emotion, or a non-physical action. This is a critical nuance for achieving native-level accuracy.

For example, when you want to say someone is “surprised by the news,” you would use surpris de la nouvelle. Other common emotional states follow this pattern, as the French preposition de here indicates the cause or source of the state rather than an active agent. This usage is common with verbs that convey a state of being rather than a completed action, ensuring your language sounds natural and experienced to native speakers.

To build authority in your French, it is essential to internalize which verbs favor which preposition in the passive voice. Based on usage frequency data compiled by leading French grammarians, here is a helpful comparison of common passive constructions:

Verb Type	Preposition	Example French	Example English
Action-Oriented (Agent)	Par	aimé par (loved by)	The book was read by her.
Action-Oriented (Agent)	Par	écrit par (written by)	The song was sung by him.
State/Description (Cause)	De	couvert de (covered with/by)	The floor was covered with water.
State/Description (Cause)	De	rempli de (filled with/by)	She was filled with joy.

When ‘By’ Follows a Quantity or Measurement

The preposition de is also the correct choice when “by” is used to express a specific measure, difference, or quantity. You will use de to denote the amount of increase or decrease.

For instance, if you are discussing statistics or finance and need to say something “increased by 10%,” the correct French phrasing is augmenté de 10%. This rule applies universally to any numerical measurement of change, whether it’s a difference in temperature, cost, speed, or height. This usage establishes credibility by correctly handling formal, data-driven statements. Always use de after verbs and adjectives indicating a change in value, such as diminuer (to decrease), réduire (to reduce), or plus (more).

Phrases for Location and Time: ‘By’ as ‘Near’ or ‘Before’

When you use the word “by” to indicate proximity or a deadline, the established French translation rules change completely. In these instances, you must abandon the common translations of par or de and pivot to specialized prepositions to maintain accuracy and native flow. Understanding these nuances is critical for conveying the correct spatial and temporal relationships in your speech and writing.

Translating ‘By’ as a Location: Près de vs. À Côté de

To effectively express “by” meaning “near” or “beside” in French, you must use the set phrases près de (near, close to) or à côté de (next to, beside). Par is incorrect in this context and can lead to significant confusion.

For example, if you want to say, “The house is by the river,” the correct translation is La maison est près de la rivière. Similarly, “Can you sit by me?” becomes Peux-tu t’asseoir à côté de moi? Using par in this context is one of the most common errors novice speakers make.

Consider the following quick example: if you attempt to translate “I passed by the window” as Je suis passé par la fenêtre, you are literally saying, “I passed through the window” (implying you broke or went through it), which is likely not your intended meaning. The correct phrase for merely passing near the window is Je suis passé près de la fenêtre. This linguistic difference highlights the importance of choosing the correct preposition to convey the intended meaning accurately.

Translating ‘By’ as a Deadline: D’ici vs. Avant

When “by” functions as a temporal marker indicating a deadline or a point in time before an action must be completed, it translates most often to d’ici or avant.

Avant means “before” and is used when you are emphasizing the necessity of completing the action before the specified date or time. Example: Please send the report by Friday translates to Veuillez envoyer le rapport avant vendredi.
D’ici means “by the time of” and often implies a timeframe leading up to a date or event. Example: I will be home by 5 p.m. translates to Je serai à la maison d’ici 17 heures.

In both cases, using par or de would be inappropriate and would confuse your deadline, demonstrating the expertise required to correctly use French prepositions for time-based phrases.

Advanced Usage: Essential French Expressions with ‘By’

Moving beyond the core rules of par and de allows you to sound more natural and fluent. French, like any language, relies heavily on idiomatic expressions and set phrases where the simple preposition rules break down. Mastery of these is a hallmark of authoritative knowledge in the language.

Sequence and Progression: ‘By’ as ‘One After the Other’

When ‘by’ is used to show a sequence, progression, or distribution—such as one by one or day by day—the French translation often involves a repetition of nouns connected by prepositions, primarily par or après.

For example, to express a distribution or a simple division, par is frequently used:

One by one: Un par un
Two by two: Deux par deux

However, when indicating a chronological or sequential progression, après (after) is common, sometimes paired with de:

Day by day: De jour en jour (often used for gradual change) or jour après jour (more literal sequence).
Step by step: Étape par étape (a key phrase to memorize).

This nuanced usage is an indicator of deep expertise in French grammar, as it distinguishes native phrasing from literal, awkward translations.

Mental Shortcuts: Common Idioms and Set Phrases

Many of the most common uses of ‘by’ in English translate to fixed, non-deducible French idioms. Attempting to apply the standard rules for par or de in these situations will almost always lead to an incorrect and confusing translation. To speak with confidence and authority, these must be committed to memory.

English Idiom	French Translation	Literal Meaning/Context
By heart	Par cœur	Literally “by heart”
By accident	Par accident	Using par to denote the means
By chance	Par hasard	Using par to denote the means
By law	Selon la loi	Selon (according to) is preferred
By the way	Au fait or D’ailleurs	Completely different structure

Learning these fixed phrases is the final step toward truly experiential fluency. To solidify your experience with the correct pronunciation and intonation, which is vital for communicating these common phrases, practice with an audio guide. [External Link for Audio Guide: A link to an audio resource demonstrating the pronunciation of ‘par cœur’, ‘par accident’, ‘par hasard’, ‘au fait’, and ‘d’ailleurs’ would be integrated here.]

Your Top Questions About French Prepositions Answered

Q1. Which French preposition is used for ‘step-by-step’?

For the common phrase “step-by-step,” the French translation is the fixed phrase “étape par étape”, which uses the preposition par. This structure is used to express a methodical, sequential progression. Other sequential phrases often follow a similar pattern, such as jour par jour (day by day).

Q2. What is the rule for translating ‘by’ when referring to transport?

When expressing “travel by” a certain mode of transport, the rules are highly specific and often bypass par or de entirely. This nuance is crucial for demonstrating authority and expertise in French usage. The general rule is:

Use en for most enclosed or motorized means of transport:
- en voiture (by car)
- en train (by train)
- en avion (by plane)
- en bus (by bus)
Use à for means of transport where you are exposed or riding on something, and for walking:
- à vélo (by bicycle)
- à moto (by motorcycle)
- à cheval (by horse)
- à pied (by foot/walking)

Crucially, you should NOT use par for these everyday situations. For example, saying “par voiture” is generally considered incorrect for “traveling by car.” The exception where par is used for transport is in formal, official declarations or when specifying a route (e.g., expédié par avion - shipped by plane), which, according to the Dictionnaire de l’Académie française, retains its meaning of “by way of” or “through a channel.” Mastering this distinction is a clear indicator of language expertise.

Mode of Transport	Correct French Preposition	Example Sentence
Car, Bus, Train, Plane	en	Je voyage en train. (I travel by train.)
Bike, Foot, Horse	à	Elle va au travail à vélo. (She goes to work by bike.)
Shipping/Formal Route	par	Le colis est envoyé par* bateau.* (The package is sent by boat.)

Final Takeaways: Mastering French Prepositions in Conversation

Summarize the 3 Key Actionable Steps for Choosing Par vs. De

For those aiming to achieve fluency and sound genuinely native, mastering the subtle difference between par and de when translating “by” is essential. The simplest, most effective guideline is this: Use Par for the agent, the means, or the method of an action; use De for description, quantity, or emotional states. For instance, a letter is written par the author (agent), but you are surprised de the news (emotional state). Furthermore, to build authority and trust in your speaking, always double-check set phrases and locations, entirely avoiding par when it means “near” or “next to”—instead, rely on près de or à côté de.

What to Do Next: Practice with Contextual Examples

The best way to solidify your understanding and move toward fluent speech is to immediately review and practice a sample conversation that uses all five contexts of “by.” This demonstrated experience in applying the rules will help move them from theoretical knowledge to natural, conversational usage, ensuring you select the correct preposition every time.