When I first tried to improve my English writing, I remember the confusion that occurs when you must choose the proper usage of phrases like “by which” and “in which.” Even advanced speakers struggle, because the grammar behind these phrases depends on the context, the tense, and the structure of the sentences you are constructing.
In my own work, whether I was preparing an academic report or a business document, I noticed how the purpose of a phrase refers to the situation, the environment, or the method through which something happens. This simple shift helped me become more fluent, and it also gave me clarity, because it highlights the means and the places where an action takes place.
Over time, I began exploring the more subtle differences, and that journey provides the knowledge that many learners look for when they try to distinguish expressions that look similar but behave differently. I kept a small notebook to guide myself, and I would cut through the rules by writing one example after another, especially in real-life situations—like the room where we met, the system by which people vote, or the ways we talk about something in daily communication. I noticed how prepositions shape the message and improve the accuracy of your writing, and the more I practiced, the more the whole process felt less daunting.
As I kept mastering these patterns, I realized that good writing also comes from the ability to link ideas effectively and stay focused on the point you want to make. The language becomes clearer when you know how to use each method of expression with precision, and this enhances your overall professional level. My early attempts didn’t always look correct, and some of them only appears right until I read them with fresh eyes, but with time I learned to be more knowing and more aware of the ways these forms shape meaning.
I also learned that every writer, including me, goes through moments of scratching their heads as they move between new ideas, but this is just part of the learning curve. I worked depending on simple steps: selecting the right clauses, following the rules, and practicing again and again until the whole idea felt simple and natural. When I look back, I see that the landscape of English grammar is vast, and each word or phrase helps you unlock another layer. Once you understand how these patterns work, you will not only write more confidently but also sound more professional in every situation, whether formal or casual.
If you stay patient and keep practicing, you will find that even a challenge like this one becomes a skill you can rely on, because the more you use it, the stronger your control of it becomes.
What ‘By Which’ Actually Means (Keyword: By Which Usage)
When you use “by which”, you’re describing the method, mechanism, process, or means through which something happens. It answers the question “how?” rather than “where?” or “in what situation?”
Think of “by which” as connecting an action to the tool or process that makes it possible.
Breaking It Down
- By = preposition showing method or means
- Which = relative pronoun referring to a specific noun
Together, they explain how something happens.
Everyday Examples
- “He presented the system by which the company tracks employee performance.”
→ method: the system enables the tracking- “She discovered a technique by which the material becomes waterproof.”
→ mechanism: the technique causes waterproofing
Quick Meaning Table
| Phrase | Meaning | When It Fits | Example |
| By which | method, mechanism, cause, means | When describing how something works | “The algorithm by which results are sorted is updated daily.” |
A Fast Test
Ask yourself:
“Am I explaining a method or mechanism?”
If yes, ‘by which’ is the correct choice.
What ‘In Which’ Actually Means (Keyword: In Which Meaning)
You use “in which” when referring to a location, setting, situation, environment, or context. It answers “where?” or “in what circumstance?”
Structure
- In = preposition showing place or contex
- Which = relative pronoun referring to a specific noun
This means “in the place or situation that…”.
Examples That Show Real Meaning
- “The folder in which the documents were stored has been deleted.”
→ location: folder- “The meeting in which the policy was discussed ran longer than expected.”
→ context: meeting
When Writers Choose It
You’ll find “in which” in:
- academic writing
- legal contracts
- business reports
- technical documentation
It sounds formal, but it’s accurate.
Meaning Table
| Phrase | Meaning | When It Fits | Example |
| In which | place, context, situation, condition | When describing where something happens | “The environment in which the plants grow affects their size.” |
A Fast Test
Try replacing it with “where”.
If the sentence still makes sense, “in which” is likely correct.
When ‘Where’ Works Better Than Either Phrase (Keyword: Where vs In Which)
Sometimes, “where” is the friendliest, cleanest option. Because where functions as both an adverb and a conjunction, it feels natural in conversational writing and storytelling.
Where Feels Natural When Talking About:
- physical locations
- figurative spaces (areas of study, chapters, topics)
- situations that can be imagined as “places”
Examples
- “The town where I grew up sits near the mountains.”
- “The chapter where she explains the theory is my favorite.”
You could say “in which” but it feels stiff:
- “The town in which I grew up…” (formal)
- “The chapter in which she explains…” (formal)
A Simple Rule
Use “where” when:
- speaking casually
- describing a physical or metaphorical “place”
- creating smoother flow
Use “in which” when:
- writing formally
- describing non-physical contexts (laws, arguments, protocols)
Cases Where You Should Not Use “Where”
You can’t replace in which with where when describing:
- time
- states of being
- abstract ideas not imagined as places
Example:
- “The year in which the law passed…” → “The year where the law passed…” (incorrect)
Clarifying ‘Wherein’ and Why It Sounds Old-Fashioned (Keyword: Wherein Meaning)
Wherein is the formal, old-fashioned cousin of in which. You see it in:
- legal documents
- contracts
- historical writing
- religious texts
It means “in which”, but it carries a heavier, more solemn tone.
Examples
- “The contract, wherein both parties agree to the terms, remains valid.”
- “A world wherein justice prevails has long been humanity’s dream.”
Why Most Writers Avoid It Today
- It feels archaic
- It slows reading flow
- It makes writing sound overly formal
Still, it works when you want gravitas or tradition.
Fast Rule
When in doubt, choose “in which” over “wherein”.
How to Decide Between ‘By Which’ and ‘In Which’ Instantly
Here’s a simple decision tool to eliminate confusion forever.
Decision Framework Table
| If You’re Describing… | Use | Question to Ask | Example |
| Method / mechanism / process | By which | “Am I explaining how something happens?” | “The tool by which we measure pressure is calibrated weekly.” |
| Location / context / situation | In which | “Am I explaining where something happens?” | “The room in which the ceremony takes place seats 400.” |
Decision Diagram (Text Version)
Does your sentence explain how something works?
→ Yes → Use “by which”
→ No →
Does your sentence describe a place, situation, or context?
→ Yes → Use “in which”
→ No → consider “where,” “through which,” or rephrasing
Quick Swap Test
Try replacing the phrase with a keyword:
- If “method” fits → use by which
- If “place/context” fits → use in which
Example:
“The rule ___ the process is defined…”
- method → by which
- context → in which
Comparative Examples to Make the Differences Clear
This section removes any remaining confusion by showing side-by-side examples.
Comparison Table
| Meaning | By Which | In Which | Why |
| Method vs location | “The method by which data is encrypted is highly secure.” | “The system in which data is stored is outdated.” | The first describes a mechanism, the second a context. |
| Cause vs situation | “The accident by which the damage occurred…” | “The situation in which he found himself…” | Cause vs context. |
| Process vs environment | “The formula by which results are calculated…” | “The environment in which calculations occur…” | One explains how, the other where. |
| Means vs setting | “The tool by which photos are edited…” | “The platform in which photos are organized…” | Instrument vs location. |
Expanded Examples
These examples show deeper nuance:
- “The framework by which the court interprets the law has changed.”
→ method: interpretive framework - “The jurisdiction in which the case is tried affects the outcome.”
→ context: legal jurisdiction - “The technique by which athletes improve endurance varies.”
→ mechanism - “The atmosphere in which the debate unfolded was tense.”
→ situation
Common Mistakes Writers Make (and Simple Fixes)
Even experienced writers get tripped up by these phrases. Here are the most frequent errors and clear fixes.
Mistake 1: Using ‘By Which’ When No Method Exists
“The room by which the ceremony took place…”
“The room in which the ceremony took place…”
Mistake 2: Using ‘In Which’ When Describing a Process
“The steps in which the machine filters water…”
✔ “The steps by which the machine filters water…”
Mistake 3: Using ‘Where’ in Strictly Formal Writing
You can’t always replace in which with where, especially in legal or academic sentences.
“The clause where exceptions are allowed…”
“The clause in which exceptions are allowed…”
Mistake 4: Overusing These Phrases
Sometimes, it’s better to rewrite the sentence entirely.
Instead of:
- “The system in which changes are made…”
Try: - “The system lets users make changes…”
This keeps writing light and direct.
Read More: There Have Been or Has Been? Master It Once and for All!
Advanced Usage Notes for Professional Writers
If you write research papers, policy briefs, contracts, or long-form analysis, precision matters even more. Here are deeper insights rarely covered by typical grammar guides.
How Tone Changes With Phrase Choice
| Phrase | Tone Level | Best Use Cases |
| By which | formal, technical | scientific writing, law, engineering |
| In which | moderately formal | essays, reports, contracts |
| Where | conversational | blogs, fiction, personal writing |
| Wherein | archaic/formal | legal, religious, historic texts |
Why Technical Writers Prefer ‘By Which’
It clarifies cause-and-effect relationships.
Example:
“The equation by which velocity is determined…”
Using in which here would distort meaning.
Why Legal Writers Prefer ‘In Which’
Legal writing depends on precise contexts and settings.
Example:
“The jurisdiction in which the contract is enforceable…”
Academic Writing Tip
Academics switch between:
- in which (formal analysis)
- where (to simplify complex ideas)
Example:
“In the model in which variables interact…”
vs.
“A stage where both conditions exist…”
Summary Chart for Quick Reference
| Phrase | Use When Referring To | Easy Test | Example |
| By which | method, process, mechanism | Replace with “method” | “The system by which results are produced…” |
| In which | place, context, situation | Replace with “where” (if appropriate) | “The department in which he works…” |
| Where | literal or figurative place | Sounds natural in speech | “The city where I studied…” |
| Wherein | extremely formal “in which” | Use for old-fashioned tone | “A world wherein equality is universal…” |
Case Studies: How Real Writers Choose the Right Phrase
These short case studies show how context determines the best choice.
Case Study: Business Report
A manager writes:
“The system by which clients are billed needs an overhaul.”
Why by which?
Billing requires a method, not a location.
Later in the same report:
“The department in which billing errors occur most often…”
This describes a context, not a method.
Case Study: Academic Research
A researcher writes:
“The study explores the framework in which cultural norms develop.”
Context → in which
But when describing a model:
“The mechanism by which social values are transmitted…”
Process → by which
Case Study: Legal Contract
A clause reads:
“The venue in which disputes will be resolved…”
Formal setting → in which
Another clause:
“The procedure by which claims may be filed…”
Method → by which
Quote From a Writing Coach
“If you can imagine a place, use ‘in which.’
If you can imagine a method, use ‘by which.’
If you want the sentence to breathe, use ‘where.’”
Conclusion
Understanding when to use “by which” and “in which” is really about knowing the role each phrase plays in a sentence. Once you see that one points to a method and the other points to a place or situation, everything starts to feel much easier. With a bit of practice, these patterns become familiar, and you’ll begin using them naturally in both writing and conversation. Keep noticing the tiny details in everyday English, and your confidence will grow without you even realizing it.
FAQs
1. What does “by which” actually mean?
It explains how something happens or the method used. Example: “the process by which data is stored.”
2. When should I use “in which”?
Use it for places, situations, or environments. Example: “the folder in which the files are saved.”
3. Can I replace these phrases with simpler words?
Often yes. “By which” can become “how,” and “in which” can become “where,” depending on the sentence.
4. Are these phrases formal?
They’re common in formal writing, but you’ll also see them in everyday English when clarity matters.
5. Why do learners confuse them?
Because both connect ideas and look similar, but they point to different types of information—method vs. place/situation.
