Per identifies the instrument, means, method, channel, or intermediary used to accomplish an action. Its central question is per kio?—“by means of what?” English distributes this meaning across with, by, via, through, and using, so choosing per requires attention to the role, not the English word.
Physical instruments
Use per for an object deliberately used as a tool.
Mi malfermis la pakaĵon per tondilo, ĉar mi ne trovis tranĉilon.
I opened the package with scissors because I couldn't find a knife.
Ŝi mezuris la muron per malnova mezurbendo.
She measured the wall with an old tape measure.
Ĉu oni povas pagi per karto ĉi tie?
Can one pay by card here?
The object after per is not the thing acted on. In the first example, the package is the direct object and tondilo is the instrument. Because the preposition already marks that role, the complement remains without -n: per tondilo, never per tondilon.
Means, methods, and transport
The “tool” need not be a handheld object. A transport system, language, technique, or procedure can be the means.
Ni venis per trajno kaj revenos per buso.
We came by train and will return by bus.
La teamo solvis la konflikton per longa kaj sincera interparolo.
The team resolved the conflict through a long and honest conversation.
Bonvolu respondi per Esperanto, se tio estas oportuna por vi.
Please reply in Esperanto if that is convenient for you.
With transport, per trajno describes the means of travel. En la trajno locates someone inside the train; sur la trajno would literally place something on its surface. With language, per Esperanto presents Esperanto as the communicative medium. En Esperanto is also normal when the language is treated as the form in which a text or utterance exists. Thus paroli per interpretisto means speak through an interpreter, while paroli en Esperanto means speak in Esperanto.
Channels and intermediaries
Messages, payments, and services often pass through a channel or a person. Per highlights that middle link.
Mi sendos al vi la dokumenton per retpoŝto ĉi-vespere.
I'll send you the document by email this evening.
Ni eksciis pri la ŝanĝo per komuna amiko.
We learned about the change through a mutual friend.
— Kiel vi trovis tiun loĝejon? — Per retejo por luantoj.
— How did you find that apartment? — Through a website for renters.
Pere de makes the intermediary reading especially explicit: Ni interparolis pere de interpretisto “We spoke through an interpreter.” It is a transparent expression built from pere plus de, and it is common in neutral and formal writing. Plain per interpretisto is often shorter and equally clear.
Per versus kun
English with hides a crucial distinction. Kun marks accompaniment, association, or a co-participant; per marks the means used.
Mi iris al la laborejo kun Marta per ŝia aŭto.
I went to the workplace with Marta in/by means of her car.
Marta accompanied me, so she follows kun. Her car supplied the transport, so it follows per.
Li manĝis la supon per kulero kun siaj kolegoj.
He ate the soup with a spoon together with his colleagues.
La knabo skribis per blua krajono, sed lia fratino skribis kun li.
The boy wrote with a blue pencil, but his sister wrote alongside him.
Some contexts allow different construals. Kafo kun lakto describes coffee accompanied or mixed with milk; milk is not a tool used to drink the coffee. Kovri la tablon per tuko presents the cloth as the material used to cover it. The right preposition follows the semantic role.
Agent versus instrument in passive clauses
In a passive clause, de normally identifies the agent or source of the action, while per identifies the instrument or means.
La fenestro estis rompita de la ŝtelisto per peza ŝtono.
The window was broken by the thief with a heavy stone.
La artikolo estis tradukita de Ana per komputila tradukilo, poste zorge reviziita.
The article was translated by Ana using a computer translation tool, then carefully revised.
The person performs the action; the stone or program enables it. English uses by for both de and some uses of per, but Esperanto keeps the roles distinct. The page on Agents with De develops the passive contrast.
With an agentless passive, a per phrase can remain because an instrument does not have to be a conscious actor:
La temperaturo estas aŭtomate regata per sensiloj.
The temperature is automatically controlled by means of sensors.
Per versus cause and purpose
Per answers “by what means?” Pro answers “because of what cause or motive?” Por answers “for what intended goal or beneficiary?” A single situation may contain all three.
Pro la pluvo ni mendis manĝon per aplikaĵo por la gastoj.
Because of the rain, we ordered food through an app for the guests.
The rain caused the decision (pro), the app was the channel (per), and the guests were the intended beneficiaries (por).
Ŝi lernas per ĉiutaga praktikado por labori eksterlande.
She learns through daily practice in order to work abroad.
Daily practice is the method; working abroad is the intended goal. This difference is why English by studying and to work cannot both be translated with the same preposition.
Resulting manner and per si mem
In established usage, per can introduce an action or state that characterizes how something happens: morti per natura morto “die a natural death.” Contemporary prose often prefers an adverb when it is shorter: morti nature. This action-repeating use is grammatical but less central than instrument and means.
The fixed expression per si mem means “by itself/through its own effect,” without outside assistance.
La problemo ne solviĝos per si mem; ni devas decidi hodiaŭ.
The problem won't solve itself; we must decide today.
Do not confuse it with reflexive object sin. In per si mem, si follows a preposition and refers back to the third-person subject; mem adds emphasis.
Useful derivatives
The same root produces a small, useful family:
| Form | Meaning | Register/use |
|---|---|---|
| pere de | through, by way of | neutral; stresses an intermediary |
| senpere | directly, without an intermediary | neutral |
| peri | mediate, arrange through an intermediary | neutral/formal |
| peranto | intermediary, mediator | neutral |
| perlabori | earn through work | neutral |
La agentejo peris kontakton inter la familio kaj la posedanto.
The agency arranged contact between the family and the owner.
Se eble, mi preferas aĉeti rekte de la produktanto, ne pere de peranto.
If possible, I prefer to buy directly from the producer, not through an intermediary.
These derivatives are not substitutes in every per phrase. Use the simple preposition for an ordinary instrument or means.
Common Mistakes
1. Translating every English “with” as kun
❌ Mi tranĉis la panon kun akra tranĉilo.
Incorrect for the intended instrument reading — kun presents accompaniment rather than the tool.
✅ Mi tranĉis la panon per akra tranĉilo.
I cut the bread with a sharp knife.
2. Adding -n after per
❌ Ŝi pagis per kreditkarton.
Incorrect — the preposition already marks the instrument.
✅ Ŝi pagis per kreditkarto.
She paid by credit card.
3. Marking a passive agent with per
❌ La letero estis verkita per la direktoro.
Incorrect for 'written by the director' — the director is the agent, not an instrument.
✅ La letero estis verkita de la direktoro.
The letter was written by the director.
4. Confusing cause with means
❌ La matĉo estis nuligita per la neĝo.
Incorrect — the snow caused the cancellation; it was not a tool deliberately used.
✅ La matĉo estis nuligita pro la neĝo.
The match was canceled because of the snow.
Key Takeaways
- Per marks a tool, method, vehicle, channel, or intermediary.
- Its complement does not take -n.
- Contrast per means, kun accompaniment, de passive agent, pro cause, and por purpose.
- Pere de, senpere, peri, and peranto preserve the idea of an intermediate means or link.
Now practice Esperanto
Reading grammar gets you part of the way. The exercises are where it sticks — free, no signup needed.
Start learning Esperanto →Related Topics
- KunB1 — Use kun for accompaniment and associated circumstances, while distinguishing companions from instruments, topics, and opponents.
- DeA2 — Use de for movement or development away from a source and for relationships such as possession, authorship, composition, time, and passive agency.
- PorB2 — Use por for an intended beneficiary, purpose, use, result, exchange, or the goal toward which an action is directed.
- ProB2 — Use pro for cause and motive, while distinguishing reasons from purposes and recognizing traditional exchange uses.
- Agents with DeB2 — Use de to identify the semantic doer of a passive participle, while distinguishing agents from sources, instruments, and experiencers.
- No Accusative after Ordinary PrepositionsA1 — Learn why ordinary Esperanto prepositions take unmarked complements and how to distinguish them from directional and exceptional combinations with -n.