Esperanto can mark a bare expression of weight, size, amount, or price with -n. In La valizo pezas dek kilogramojn, the suitcase does not act on “ten kilograms”; that phrase measures its weight. The form resembles a direct object, but its function is to answer questions such as “how much?”, “how heavy?”, or “at what price?”
Weight, size, and quantity as complements
After a verb that describes a measurable property, the quantity commonly takes -n. Typical verbs include pezi “weigh,” mezuri “measure/have dimensions,” larĝi “be wide,” and valori “be worth.”
Mia valizo pezas dek ok kilogramojn, do mi ne devos krompagi.
My suitcase weighs eighteen kilograms, so I won't have to pay extra.
La tablo mezuras du metrojn laŭlonge kaj unu metron laŭlarĝe.
The table measures two meters lengthwise and one meter widthwise.
Ĉi tiu botelo entenas unu litron da akvo.
This bottle contains one liter of water.
The last example requires a useful distinction. With enteni, unu litron da akvo can be analyzed as the direct object—the contents—rather than merely as an adjunct measure. The visible -n does not tell you by itself which function is present. Meaning and verb valency do. This is why “anything after a verb with -n is an object” is not a workable rule.
Measurements also modify adjectives. The measure tells to what degree the quality applies.
La pakaĵo estas tridek kilogramojn peza; ni bezonos du homojn por levi ĝin.
The package weighs thirty kilograms; we'll need two people to lift it.
Ni mendis du metrojn longan tablon por la manĝoĉambro.
We ordered a two-meter-long table for the dining room.
In the second sentence, du metrojn measures longan. The adjective longan and the noun tablon take -n because tablon is the object of mendis. Different layers of the phrase happen to carry the same ending for different reasons.
Price after kosti and value after valori
With kosti “cost,” the thing being priced is normally the subject and the price is a measure complement in -n.
For the formation and reading of currency amounts themselves, see money and prices.
La bileto kostas dek du eŭrojn, inkluzive de la rezervokotizo.
The ticket costs twelve euros, including the booking fee.
Kiom kostis la riparo? — Ĝi kostis preskaŭ kvincent eŭrojn.
How much did the repair cost? — It cost almost five hundred euros.
La malnova horloĝo valoras pli ol mil eŭrojn, sed ŝi ne volas vendi ĝin.
The old clock is worth more than a thousand euros, but she doesn't want to sell it.
The price is not a direct object: dek du eŭrojn cannot become the subject of a passive version of La bileto kostas dek du eŭrojn. It quantifies the cost or value.
The question word kiom is an invariant correlative ending in -om. It does not accept accusative -n. This is not optional variation: the standard form is Kiom ĝi kostas?, never Kiomn. In a full answer, an eligible noun such as eŭroj receives -n.
— Kiom valoras tiu pentraĵo? — La posedanto petas dudek mil eŭrojn.
— How much is that painting worth? — The owner is asking twenty thousand euros.
Here dudek mil eŭrojn is the direct object of petas (“asks for/demands”), while the omitted answer to valoras would be a measure. Again, the same surface case can reflect distinct structures.
Cost versus exchange price
Esperanto can also introduce an exchange price with por. Because por is a preposition, its complement remains unmarked.
Mi aĉetis la jakon por kvindek eŭroj.
I bought the jacket for fifty euros.
La jako kostis kvindek eŭrojn.
The jacket cost fifty euros.
These sentences report the same transaction from different grammatical viewpoints. In the first, la jakon is the object purchased and por kvindek eŭroj names what was given in exchange. In the second, la jako is the subject and kvindek eŭrojn measures its cost.
With pagi, the amount paid can function as the thing transferred and therefore as a direct object. A por-phrase can name what the payment obtains.
Ni pagis okdek eŭrojn por la vespermanĝo.
We paid eighty euros for the dinner.
It is pedagogically important not to force one semantic label onto every amount. After kosti, the price is a measure; after pagi, the money can be the verb's object. Both receive -n, but for different grammatical reasons.
Other ways to package a measurement
A bare measure complement is only one option. A noun can describe a measurement with de, or Esperanto can build a compound adjective.
La ŝnuro havas longon de dek metroj.
The rope has a length of ten meters.
Ni bezonas dekmetran ŝnuron por sekurigi la boaton.
We need a ten-meter rope to secure the boat.
La pezo de la pakaĵo estas ses kilogramoj.
The weight of the package is six kilograms.
In de dek metroj, the preposition blocks accusative marking on its complement. In dekmetran, the number and unit form a compound adjective, which then agrees with ŝnuron. In the last example, ses kilogramoj is a predicative noun phrase after estas, so it remains unmarked.
Contrast that with a measure modifying an adjective:
La pakaĵo estas ses kilogramojn peza.
The package is six kilograms in weight.
Although both sentences describe the same reality, their structures differ. Ses kilogramoj identifies the value of the subject noun pezo; ses kilogramojn measures the degree of peza.
The alternative with je
The general preposition je can introduce a measure, especially when the expression cannot take -n, when it is long, or when je makes the relationship clearer.
Je kiom la nova modelo estas pli malpeza?
By how much is the new model lighter?
La prezo altiĝis je dek procentoj en unu jaro.
The price rose by ten percent in one year.
The form kiom cannot become kiomn, so je kiom supplies the missing relationship. With ordinary noun measures, -n is usually more compact: La nova modelo estas du kilogramojn pli malpeza.
La nova modelo estas du kilogramojn pli malpeza ol la antaŭa.
The new model is two kilograms lighter than the previous one.
Je is not a universal replacement that must appear before every number. It is an available role marker when the bare accusative is impossible or less clear.
Subjects and predicative values stay unmarked
Numbers and measurement units do not inherently demand -n. If the whole quantity is a subject, it remains nominative.
Du litroj sufiĉos por la tuta grupo.
Two liters will be enough for the whole group.
Cent eŭroj estas tro alta prezo por uzita seĝo.
One hundred euros is too high a price for a used chair.
Compare La seĝo kostas cent eŭrojn: there the amount measures kosti. Case follows syntax, not the mere presence of a unit or currency.
Common Mistakes
Omitting -n after kosti
❌ La nova baterio kostas kvardek eŭroj.
Incorrect — the bare price measure after kostas needs -n.
✅ La nova baterio kostas kvardek eŭrojn.
The new battery costs forty euros.
Adding -n after por
❌ Mi vendis la biciklon por ducent eŭrojn.
Incorrect — por is a preposition, so its complement is unmarked.
✅ Mi vendis la biciklon por ducent eŭroj.
I sold the bicycle for two hundred euros.
Trying to put -n on kiom
❌ Kiomn kostas sendo al Kanado?
Incorrect — kiom is invariant and cannot take -n.
✅ Kiom kostas sendo al Kanado?
How much does shipping to Canada cost?
Marking a subject quantity
❌ Kvin litrojn sufiĉas por plenigi la ujon.
Incorrect — five liters is the subject of sufiĉas.
✅ Kvin litroj sufiĉas por plenigi la ujon.
Five liters is enough to fill the container.
Confusing a predicative value with an adjective measure
❌ La pezo de la skatolo estas dek kilogramojn.
Incorrect — the quantity identifies the predicative value of pezo and remains unmarked.
✅ La pezo de la skatolo estas dek kilogramoj.
The weight of the box is ten kilograms.
Key Takeaways
- Bare measures after verbs such as pezi, kosti, and valori normally take -n.
- A price after kosti is a measure; money after pagi can be a direct object, even though both forms end in -n.
- Use por plus an unmarked amount for an exchange price, and je when a general measure marker improves clarity.
- Quantities used as subjects or predicative values remain unmarked: Du litroj sufiĉas; La pezo estas du kilogramoj.
Related Topics
- Distance and ExtentA2 — Use measure -n for distances traveled, physical dimensions, differences in extent, and offsets from a reference point.
- Time DurationA1 — Express how long an event lasts by marking a time measure with -n or by using an explicit duration phrase.
- Distance, Weight, and VolumeB1 — Measure dimensions, separation, weight, and capacity with unit nouns, accusative extent, je and de phrases, and da after quantities.
- Money and PricesB1 — State prices, values, payments, ranges, discounts, and per-unit rates with correct currency nouns, case, and verb frames.
- PorB2 — Use por for an intended beneficiary, purpose, use, result, exchange, or the goal toward which an action is directed.
- JeB1 — Use je for conventional clock-time, measure, body-part, and abstract relations when no more specific preposition expresses the intended role.