Spanish Rules Library

Spanish rules for humans. Structured for AI.

An independent, multilingual reference for Spanish grammar, verb conjugation, usage, and regional variation — read it as web pages, or consume the same source of truth as a JSON API and AI-readable Markdown.

347 rules published · 638 machine-verified conjugation tables

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Verbs

638 full conjugation tables, every form machine-verified →

Conjugation 55

Irregular conditionals: tendría, haría, diría

The conditional uses exactly the same twelve irregular stems as the future: tendría, pondría, saldría, diría, haría, podría, sabría, querría, vendría, valdría, cabría, habría.

Conditional: hablaría, comería, viviría

Infinitive + -ía, -ías, -ía, -íamos, -íais, -ían for all verbs: hablaría, comerías, vivirían. Used for hypotheticals, polite requests, and the future-in-the-past.

Irregular future stems: tendré, saldré, diré, haré

Twelve verbs use a shortened stem before the regular future endings: tener → tendr-, poner → pondr-, salir → saldr-, decir → dir-, hacer → har-, poder → podr-, saber → sabr-, querer → querr-, venir → vendr-, valer → valdr-, caber → cabr-, haber → habr-. The conditional uses the same stems.

A1, A2

The everyday future: ir a + infinitive

Voy a comer, vas a ver, vamos a salir: conjugated ir + a + infinitive is the default way to talk about the future in spoken Spanish.

B1, B2

Future of probability: serán las cinco

Spanish uses the future tense to guess about the present: ¿Qué hora será? Serán las cinco — 'It must be around five.'

Simple future: hablaré, comeré, viviré

One set of endings for all verbs, attached to the full infinitive: -é, -ás, -á, -emos, -éis, -án. Hablaré, comerás, vivirá.

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Grammar 143

Adjective agreement: gender and number

Adjectives match their noun: -o adjectives have four forms (rojo/roja/rojos/rojas); -e and most consonant adjectives have two (grande/grandes, fácil/fáciles).

Shortened adjectives: buen, gran, primer, algún

Bueno, malo, primero, tercero, alguno, ninguno, uno drop the -o before a masculine singular noun (buen día, primer piso); grande becomes gran before any singular noun.

Tan... como, tanto... como: comparing equals

Tan + adjective/adverb + como (tan caro como); tanto/a/os/as + noun + como (tanta paciencia como); verb + tanto como.

Más que, menos que: comparing unequals

Más/menos + adjective + que: más caro que, menos complicado que. Before numbers, que becomes de: más de cien.

Este, ese, aquel before nouns

Three distances agreeing with the noun: este libro, esa mesa, aquellos años. Ese also covers 'near you' and the recently mentioned.

Indefinite adjectives: alguno, cada, varios, cualquier

Algún/ningún (shortened before masc. sing.), cada (invariable), varios/as, otro (never with un), todo + article, cualquier before any noun.

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Usage & situations 48

Can: poder vs saber

Saber + infinitive = learned skill (sé manejar); poder = possibility, permission, or circumstance (hoy no puedo manejar). English 'can' covers both — Spanish splits them.

Accommodation: reservas, check-in, alquiler

Hotel: tengo una reserva a nombre de..., ¿a qué hora es el check-out?, ¿incluye desayuno? Renting: ¿cuánto es el alquiler?, ¿piden garantía?, expensas/servicios aparte.

Giving advice: deberías, yo que tú, te conviene

Deberías + infinitive; yo que tú / yo en tu lugar + conditional; te conviene + infinitive; te recomiendo que + subjunctive.

Agreeing and disagreeing

Agree: (estoy) de acuerdo, tenés razón, exacto, claro, eso. Disagree: no estoy de acuerdo, no lo veo así, sí, pero..., depende.

Apologizing: perdón, lo siento, disculpá

Perdón/disculpa for small bumps; lo siento (mucho) for real regret and bad news; fue sin querer (it was an accident); no va a volver a pasar.

Asking prices: ¿cuánto cuesta?, ¿a cómo?

¿Cuánto cuesta/vale? for items, ¿cuánto es? for totals, ¿a cómo (está)...? in markets, ¿en cuánto me lo deja? opens bargaining.

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Confusing pairs 28

Aquí/acá, allí/allá: the fine print

Aquí/allí mark precise points; acá/allá are looser zones and pair naturally with motion — and they're the dominant forms in much of Latin America, including the Southern Cone and Bolivia.

Bien vs bueno

Bien is an adverb (habla bien, estoy bien); bueno an adjective agreeing with nouns (un buen trabajo, una comida buena). Está bien = it's OK/fine.

Meeting: conocer, encontrarse con, quedar, reunirse

Conocer (preterite) = meet for the first time; encontrarse con = meet up / run into; quedar (con) = arrange to meet (Spain) — LatAm prefers quedamos en + time/place; reunirse = hold a meeting.

Deber vs deber de: must (duty) vs must (guess)

Deber + infinitive = obligation (debes llegar a las ocho); deber de + infinitive = probability (debe de estar durmiendo). Speech blurs it; writing shouldn't.

Este, ese, aquel: choosing the distance

Este = near me; ese = near you or just mentioned; aquel = far from both, or remote in time. In practice ese covers most middle ground and aquel is fading in speech.

False friends for English speakers

Embarazada = pregnant (not embarrassed), actualmente = currently (not actually), asistir = attend, realizar = carry out, éxito = success, librería = bookstore, carpeta = folder, sensible = sensitive.

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Pronunciation 22

B and v: the same sound

Spanish b and v are pronounced identically — hard [b] after pause or n/m (vamos, un beso), soft lips-barely-touching [β] between vowels (la vaca, saber). No English v exists.

C, z, s: seseo — they all sound like s

In all of Latin America, z and soft c (ce, ci) = s: casa, caza identical; cielo = 'sielo'. The Spanish th-sound (distinción) exists only in most of Spain.

The soft d: like 'th' in 'this'

Between vowels and at word ends, d softens to the th of 'this': nada ≈ 'natha', usted, Madrid. Hard d only after pause, n, l: donde, falda.

Diphthongs: one syllable, two vowels

Weak (i, u) + strong (a, e, o) or weak + weak fuse into one syllable: bien, bueno, ciudad, aire. Strong + strong stay separate: le-er, ca-os.

The ñ: año, niño, mañana

Ñ = the 'ny' of 'canyon' said as one sound: año, señor, español. It contrasts with plain n: ano/año are very different words — mind the tilde.

G and j: gato, gente, jugo

G before a/o/u = hard g (gato); before e/i = the j sound (gente). J is always that rough-h (jugo, trabajo) — softer in Latin America than Spain. Gue/gui mute the u: guerra, guitarra; güe/güi sound it: pingüino.

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Regional Spanish 38

Che: the quintessential Argentine address word

Che is the all-purpose vocative — 'hey / mate' — used to hail someone or pepper speech: che, ¿vamos? So iconic that Ernesto Guevara was nicknamed 'el Che' for overusing it.

Everyday Argentine words: laburo, quilombo, pibe, guita

A lunfardo-tinged kit: laburo (work), quilombo (mess), pibe/piba (kid), guita (money), boludo (dude/idiot), copado (cool), bondi (bus), morfar (to eat) — heavily Italian-influenced.

The vanishing present perfect: preterite by default

In Rioplatense, the compound perfect (he hablado) is largely replaced by the simple preterite (hablé) even for recent, relevant past: hoy comí, ¿ya llegó? The perfect survives in the Northwest.

Rioplatense voseo: vos as the full standard

In Argentina and Uruguay, vos is the universal, prestige second person — vos tenés, sos, vení — used in speech, media, and school. Tú is essentially absent; usted marks formality.

Zheísmo & sheísmo: ll and y pronounced 'sh'

The signature Rioplatense sound: ll and y are said as voiced [ʒ] (zheísmo) or, increasingly, voiceless [ʃ] (sheísmo) — calle ≈ 'cashe', yo ≈ 'sho'.

Aymara influence in highland Spanish

Altiplano Spanish (La Paz, El Alto, Oruro) carries Aymara substrate: loanwords (wawa), heavy diminutives, reportive dice/dizque, and topic-fronting.

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