Present — what is happening now, and what happens habitually
| yo | sientoI seat | nosotros | sentamoswe seat |
| tú | sientasyou seat | vosotros | sentáisyou all seat |
| él/ella/Ud. | sientahe/she seats | ellos/Uds. | sientanthey seat |
Present perfect — have —ed; a past still touching now. Spain: today, this week. Latin America: mostly the indefinido instead
| yo | he sentadoI have seated | nosotros | hemos sentadowe have seated |
| tú | has sentadoyou have seated | vosotros | habéis sentadoyou all have seated |
| él/ella/Ud. | ha sentadohe/she has seated | ellos/Uds. | han sentadothey have seated |
Present subjunctive — after que with wishes, doubt, emotion, ojalá
| yo | siente(that) I seat | nosotros | sentemos(that) we seat |
| tú | sientes(that) you seat | vosotros | sentéis(that) you all seat |
| él/ella/Ud. | siente(that) he/she seats | ellos/Uds. | sienten(that) they seat |
Present perfect subjunctive — have —ed, under doubt or emotion: no creo que haya venido
| yo | haya sentado(that) I have seated | nosotros | hayamos sentado(that) we have seated |
| tú | hayas sentado(that) you have seated | vosotros | hayáis sentado(that) you all have seated |
| él/ella/Ud. | haya sentado(that) he/she has seated | ellos/Uds. | hayan sentado(that) they have seated |
Preterite — a finished past action — it started, it ended
| yo | sentéI seated | nosotros | sentamoswe seated |
| tú | sentasteyou seated | vosotros | sentasteisyou all seated |
| él/ella/Ud. | sentóhe/she seated | ellos/Uds. | sentaronthey seated |
Imperfect — used to / was —ing; background, habits, descriptions
| yo | sentabaI used to seat | nosotros | sentábamoswe used to seat |
| tú | sentabasyou used to seat | vosotros | sentabaisyou all used to seat |
| él/ella/Ud. | sentabahe/she used to seat | ellos/Uds. | sentabanthey used to seat |
Past perfect — had —ed; further back than another past event
| yo | había sentadoI had seated | nosotros | habíamos sentadowe had seated |
| tú | habías sentadoyou had seated | vosotros | habíais sentadoyou all had seated |
| él/ella/Ud. | había sentadohe/she had seated | ellos/Uds. | habían sentadothey had seated |
Imperfect subjunctive — si clauses and past-tense wishes: si tuviera, quería que fuera
| yo | sentara(that) I seated | nosotros | sentáramos(that) we seated |
| tú | sentaras(that) you seated | vosotros | sentarais(that) you all seated |
| él/ella/Ud. | sentara(that) he/she seated | ellos/Uds. | sentaran(that) they seated |
Imperfect subjunctive — the same tense, second form; commoner in Spain and in writing
| yo | sentase(that) I seated | nosotros | sentásemos(that) we seated |
| tú | sentases(that) you seated | vosotros | sentaseis(that) you all seated |
| él/ella/Ud. | sentase(that) he/she seated | ellos/Uds. | sentasen(that) they seated |
Past perfect subjunctive — had —ed, hypothetically: si hubiera sabido
| yo | hubiera sentado(that) I had seated | nosotros | hubiéramos sentado(that) we had seated |
| tú | hubieras sentado(that) you had seated | vosotros | hubierais sentado(that) you all had seated |
| él/ella/Ud. | hubiera sentado(that) he/she had seated | ellos/Uds. | hubieran sentado(that) they had seated |
Preterite perfect — had —ed, immediately before; literary, all but extinct
| yo | hube sentadoI had seated | nosotros | hubimos sentadowe had seated |
| tú | hubiste sentadoyou had seated | vosotros | hubisteis sentadoyou all had seated |
| él/ella/Ud. | hubo sentadohe/she had seated | ellos/Uds. | hubieron sentadothey had seated |
Future — will — (spoken Spanish often prefers voy a + infinitivo)
| yo | sentaréI will seat | nosotros | sentaremoswe will seat |
| tú | sentarásyou will seat | vosotros | sentaréisyou all will seat |
| él/ella/Ud. | sentaráhe/she will seat | ellos/Uds. | sentaránthey will seat |
Conditional — would —; also softens a request into politeness
| yo | sentaríaI would seat | nosotros | sentaríamoswe would seat |
| tú | sentaríasyou would seat | vosotros | sentaríaisyou all would seat |
| él/ella/Ud. | sentaríahe/she would seat | ellos/Uds. | sentaríanthey would seat |
Future perfect — will have —ed; done by some future point
| yo | habré sentadoI will have seated | nosotros | habremos sentadowe will have seated |
| tú | habrás sentadoyou will have seated | vosotros | habréis sentadoyou all will have seated |
| él/ella/Ud. | habrá sentadohe/she will have seated | ellos/Uds. | habrán sentadothey will have seated |
Conditional perfect — would have —ed; the road not taken
| yo | habría sentadoI would have seated | nosotros | habríamos sentadowe would have seated |
| tú | habrías sentadoyou would have seated | vosotros | habríais sentadoyou all would have seated |
| él/ella/Ud. | habría sentadohe/she would have seated | ellos/Uds. | habrían sentadothey would have seated |
Future subjunctive — legal and proverbial only: adonde fueres, haz lo que vieres
| yo | sentare(should) I seat | nosotros | sentáremos(should) we seat |
| tú | sentares(should) you seat | vosotros | sentareis(should) you all seat |
| él/ella/Ud. | sentare(should) he/she seat | ellos/Uds. | sentaren(should) they seat |
Imperative (do it) — orders and requests; there is no yo form
| yo | — | nosotros | sentemoslet's seat |
| tú | sientaseat! | vosotros | sentadseat! |
| él/ella/Ud. | sienteseat! | ellos/Uds. | sientenseat! |
Imperative (don't) — no + subjunctive — never the affirmative form with no in front
| yo | — | nosotros | no sentemoslet's not seat |
| tú | no sientesdon't seat | vosotros | no sentéisdon't seat |
| él/ella/Ud. | no sientedon't seat | ellos/Uds. | no sientendon't seat |

Red = the form breaks the regular pattern. Everything in black you could have worked out from the endings alone.
I — the speaker
| Presente | sientoI seat |
| Perfecto | he sentadoI have seated |
| Subj. presente | siente(that) I seat |
| Subj. perfecto | haya sentado(that) I have seated |
| Futuro | sentaréI will seat |
| Condicional | sentaríaI would seat |
| Fut. perfecto | habré sentadoI will have seated |
| Cond. perfecto | habría sentadoI would have seated |
| Subj. futuro | sentare(should) I seat |
| Indefinido | sentéI seated |
| Imperfecto | sentabaI used to seat |
| Pluscuamp. | había sentadoI had seated |
| Subj. imperf. | sentara(that) I seated |
| Subj. -se | sentase(that) I seated |
| Subj. pluscuamp. | hubiera sentado(that) I had seated |
| Pret. anterior | hube sentadoI had seated |
| Imperativo | — |
| Imper. negativo | — |
we — the speaker plus others
| Presente | sentamoswe seat |
| Perfecto | hemos sentadowe have seated |
| Subj. presente | sentemos(that) we seat |
| Subj. perfecto | hayamos sentado(that) we have seated |
| Futuro | sentaremoswe will seat |
| Condicional | sentaríamoswe would seat |
| Fut. perfecto | habremos sentadowe will have seated |
| Cond. perfecto | habríamos sentadowe would have seated |
| Subj. futuro | sentáremos(should) we seat |
| Indefinido | sentamoswe seated |
| Imperfecto | sentábamoswe used to seat |
| Pluscuamp. | habíamos sentadowe had seated |
| Subj. imperf. | sentáramos(that) we seated |
| Subj. -se | sentásemos(that) we seated |
| Subj. pluscuamp. | hubiéramos sentado(that) we had seated |
| Pret. anterior | hubimos sentadowe had seated |
| Imperativo | sentemoslet's seat |
| Imper. negativo | no sentemoslet's not seat |
you (informal) — one person you are familiar with
| Presente | sientasyou seat |
| Perfecto | has sentadoyou have seated |
| Subj. presente | sientes(that) you seat |
| Subj. perfecto | hayas sentado(that) you have seated |
| Futuro | sentarásyou will seat |
| Condicional | sentaríasyou would seat |
| Fut. perfecto | habrás sentadoyou will have seated |
| Cond. perfecto | habrías sentadoyou would have seated |
| Subj. futuro | sentares(should) you seat |
| Indefinido | sentasteyou seated |
| Imperfecto | sentabasyou used to seat |
| Pluscuamp. | habías sentadoyou had seated |
| Subj. imperf. | sentaras(that) you seated |
| Subj. -se | sentases(that) you seated |
| Subj. pluscuamp. | hubieras sentado(that) you had seated |
| Pret. anterior | hubiste sentadoyou had seated |
| Imperativo | sientaseat! |
| Imper. negativo | no sientesdon't seat |
you all — informal plural, Spain only
| Presente | sentáisyou all seat |
| Perfecto | habéis sentadoyou all have seated |
| Subj. presente | sentéis(that) you all seat |
| Subj. perfecto | hayáis sentado(that) you all have seated |
| Futuro | sentaréisyou all will seat |
| Condicional | sentaríaisyou all would seat |
| Fut. perfecto | habréis sentadoyou all will have seated |
| Cond. perfecto | habríais sentadoyou all would have seated |
| Subj. futuro | sentareis(should) you all seat |
| Indefinido | sentasteisyou all seated |
| Imperfecto | sentabaisyou all used to seat |
| Pluscuamp. | habíais sentadoyou all had seated |
| Subj. imperf. | sentarais(that) you all seated |
| Subj. -se | sentaseis(that) you all seated |
| Subj. pluscuamp. | hubierais sentado(that) you all had seated |
| Pret. anterior | hubisteis sentadoyou all had seated |
| Imperativo | sentadseat! |
| Imper. negativo | no sentéisdon't seat |
he, she, you (formal) — one other person — formal you shares it
| Presente | sientahe/she seats |
| Perfecto | ha sentadohe/she has seated |
| Subj. presente | siente(that) he/she seats |
| Subj. perfecto | haya sentado(that) he/she has seated |
| Futuro | sentaráhe/she will seat |
| Condicional | sentaríahe/she would seat |
| Fut. perfecto | habrá sentadohe/she will have seated |
| Cond. perfecto | habría sentadohe/she would have seated |
| Subj. futuro | sentare(should) he/she seat |
| Indefinido | sentóhe/she seated |
| Imperfecto | sentabahe/she used to seat |
| Pluscuamp. | había sentadohe/she had seated |
| Subj. imperf. | sentara(that) he/she seated |
| Subj. -se | sentase(that) he/she seated |
| Subj. pluscuamp. | hubiera sentado(that) he/she had seated |
| Pret. anterior | hubo sentadohe/she had seated |
| Imperativo | sienteseat! |
| Imper. negativo | no sientedon't seat |
they, you all — several others — plural you shares it
| Presente | sientanthey seat |
| Perfecto | han sentadothey have seated |
| Subj. presente | sienten(that) they seat |
| Subj. perfecto | hayan sentado(that) they have seated |
| Futuro | sentaránthey will seat |
| Condicional | sentaríanthey would seat |
| Fut. perfecto | habrán sentadothey will have seated |
| Cond. perfecto | habrían sentadothey would have seated |
| Subj. futuro | sentaren(should) they seat |
| Indefinido | sentaronthey seated |
| Imperfecto | sentabanthey used to seat |
| Pluscuamp. | habían sentadothey had seated |
| Subj. imperf. | sentaran(that) they seated |
| Subj. -se | sentasen(that) they seated |
| Subj. pluscuamp. | hubieran sentado(that) they had seated |
| Pret. anterior | hubieron sentadothey had seated |
| Imperativo | sientenseat! |
| Imper. negativo | no sientendon't seat |

Red = the form breaks the regular pattern. Everything in black you could have worked out from the endings alone.