Present — what is happening now, and what happens habitually
| yo | reduzcoI reduce | nosotros | reducimoswe reduce |
| tú | reducesyou reduce | vosotros | reducísyou all reduce |
| él/ella/Ud. | reducehe/she reduces | ellos/Uds. | reducenthey reduce |
Present perfect — have —ed; a past still touching now. Spain: today, this week. Latin America: mostly the indefinido instead
| yo | he reducidoI have reduced | nosotros | hemos reducidowe have reduced |
| tú | has reducidoyou have reduced | vosotros | habéis reducidoyou all have reduced |
| él/ella/Ud. | ha reducidohe/she has reduced | ellos/Uds. | han reducidothey have reduced |
Present subjunctive — after que with wishes, doubt, emotion, ojalá
| yo | reduzca(that) I reduce | nosotros | reduzcamos(that) we reduce |
| tú | reduzcas(that) you reduce | vosotros | reduzcáis(that) you all reduce |
| él/ella/Ud. | reduzca(that) he/she reduces | ellos/Uds. | reduzcan(that) they reduce |
Present perfect subjunctive — have —ed, under doubt or emotion: no creo que haya venido
| yo | haya reducido(that) I have reduced | nosotros | hayamos reducido(that) we have reduced |
| tú | hayas reducido(that) you have reduced | vosotros | hayáis reducido(that) you all have reduced |
| él/ella/Ud. | haya reducido(that) he/she has reduced | ellos/Uds. | hayan reducido(that) they have reduced |
Preterite — a finished past action — it started, it ended
| yo | redujeI reduced | nosotros | redujimoswe reduced |
| tú | redujisteyou reduced | vosotros | redujisteisyou all reduced |
| él/ella/Ud. | redujohe/she reduced | ellos/Uds. | redujeronthey reduced |
Imperfect — used to / was —ing; background, habits, descriptions
| yo | reducíaI used to reduce | nosotros | reducíamoswe used to reduce |
| tú | reducíasyou used to reduce | vosotros | reducíaisyou all used to reduce |
| él/ella/Ud. | reducíahe/she used to reduce | ellos/Uds. | reducíanthey used to reduce |
Past perfect — had —ed; further back than another past event
| yo | había reducidoI had reduced | nosotros | habíamos reducidowe had reduced |
| tú | habías reducidoyou had reduced | vosotros | habíais reducidoyou all had reduced |
| él/ella/Ud. | había reducidohe/she had reduced | ellos/Uds. | habían reducidothey had reduced |
Imperfect subjunctive — si clauses and past-tense wishes: si tuviera, quería que fuera
| yo | redujera(that) I reduced | nosotros | redujéramos(that) we reduced |
| tú | redujeras(that) you reduced | vosotros | redujerais(that) you all reduced |
| él/ella/Ud. | redujera(that) he/she reduced | ellos/Uds. | redujeran(that) they reduced |
Imperfect subjunctive — the same tense, second form; commoner in Spain and in writing
| yo | redujese(that) I reduced | nosotros | redujésemos(that) we reduced |
| tú | redujeses(that) you reduced | vosotros | redujeseis(that) you all reduced |
| él/ella/Ud. | redujese(that) he/she reduced | ellos/Uds. | redujesen(that) they reduced |
Past perfect subjunctive — had —ed, hypothetically: si hubiera sabido
| yo | hubiera reducido(that) I had reduced | nosotros | hubiéramos reducido(that) we had reduced |
| tú | hubieras reducido(that) you had reduced | vosotros | hubierais reducido(that) you all had reduced |
| él/ella/Ud. | hubiera reducido(that) he/she had reduced | ellos/Uds. | hubieran reducido(that) they had reduced |
Preterite perfect — had —ed, immediately before; literary, all but extinct
| yo | hube reducidoI had reduced | nosotros | hubimos reducidowe had reduced |
| tú | hubiste reducidoyou had reduced | vosotros | hubisteis reducidoyou all had reduced |
| él/ella/Ud. | hubo reducidohe/she had reduced | ellos/Uds. | hubieron reducidothey had reduced |
Future — will — (spoken Spanish often prefers voy a + infinitivo)
| yo | reduciréI will reduce | nosotros | reduciremoswe will reduce |
| tú | reducirásyou will reduce | vosotros | reduciréisyou all will reduce |
| él/ella/Ud. | reduciráhe/she will reduce | ellos/Uds. | reduciránthey will reduce |
Conditional — would —; also softens a request into politeness
| yo | reduciríaI would reduce | nosotros | reduciríamoswe would reduce |
| tú | reduciríasyou would reduce | vosotros | reduciríaisyou all would reduce |
| él/ella/Ud. | reduciríahe/she would reduce | ellos/Uds. | reduciríanthey would reduce |
Future perfect — will have —ed; done by some future point
| yo | habré reducidoI will have reduced | nosotros | habremos reducidowe will have reduced |
| tú | habrás reducidoyou will have reduced | vosotros | habréis reducidoyou all will have reduced |
| él/ella/Ud. | habrá reducidohe/she will have reduced | ellos/Uds. | habrán reducidothey will have reduced |
Conditional perfect — would have —ed; the road not taken
| yo | habría reducidoI would have reduced | nosotros | habríamos reducidowe would have reduced |
| tú | habrías reducidoyou would have reduced | vosotros | habríais reducidoyou all would have reduced |
| él/ella/Ud. | habría reducidohe/she would have reduced | ellos/Uds. | habrían reducidothey would have reduced |
Future subjunctive — legal and proverbial only: adonde fueres, haz lo que vieres
| yo | redujere(should) I reduce | nosotros | redujéremos(should) we reduce |
| tú | redujeres(should) you reduce | vosotros | redujereis(should) you all reduce |
| él/ella/Ud. | redujere(should) he/she reduce | ellos/Uds. | redujeren(should) they reduce |
Imperative (do it) — orders and requests; there is no yo form
| yo | — | nosotros | reduzcamoslet's reduce |
| tú | reducereduce! | vosotros | reducidreduce! |
| él/ella/Ud. | reduzcareduce! | ellos/Uds. | reduzcanreduce! |
Imperative (don't) — no + subjunctive — never the affirmative form with no in front
| yo | — | nosotros | no reduzcamoslet's not reduce |
| tú | no reduzcasdon't reduce | vosotros | no reduzcáisdon't reduce |
| él/ella/Ud. | no reduzcadon't reduce | ellos/Uds. | no reduzcandon't reduce |

Red = the form breaks the regular pattern. Everything in black you could have worked out from the endings alone.
I — the speaker
| Presente | reduzcoI reduce |
| Perfecto | he reducidoI have reduced |
| Subj. presente | reduzca(that) I reduce |
| Subj. perfecto | haya reducido(that) I have reduced |
| Futuro | reduciréI will reduce |
| Condicional | reduciríaI would reduce |
| Fut. perfecto | habré reducidoI will have reduced |
| Cond. perfecto | habría reducidoI would have reduced |
| Subj. futuro | redujere(should) I reduce |
| Indefinido | redujeI reduced |
| Imperfecto | reducíaI used to reduce |
| Pluscuamp. | había reducidoI had reduced |
| Subj. imperf. | redujera(that) I reduced |
| Subj. -se | redujese(that) I reduced |
| Subj. pluscuamp. | hubiera reducido(that) I had reduced |
| Pret. anterior | hube reducidoI had reduced |
| Imperativo | — |
| Imper. negativo | — |
we — the speaker plus others
| Presente | reducimoswe reduce |
| Perfecto | hemos reducidowe have reduced |
| Subj. presente | reduzcamos(that) we reduce |
| Subj. perfecto | hayamos reducido(that) we have reduced |
| Futuro | reduciremoswe will reduce |
| Condicional | reduciríamoswe would reduce |
| Fut. perfecto | habremos reducidowe will have reduced |
| Cond. perfecto | habríamos reducidowe would have reduced |
| Subj. futuro | redujéremos(should) we reduce |
| Indefinido | redujimoswe reduced |
| Imperfecto | reducíamoswe used to reduce |
| Pluscuamp. | habíamos reducidowe had reduced |
| Subj. imperf. | redujéramos(that) we reduced |
| Subj. -se | redujésemos(that) we reduced |
| Subj. pluscuamp. | hubiéramos reducido(that) we had reduced |
| Pret. anterior | hubimos reducidowe had reduced |
| Imperativo | reduzcamoslet's reduce |
| Imper. negativo | no reduzcamoslet's not reduce |
you (informal) — one person you are familiar with
| Presente | reducesyou reduce |
| Perfecto | has reducidoyou have reduced |
| Subj. presente | reduzcas(that) you reduce |
| Subj. perfecto | hayas reducido(that) you have reduced |
| Futuro | reducirásyou will reduce |
| Condicional | reduciríasyou would reduce |
| Fut. perfecto | habrás reducidoyou will have reduced |
| Cond. perfecto | habrías reducidoyou would have reduced |
| Subj. futuro | redujeres(should) you reduce |
| Indefinido | redujisteyou reduced |
| Imperfecto | reducíasyou used to reduce |
| Pluscuamp. | habías reducidoyou had reduced |
| Subj. imperf. | redujeras(that) you reduced |
| Subj. -se | redujeses(that) you reduced |
| Subj. pluscuamp. | hubieras reducido(that) you had reduced |
| Pret. anterior | hubiste reducidoyou had reduced |
| Imperativo | reducereduce! |
| Imper. negativo | no reduzcasdon't reduce |
you all — informal plural, Spain only
| Presente | reducísyou all reduce |
| Perfecto | habéis reducidoyou all have reduced |
| Subj. presente | reduzcáis(that) you all reduce |
| Subj. perfecto | hayáis reducido(that) you all have reduced |
| Futuro | reduciréisyou all will reduce |
| Condicional | reduciríaisyou all would reduce |
| Fut. perfecto | habréis reducidoyou all will have reduced |
| Cond. perfecto | habríais reducidoyou all would have reduced |
| Subj. futuro | redujereis(should) you all reduce |
| Indefinido | redujisteisyou all reduced |
| Imperfecto | reducíaisyou all used to reduce |
| Pluscuamp. | habíais reducidoyou all had reduced |
| Subj. imperf. | redujerais(that) you all reduced |
| Subj. -se | redujeseis(that) you all reduced |
| Subj. pluscuamp. | hubierais reducido(that) you all had reduced |
| Pret. anterior | hubisteis reducidoyou all had reduced |
| Imperativo | reducidreduce! |
| Imper. negativo | no reduzcáisdon't reduce |
he, she, you (formal) — one other person — formal you shares it
| Presente | reducehe/she reduces |
| Perfecto | ha reducidohe/she has reduced |
| Subj. presente | reduzca(that) he/she reduces |
| Subj. perfecto | haya reducido(that) he/she has reduced |
| Futuro | reduciráhe/she will reduce |
| Condicional | reduciríahe/she would reduce |
| Fut. perfecto | habrá reducidohe/she will have reduced |
| Cond. perfecto | habría reducidohe/she would have reduced |
| Subj. futuro | redujere(should) he/she reduce |
| Indefinido | redujohe/she reduced |
| Imperfecto | reducíahe/she used to reduce |
| Pluscuamp. | había reducidohe/she had reduced |
| Subj. imperf. | redujera(that) he/she reduced |
| Subj. -se | redujese(that) he/she reduced |
| Subj. pluscuamp. | hubiera reducido(that) he/she had reduced |
| Pret. anterior | hubo reducidohe/she had reduced |
| Imperativo | reduzcareduce! |
| Imper. negativo | no reduzcadon't reduce |
they, you all — several others — plural you shares it
| Presente | reducenthey reduce |
| Perfecto | han reducidothey have reduced |
| Subj. presente | reduzcan(that) they reduce |
| Subj. perfecto | hayan reducido(that) they have reduced |
| Futuro | reduciránthey will reduce |
| Condicional | reduciríanthey would reduce |
| Fut. perfecto | habrán reducidothey will have reduced |
| Cond. perfecto | habrían reducidothey would have reduced |
| Subj. futuro | redujeren(should) they reduce |
| Indefinido | redujeronthey reduced |
| Imperfecto | reducíanthey used to reduce |
| Pluscuamp. | habían reducidothey had reduced |
| Subj. imperf. | redujeran(that) they reduced |
| Subj. -se | redujesen(that) they reduced |
| Subj. pluscuamp. | hubieran reducido(that) they had reduced |
| Pret. anterior | hubieron reducidothey had reduced |
| Imperativo | reduzcanreduce! |
| Imper. negativo | no reduzcandon't reduce |

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