1670 (MDCLXX) was a common year starting on Wednesday of the Gregorian calendar and a common year starting on Saturday of the Julian calendar, the 1670th year of the Common Era (CE) and Anno Domini (AD) designations, the 670th year of the 2nd millennium, the 70th year of the 17th century, and the 1st year of the 1670s decade. As of the start of 1670, the Gregorian calendar was 10 days ahead of the Julian calendar, which remained in localized use until 1923.

Millennium: 2nd millennium
Centuries: 16th century17th century18th century
Decades: 1640s  1650s  1660s  – 1670s –  1680s  1690s  1700s
Years: 1667 1668 166916701671 1672 1673
1670 in other calendars
Gregorian calendar1670
Ab urbe condita2423
Armenian calendar1119
Assyrian calendar6420
Balinese saka calendar1591–1592
Bengali calendar1077
Berber calendar2620
English Regnal year21 Cha. 2 – 22 Cha. 2
Buddhist calendar2214
Burmese calendar1032
Byzantine calendar7178–7179
Chinese calendar己酉(Earth Rooster)
4366 or 4306
    — to —
庚戌年 (Metal Dog)
4367 or 4307
Coptic calendar1386–1387
Discordian calendar2836
Ethiopian calendar1662–1663
Hebrew calendar5430–5431
Hindu calendars
 - Vikram Samvat1726–1727
 - Shaka Samvat1591–1592
 - Kali Yuga4770–4771
Holocene calendar11670
Igbo calendar670–671
Iranian calendar1048–1049
Islamic calendar1080–1081
Japanese calendarKanbun 9
Javanese calendar1592–1593
Julian calendarGregorian minus 10 days
Korean calendar4003
Minguo calendar242 before ROC
Nanakshahi calendar202
Thai solar calendar2212–2213
Tibetan calendar阴土鸡年
(female Earth-Rooster)
1796 or 1415 or 643
    — to —
(male Iron-Dog)
1797 or 1416 or 644