How do I convert time to epoch time?

Choose the date, clock time, and timezone, then convert that instant to Unix seconds or milliseconds. If the timezone is missing, the result may be off by hours.

Is timestamp to epoch the same as date to epoch?

Usually yes. It means converting a readable timestamp or date-time string into an epoch number.

Should I send epoch seconds or milliseconds to an API?

Follow the API documentation. If it says Unix timestamp, it often means seconds, but JavaScript-oriented APIs may expect milliseconds.

Why does the same date give a different epoch in different timezones?

Because a local wall-clock time only identifies an instant once a timezone is attached. 2026-01-01 00:00 is 1767225600 in UTC but 1767243600 in New York — five hours later in real time. Set the timezone before converting.

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在 JavaScript、Python、SQL、Go 中把日期轉成 Epoch

By unixepochtime.com editorial team2026年5月19日Updated 2026年6月28日

開發者導向的教學,涵蓋如何在 JavaScript、Python、SQL、Go 與 shell 中把日期與時區轉成 Unix epoch。包含 timezone-aware 與 naive 解析、DST gap,以及秒與毫秒的取捨。

為何需要在程式碼裡把日期轉 Epoch

大多數應用以 Unix 整數存放時間戳,但收到的日期是字串 — 表單裡的日曆值、CSV 的日期欄、依特定時區格式化的 webhook 欄位。把這些字串在程式碼裡轉成 epoch,資料庫才能排序、服務才能比較、API 才能接受。本文按 JavaScript、Python、SQL、Go、shell 分別給出地道寫法,以及每個團隊遲早都會踩的時區 bug。

JavaScript:Date、getTime 與帶時區的輸入

JavaScript 內部以毫秒儲存時間。Date.UTC 接受 UTC 牆上時間並返回毫秒 epoch;帶顯式偏移量的 ISO 8601 字串可用 new Date(iso).getTime();除以 1000 取得秒。

Date.UTC(2026, 0, 1, 0, 0, 0) → 1767225600000 (month is zero-indexed)
new Date('2026-01-01T08:00:00-05:00').getTime() → 1767265200000
Math.floor(Date.now() / 1000) → current Unix seconds
Wall-clock in a non-UTC zone needs a zone-aware library (Luxon, date-fns-tz, Temporal)

Python:datetime.timestamp 與 calendar.timegm

Python 的 datetime 物件以 .timestamp() 轉 epoch — 但前提是必須 timezone-aware。naive datetime 會被當作本機本地時間解讀,這是線上 epoch 出錯最常見的原因。

datetime(2026, 1, 1, tzinfo=timezone.utc).timestamp() → 1767225600.0
calendar.timegm(struct_time) → seconds (UTC-only)
datetime.now(ZoneInfo('America/New_York')).timestamp() → zone-aware now
Avoid datetime.fromisoformat(s).timestamp() when s has no offset

SQL:EXTRACT EPOCH、UNIX_TIMESTAMP、UNIX_SECONDS

每個主流資料庫都提供把時間戳欄位轉 epoch 整數的函式。請明確處理欄位時區:TIMESTAMP WITH TIME ZONE 與 TIMESTAMP WITHOUT TIME ZONE 傳入這些函式的行為差別很大。

PostgreSQL: EXTRACT(EPOCH FROM ts) → seconds (double)
MySQL: UNIX_TIMESTAMP(ts) → seconds, naive ts read in session timezone
BigQuery: UNIX_SECONDS(ts) / UNIX_MILLIS(ts) — TIMESTAMP only
SQLite: strftime('%s', ts) → seconds as string, cast to integer

Go 與 shell:time.Unix 與 date +%s

Go 用含偏移量的 layout 解析,再呼叫 .Unix() 取秒、.UnixMilli() 取毫秒。shell 端 GNU date -d 能解析常見日期串,BSD / macOS 的 date -j -f 必須明確指定格式。

Go: t, _ := time.Parse(time.RFC3339, "2026-01-01T00:00:00Z"); t.Unix()
Go: time.Date(2026, 1, 1, 0, 0, 0, 0, time.UTC).Unix()
GNU date: date -d "2026-01-01 00:00:00 UTC" +%s
macOS date: date -j -u -f "%Y-%m-%d %H:%M:%S" "2026-01-01 00:00:00" +%s

FAQ

How do I convert time to epoch time?: Choose the date, clock time, and timezone, then convert that instant to Unix seconds or milliseconds. If the timezone is missing, the result may be off by hours.
Is timestamp to epoch the same as date to epoch?: Usually yes. It means converting a readable timestamp or date-time string into an epoch number.
Should I send epoch seconds or milliseconds to an API?: Follow the API documentation. If it says Unix timestamp, it often means seconds, but JavaScript-oriented APIs may expect milliseconds.
Why does the same date give a different epoch in different timezones?: Because a local wall-clock time only identifies an instant once a timezone is attached. 2026-01-01 00:00 is 1767225600 in UTC but 1767243600 in New York — five hours later in real time. Set the timezone before converting.