How to parse unix timestamp to time.Time

I'm trying to parse an Unix timestamp but I get out of range error. That doesn't really makes sense to me, because the layout is correct (as in the Go docs):

package main

import "fmt"
import "time"

func main() {
    tm, err := time.Parse("1136239445", "1405544146")
    if err != nil{
        panic(err)
    }

    fmt.Println(tm)
}

Playground

The time.Parse function does not do Unix timestamps. Instead you can use strconv.ParseInt to parse the string to int64 and create the timestamp with time.Unix:

package main

import (
	"fmt"
	"time"
	"strconv"
)

func main() {
	i, err := strconv.ParseInt("1405544146", 10, 64)
	if err != nil {
		panic(err)
	}
	tm := time.Unix(i, 0)
	fmt.Println(tm)
}

Output:

2014-07-16 20:55:46 +0000 UTC

Playground: http://play.golang.org/p/v_j6UIro7a

Edit:

Changed from strconv.Atoi to strconv.ParseInt to avoid int overflows on 32 bit systems.

You can directly use time.Unix function of time which converts the unix time stamp to UTC

package main

import (
  "fmt"
  "time"
)


func main() {
	unixTimeUTC:=time.Unix(1405544146, 0) //gives unix time stamp in utc 

    unitTimeInRFC3339 :=unixTimeUTC.Format(time.RFC3339) // converts utc time to RFC3339 format

	fmt.Println("unix time stamp in UTC :--->",unixTimeUTC)
    fmt.Println("unix time stamp in unitTimeInRFC3339 format :->",unitTimeInRFC3339)
}

Output

unix time stamp in UTC :---> 2014-07-16 20:55:46 +0000 UTC
unix time stamp in unitTimeInRFC3339 format :----> 2014-07-16T20:55:46Z

Check in Go Playground: https://play.golang.org/p/5FtRdnkxAd

Sharing a few functions which I created for dates:

Please note that I wanted to get time for a particular location (not just UTC time). If you want UTC time, just remove loc variable and .In(loc) function call.

func GetTimeStamp() string {
     loc, _ := time.LoadLocation("America/Los_Angeles")
     t := time.Now().In(loc)
     return t.Format("20060102150405")
}
func GetTodaysDate() string {
    loc, _ := time.LoadLocation("America/Los_Angeles")
    current_time := time.Now().In(loc)
    return current_time.Format("2006-01-02")
}

func GetTodaysDateTime() string {
    loc, _ := time.LoadLocation("America/Los_Angeles")
    current_time := time.Now().In(loc)
    return current_time.Format("2006-01-02 15:04:05")
}

func GetTodaysDateTimeFormatted() string {
    loc, _ := time.LoadLocation("America/Los_Angeles")
    current_time := time.Now().In(loc)
    return current_time.Format("Jan 2, 2006 at 3:04 PM")
}

func GetTimeStampFromDate(dtformat string) string {
    form := "Jan 2, 2006 at 3:04 PM"
    t2, _ := time.Parse(form, dtformat)
    return t2.Format("20060102150405")
}

for millis unix timestamp precision, in go1.18

    i, err := strconv.ParseInt("1652084489543", 10, 64)
    if err != nil {
        panic(err)
    }
    tm := time.UnixMilli(i)
    fmt.Println(tm)

This is an old question but I noticed that a practical answer is missing.

For example, we were working with the MavLink protocol and we need to process a message with a structure defined here.

If we have this data structure:

So, we receive constant updates that we need to process using the time_boot_ms as reference to insert them on the database and synchronize them with other messages.

What can we do?

As we noticed, the time is in milliseconds and everyone, that has some experience with Go, knows that for some unknown reason it's just way too complex to convert a millisecond resolution Unix timestamp to time.Time. The built-in time.Unix() function only supports second and nanosecond precision.

How we can get millisecond precision?

Well, we might wait until they release the version 1.7 of Go or we either have to multiply the milliseconds to nanoseconds or split them into seconds and nanoseconds.

Lets implement the second idea, spit the into seconds and nanoseconds:

unixUTCtime := time.Unix(ms/int64(1000), (ms%int64(1000))*int64(1000000))

Now we can encapsulate it in a func and use it in our main like this:

package main

import (
    "fmt"
    "time"
)

const msInSecond int64 = 1e3
const nsInMillisecond int64 = 1e6

// UnixToMS Converts Unix Epoch from milliseconds to time.Time
func UnixToMS (ms int64) time.Time {
    return time.Unix(ms/msInSecond, (ms%msInSecond)*nsInMillisecond)
}


func main() {
	unixTimes := [...]int64{758991688, 758992188, 758992690, 758993186}
	var unixUTCTimes []time.Time
	for index, unixTime := range unixTimes {
		unixUTCTimes = append(unixUTCTimes, UnixToMS(unixTime))
		if index > 0 {
			timeDifference := unixUTCTimes[index].Sub(unixUTCTimes[index-1])
			fmt.Println("Time difference in ms :--->", timeDifference)
		}
	}
}

The output will be:

Time difference in ms :---> 500ms
Time difference in ms :---> 502ms
Time difference in ms :---> 496ms

Check in Go Playground

Update

From version 1.7, go now provides millisecond resolution either to convert a unix time represented as a int64 number into a Time type (nanosecond precision) using time.UnixMilli function or from Time into millisecond precision using UnixMilli function. This is their implementation:

func Unix(sec int64, nsec int64) Time {
	if nsec < 0 || nsec >= 1e9 {
		n := nsec / 1e9
		sec += n
		nsec -= n * 1e9
		if nsec < 0 {
			nsec += 1e9
			sec--
		}
	}
	return unixTime(sec, int32(nsec))
}


func UnixMilli(msec int64) Time {
	return Unix(msec/1e3, (msec%1e3)*1e6)
}

func (t Time) UnixMilli() int64 {
	return t.unixSec()*1e3 + int64(t.nsec())/1e6
}

How to use this Teo?

Very simple just modify this line from the previous implementation of our example:

unixUTCTimes = append(unixUTCTimes, UnixToMS(unixTime))

with this code:

unixUTCTimes = append(unixUTCTimes, time.UnixMilli(unixTime))

No need of other functions just call time.UnixMilli(unixTime). Check the playground here.

I do a lot of logging where the timestamps are float64 and use this function to get the timestamps as string:

func dateFormat(layout string, d float64) string{
	intTime := int64(d)
	t := time.Unix(intTime, 0)
	if layout == "" {
		layout = "2006-01-02 15:04:05"
	}
	return t.Format(layout)
}

According to the go documentation, Unix returns a local time.

> Unix returns the local Time corresponding to the given Unix time

This means the output would depend on the machine your code runs on, which, most often is what you need, but sometimes, you may want to have the value in UTC.

To do so, I adapted the snippet to make it return a time in UTC:

i, err := strconv.ParseInt("1405544146", 10, 64)
if err != nil {
	panic(err)
}
tm := time.Unix(i, 0)
fmt.Println(tm.UTC())

This prints on my machine (in CEST)

2014-07-16 20:55:46 +0000 UTC