Using an offset to calculate Timezone is a wrong approach, and you will always encounter problems. Time zones and daylight saving rules may change on several occasions during a year, and It's difficult to keep up with changes.

To get the system's IANA timezone in JavaScript, you should use

console.log(Intl.DateTimeFormat().resolvedOptions().timeZone)

As of April 2023, this works in 95.42% of the browsers used globally.

Old compatibility information

ecma-402/1.0 says that timeZone may be undefined if not provided to constructor. However, future draft (3.0) fixed that issue by changing to system default timezone.

In this version of the ECMAScript Internationalization API, the timeZone property will remain undefined if no timeZone property was provided in the options object provided to the Intl.DateTimeFormat constructor. However, applications should not rely on this, as future versions may return a String value identifying the host environment’s current time zone instead.

in ecma-402/3.0 which is still in a draft it changed to

In this version of the ECMAScript 2015 Internationalization API, the timeZone property will be the name of the default time zone if no timeZone property was provided in the options object provided to the Intl.DateTimeFormat constructor. The previous version left the timeZone property undefined in this case.

Edit 3-19-2022 - WARNING: I no longer recommend this approach as it has issues with multiple browsers and locales.

I realize this answer is a bit off topic but I imagine many of us looking for an answer also wanted to format the time zone for display and perhaps get the zone abbreviation too. So here it goes...

If you want the client timezone nicely formatted you can rely on the JavaScript Date.toString method and do:

var split = new Date().toString().split(" ");
var timeZoneFormatted = split[split.length - 2] + " " + split[split.length - 1];

This will give you "GMT-0400 (EST)" for example, including the timezone minutes when applicable.

Alternatively, with regex you can extract any desired part:

For "GMT-0400 (EDT)" :

console.log(new Date().toString().match(/([A-Z]+[\+-][0-9]+.*)/)[1])

For "GMT-0400" :

    console.log(new Date().toString().match(/([A-Z]+[\+-][0-9]+)/)[1])

For just "EDT" :

console.log(new Date().toString().match(/\(([A-Za-z\s].*)\)/)[1])

For just "-0400":

console.log(new Date().toString().match(/([-\+][0-9]+)\s/)[1])

Date.toString reference: https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Date/toString

EDIT 10/6/2020 - The above solution may not work in all browsers and locales. If possible in your scenario, I would recommend utilizing a javascript library like date-fns, luxon or dayjs which provide timezone support.

I wrote a function in my project, which returns the timezone in hh:mm format. I hope this may help someone:

function getTimeZone() {
    var offset = new Date().getTimezoneOffset(), o = Math.abs(offset);
    return (offset < 0 ? "+" : "-") + ("00" + Math.floor(o / 60)).slice(-2) + ":" + ("00" + (o % 60)).slice(-2);
}

// Outputs: +5:00

function getTimeZone() {
  var offset = new Date().getTimezoneOffset(), o = Math.abs(offset);
  return (offset < 0 ? "+" : "-") + ("00" + Math.floor(o / 60)).slice(-2) + ":" + ("00" + (o % 60)).slice(-2);
}


// See output
document.write(getTimeZone());

Working Fiddle

Code with comments

/**
 * Get client side timezone.
 *
 * @returns {(+|-)HH:mm} - Where `HH` is 2 digits hours and `mm` 2 digits minutes.
 * @example
 * // From Indian/Reunion with UTC+4
 * // '+04:00'
 * getTimeZone()
 */
const getTimeZone = () => {
  const timezoneOffset = new Date().getTimezoneOffset()
  const offset = Math.abs(timezoneOffset)
  const offsetOperator = timezoneOffset < 0 ? '+' : '-'
  const offsetHours = Math.floor(offset / 60).toString().padStart(2, '0')
  const offsetMinutes = Math.floor(offset % 60).toString().padStart(2, '0')

  return `${offsetOperator}${offsetHours}:${offsetMinutes}`
}

It's already been answered how to get offset in minutes as an integer, but in case anyone wants the local GMT offset as a string e.g. "+1130":

function pad(number, length){
    var str = "" + number
    while (str.length < length) {
        str = '0'+str
    }
    return str
}

var offset = new Date().getTimezoneOffset()
offset = ((offset<0? '+':'-')+ // Note the reversed sign!
          pad(parseInt(Math.abs(offset/60)), 2)+
          pad(Math.abs(offset%60), 2))

You can use:

moment-timezone

<script src="moment.js"></script>
<script src="moment-timezone-with-data.js"></script>

// retrieve timezone by name (i.e. "America/Chicago")
moment.tz.guess();

Browser time zone detection is rather tricky to get right, as there is little information provided by the browser.

Moment Timezone uses Date.getTimezoneOffset() and Date.toString() on a handful of moments around the current year to gather as much information about the browser environment as possible. It then compares that information with all the time zone data loaded and returns the closest match. In case of ties, the time zone with the city with largest population is returned.

console.log(moment.tz.guess()); // America/Chicago

A one-liner that gives both the offset and the time zone is to simply call toTimeString() on a new Date object. From MDN:

The toTimeString() method returns the time portion of a Date object in human readable form in American English.

The catch is that the timezone is not in the standard IANA format; it's somewhat more user-friendly, than the "continent/city" IANA format. Try it out:

console.log(new Date().toTimeString().slice(9));
console.log(Intl.DateTimeFormat().resolvedOptions().timeZone);
console.log(new Date().getTimezoneOffset() / -60);

In California right now, toTimeString() returns Pacific Daylight Time while the Intl API returns America/Los_Angeles. In Colombia, you'd get Colombia Standard Time, vs. America/Bogota.

Note that many other answers to this question attempt to obtain the same information by calling Date.toString(). That approach is not that reliable, as MDN explains:

Date instances refer to a specific point in time. Calling toString() will return the date formatted in a human readable form in American English. [...] Sometimes it is desirable to obtain a string of the time portion; such a thing can be accomplished with the toTimeString() method.

The toTimeString() method is especially useful because compliant engines implementing ECMA-262 may differ in the string obtained from toString() for Date objects, as the format is implementation-dependent; simple string slicing approaches may not produce consistent results across multiple engines.

This question already has 30+ answers, but I am sure there are people who will come here and really don't know what they are looking for.

Surprise! you are about to open a can of worms!

I strongly recommend reading this article that I wrote recently about the headaches of dealing with TimeZones in JS! https://medium.com/@EyeDin/time-and-time-zone-headaches-in-javascript-ae4d873a665d

What are you EXACTLY looking for?

Depending on your actually use case, you actually need different things.

1) A way to convert a fixed point-in-time (like November 13th of 2021 at 11:35:21pm in San Francisco) to the user's wall-clock time, who might be anywhere in the world.

Use .toLocaleString().

It has more customization parameters for formatting than you can think of, via its two parameters of locale and options listed at DateTimeFormat. It even supports different calendars, languages, ways of formatting year, month, day, etc. (no passed parameter will use the user's default settings, which might be the ideal.)

As a developer, just pass that point-in-time value (e.g. opening time of a Sales event, or a competition) as UNIX timestamp number (that's the number of seconds from 1/1/1970 in UTC, timezone-agnostic and DST0agnostic) to the client, and then do new Date(timestamp).toLocaleString(). e.g. for that point-of-time above, the value is 1636875321000 (in milliseconds), via +dateWithTimeZone("America/Los_Angeles",2021,10,13,23,35,21) using the function from this answer.

2) Be able to send the user a notification/email at 9am of their local time, 3 months from now

This is a totally different requirement! Like, very very different!

Isn't GMT-8:00 enough?

No!

That's just the time zone the user is at, at one point of time, like "right now, today".

• How would you know if the user has Daylight Saving or not? (Arizona in the US doesn't, and so many other countries and states, and even counties!)
• How would you know if the user is in the DST or out of it? Is it winter in San Francisco (GMT-8) or summer in Alaska (again, GMT-8). See this giant list to freak out: https://en.wikipedia.org/wiki/List_of_tz_database_time_zones

Isn't "PDT" enough for that?

No!

First of all, PDT isn't even a year-round thing. It's November now and timeanddate.com says "No locations currently on PDT. Would you like to see PST?" (read my Medium article above for more details.)

Unless you are going for the cosmetic from-client-to-client UI string, this PDT/CEST/etc. doesn't worth anything!

Why? Because Tijuana in Mexico and San Francisco in the US are both in PDT during June, but they have different DST (Daylight Saving) days that they switch to PST. And you need to know that!

US's DST days in 2022 are Mar 13, 2022 to Nov 6, 2022. Mexico's DST days in 2022 are April 3, 2022 to Oct 30, 2022. So, while Tijuana and San Francisco are sharing that "PDT/PST" thing in almost 93% of the days, in 7% of the days (e.g. Mar 14 till April 3, and Oct 31 till Nov 6 in 2022) they don't match.

So, even if you know it's November and you know the user is in PDT, you cannot tell when (which timestamp number) would be 9am of April 1st of 2022 in the user's device.

PS. Worse if you are trying to get that PDT from new Date().toString(). FYI, if you change the locale of your machine to es-MX (Spanish, that's the language of 13% of the US population), this is what you get:

> new Date().toString()
'Sun Nov 14 2021 00:47:25 GMT-0800 (hora estándar del Pacífico)'

Good Luck with hedP!

Then, what should I do?

The ONLY CORRECT WAY is to use IANA (read "standard") Time Zone values. That's the second column of this Wikipedia page. It comes from:

const timeZoneIANA = Intl.DateTimeFormat().resolvedOptions().timeZone;

It returns the IANA value, which is America/Los_Angeles for San Francisco. This is the value you should store in your DB for the user, if anything. You can get all sorts of information about it at from timezones.json package, and convert a time from/to that timezone, plus the day (which matters) like this answer.

What about IE11?

IE11 doesn't support that Intl.... thing. Most polyfills are just guessing it and are inaccurate. So, try to drop support for IE11, or use a library and prepare yourself for some inaccuracy.

3) I just want to find out their time zone offset at the moment (e.g. -8:00)

You probably shouldn't. I cannot think of any real reason that you need this. Again, knowing this value for today, doesn't tell you what would this value be even tomorrow.

Anyhow, you can always get that value by

new Date().getTimezoneOffset() / 60

in client side.

NOTE: .getTimezoneOffset() is NOT the timezone offset of the date object, you are calling it on. Please read the documentation.

To be accurate, it takes the passed Date object (which has a timestamp, which refer to a single point-of-time in the history), and then tells what's the difference between the UTC time and local time at the point-of-time.

Again, it depends on the date. See:

console.log(new Date("6/13/2021").getTimezoneOffset() / 60); // It's 7 on a machine that runs in San Francisco
console.log(new Date("11/13/2021").getTimezoneOffset() / 60); // It's 8 on a machine that runs in in San Francisco

Any libraries?

Here is a list of libraries that support time zone exchanges.

But, remember, you have to solve the design problem first, and then look for the code. Things around time zone can easily get complicated and you have to know "PDT" and "GMT-8" are NOT year-round informative/valuable time zone values to store in the DB for the user. :)

try getTimezoneOffset() of the Date object:

var curdate = new Date()
var offset = curdate.getTimezoneOffset()

This method returns time zone offset in minutes which is the difference between GMT and local time in minutes.

JavaScript:

var d = new Date();
var n = d.getTimezoneOffset();
var timezone = n / -60;
console.log(timezone);

as mentioned by others, to get a timezone :

const tz = Intl.DateTimeFormat().resolvedOptions().timeZone

Not mentioned before, to get the offset from the timezone, use locale "ia" (see https://stackoverflow.com/a/64262840/1061871)

const tz = Intl.DateTimeFormat().resolvedOptions().timeZone

const getOffset = (tz) => Intl.DateTimeFormat("ia", {
                       timeZoneName: "shortOffset",
                       timeZone : tz
                     })
                    .formatToParts()
                    .find((i) => i.type === "timeZoneName").value // => "GMT+/-hh:mm"
                    .slice(3); //=> +/-hh:mm

console.log(tz + ' UTC' + getOffset(tz))

Try this :

new Date().toLocaleString("en-US",Intl.DateTimeFormat().resolvedOptions().timeZone)

This will look for timeZone on your client's browser.

With moment.js:

moment().format('zz');

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Intl/DateTimeFormat/DateTimeFormat

The Intl.DateTimeFormat() constructor creates Intl.DateTimeFormat objects that enable language-sensitive date and time formatting.

Intl.DateTimeFormat().resolvedOptions().timeZone // Asia/Kolkata

Timezone in hours-

var offset = new Date().getTimezoneOffset();
if(offset<0)
    console.log( "Your timezone is- GMT+" + (offset/-60));
else
    console.log( "Your timezone is- GMT-" + offset/60);

If you want to be precise as you mentioned in comment, then you should try like this-

var offset = new Date().getTimezoneOffset();

if(offset<0)
{
    var extraZero = "";
    if(-offset%60<10)
      extraZero="0";

    console.log( "Your timezone is- GMT+" + Math.ceil(offset/-60)+":"+extraZero+(-offset%60));
}
else
{
    var extraZero = "";
    if(offset%60<10)
      extraZero="0";

    console.log( "Your timezone is- GMT-" + Math.floor(offset/60)+":"+extraZero+(offset%60));
}

With momentjs, you can find current timezone as

console.log(moment().utcOffset()); // (-240, -120, -60, 0, 60, 120, 240, etc.)

<script src="https://cdn.jsdelivr.net/momentjs/2.13.0/moment.min.js"></script>

With dayjs, you can find current timezone as

console.log(dayjs().utcOffset()); // (-240, -120, -60, 0, 60, 120, 240, etc.)

<script src="https://unpkg.com/[email protected]/dayjs.min.js"></script>

Both API returns utc offset in minutes.

• moment Doc
• Dayjs Doc

This might not be the most elegant solution but it is the most versatile.

This uses the timeZoneName property of Intl.DateTimeFormat

function getTimeZone(zoneName = "long") {
    // set up formatter
    let formatter = new Intl.DateTimeFormat(undefined, {
        timeZoneName: zoneName
    });
    // run formatter on current date
    return formatter.formatToParts(Date.now())
        // extract the actual value from the formatter, only reliable way i can find to do this
        .find(formatted => formatted.type === "timeZoneName")['value'];
}
// console.log every type
for (const zoneName of ['short', 'long', 'shortOffset', 'longOffset', 'shortGeneric', 'longGeneric']) {
    console.log(`${zoneName}: ${getTimeZone(zoneName)}`)
}
/*
short: CDT
long: Central Daylight Time
shortOffset: GMT-5
longOffset: GMT-05:00
shortGeneric: CT
longGeneric: Central Time
*/

This not only gets the formatted GMT offset time (i.e. GMT-5), but also the colloquial name of the timezone (i.e. Central Daylight Time)

The only thing this method doesn't do is get the IANA timezone. I recommend the top answer for that.

As far as I'm aware, DateTimeFormat doesn't have a way to do custom formatting, hence the use of formatToParts, which seems to be the only reliable way to get just the timezone.

something important to note that only short and long are officially defined in the current ECMAscript specs, the other 4 options are part of a proposal that is only somewhat standard, notably missing on safari as of writing this, though it is in progress

This value is from user's machine and it can be changed anytime so I think it doesn't matter, I just want to get an approximate value and then convert it to GMT in my server.

For example, I am from Taiwan and it returns "+8" for me.

Working example

JS

function timezone() {
    var offset = new Date().getTimezoneOffset();
    var minutes = Math.abs(offset);
    var hours = Math.floor(minutes / 60);
    var prefix = offset < 0 ? "+" : "-";
    return prefix+hours;
}


$('#result').html(timezone());

HTML

<div id="result"></div>

Result

+8

See this resultant operator was opposite to the Timezone .So apply some math function then validate the num less or more.

See the MDN document

var a = new Date().getTimezoneOffset();

var res = -Math.round(a/60)+':'+-(a%60);
res = res < 0 ?res : '+'+res;

console.log(res)

As an alternative to new Date().getTimezoneOffset() and moment().format('zz'), you can also use momentjs:

var offset = moment.parseZone(Date.now()).utcOffset() / 60
console.log(offset);

<script src="https://cdn.jsdelivr.net/momentjs/2.13.0/moment.min.js"></script>

jstimezone is also quite buggy and unmaintained (https://bitbucket.org/pellepim/jstimezonedetect/issues?status=new&status=open)

function getLocalTimeZone() {
    var dd = new Date();
    var ddStr = dd.toString();
    var ddArr = ddStr.split(' ');
    var tmznSTr = ddArr[5];
    tmznSTr = tmznSTr.substring(3, tmznSTr.length);
    return tmznSTr;
}

Example : Thu Jun 21 2018 18:12:50 GMT+0530 (India Standard Time)

O/P : +0530

Try this,

new Date().toString().split("GMT")[1].split(" (")[0]

If all you need is the "MST" or the "EST" time zone abbreviation:

function getTimeZone(){
    var now = new Date().toString();
    var timeZone = now.replace(/.*[(](.*)[)].*/,'$1');//extracts the content between parenthesis
    return timeZone;
}
console.log(getTimeZone());

16 years later and we have Temporal starting to appear in browsers, making date matters much simpler. In this case both timezone and offset can be obtained easily thus:

if ('Temporal' in window) {  
  console.log(Temporal.Now.timeZoneId())
  console.log(Temporal.Now.zonedDateTimeISO().offset)
}

Right now only the latest version of Firefox has it implemented.

Reference: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Temporal/Now

On the new Date() you can get the offset, to get the timezone name you may do:

new Date().toString().replace(/(.*\((.*)\).*)/, '$2');

you get the value between () in the end of the date, that is the name of the timezone.

This would be my solution:

// For time zone:
const timeZone = /\((.*)\)/.exec(new Date().toString())[1];

// Offset hours:
const offsetHours = new Date().getTimezoneOffset() / 60;

console.log(timeZone, offsetHours);

Use this to convert OffSet to postive:

var offset = new Date().getTimezoneOffset();
console.log(offset);
this.timeOffSet = offset + (-2*offset);
console.log(this.timeOffSet);

Once I had this "simple" task and I used (new Date()).getTimezoneOffset() - the approach that is widely suggested here. But it turned out that the solution wasn't quite right. For some undocumented reasons in my case new Date() was returning GMT+0200 when new Date(0) was returning GMT+0300 which was right. Since then I always use

(new Date(0)).getTimezoneOffset() to get a correct timeshift.

Why not just use:

function timezoneOffset(date: Date) {
  return 6000 * ((date.getUTCHours() - date.getHours()) * 60 + ((date.getUTCMinutes() - date.getMinutes())))
}

Here is the solution for finding the remote countries TimezoneOffset by just passing the timezone to the function. In this example 'Asia/Calcutta' is the timezone

function getTimezoneOffset(timezone) {
    LocalDate = new Date();
    LocalDate.setMilliseconds(0);

    const LocalOffset = LocalDate.getTimezoneOffset();
    RemoteLocaleStr = LocalDate.toLocaleString('en-US', {timeZone: timezone});
    RemoteDate = new Date(RemoteLocaleStr);
    diff = (LocalDate.getTime()-RemoteDate.getTime()) / 1000 / 60 ;

    RemoteOffset = LocalOffset + diff;
    return RemoteOffset;
}
console.log(getTimezoneOffset('Asia/Calcutta'));