Is a weekend day?
Type one date and get a clear yes or no on whether it falls on Saturday or Sunday: 25 July 2026 is a Saturday, so it is a weekend day. You also get the weekday name and its ISO number. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Date
- 2026-07-25
- Year
- 2,026
- Month
- 7
- Day
- 25
- Day name
- Saturday
An is-a-weekend-day checker answers a question that schedulers, payroll tools, and classroom calendars ask constantly: given one calendar date, does it fall on Saturday or Sunday?
What counts as a weekend day and how the date is interpreted
The input is a single ISO calendar date written as four digits for the year, a hyphen, two digits for the month, another hyphen, and two digits for the day—for example twenty twenty-six dash zero seven dash twenty-five. That form is unambiguous across locales that write month-first or day-first in everyday prose, which is why APIs and databases prefer it.
There is no time-of-day and no trailing Z, so the result is the weekend status of that explicit civil day and does not depend on the caller’s timezone or the host clock. Underneath, the Gregorian calendar rules still apply: months have fixed lengths except February, which has twenty-nine days only in leap years (years divisible by four, except century years not divisible by four hundred).
The weekday is computed with Sakamoto’s integer formula, which yields a Sunday-origin index that is mapped to English long and short names and to the ISO weekday number.
Practical tips, limits, and when to pick this tool
Always send a full calendar date, not a datetime with a time component or a trailing Z; this tool deliberately refuses extended ISO timestamps so callers cannot accidentally encode timezone-dependent midnights. When teaching or testing, keep a small known set: a Saturday success case, a Sunday success case, a mid-week false case such as a Friday or Wednesday, a leap-day success case such as a valid twenty-ninth of February, and a deliberate failure such as twenty twenty-three dash zero two dash twenty-nine.
Year bounds stop at nine thousand nine hundred ninety-nine to keep four-digit ISO strings well defined for this product surface. This landing targets people searching for is a weekend day, weekend day checker, or is Saturday or Sunday online; it is not a business-day counter, not a range weekend tally, and not a locale-aware date formatter.
What you can do with it
Scheduler and blackout-date checks
Confirm that a proposed delivery or maintenance window falls on Saturday or Sunday before locking a calendar hold.
FAQ
What date format do I need?
A single ISO calendar date as YYYY-MM-DD (for example 2026-07-25). Datetimes, ordinal dates, and week dates are not accepted.
Does the result depend on my timezone?
No. The solver uses pure Gregorian arithmetic on an explicit civil date and never reads the host clock or Date timezone.
What happens with an invalid date like 2023-02-29?
Invalid months, zero days, and non YYYY-MM-DD shapes are also rejected.
Is the weekend day checker free?
The browser tool is free and runs locally.
Can it use a Friday and Saturday weekend?
No. It uses the standard Saturday and Sunday weekend: either of those days gives yes, and Monday to Friday gives no. Counting weekend days between two dates or skipping them in a deadline are separate calculations.
Related tools
For developers — API access
Everything on this page is available programmatically. This section is for teams who want to wire it into their own systems; everyone else can just use the tool above.
API endpoint
Prefer to automate it? One authenticated POST creates the task; the result comes back by webhook or a signed link. The same capability also runs here on the web, by email and from Telegram — and soon from our app too.
Call it from your stack
curl -X POST https://api.kit.forhosting.com/date/is-weekend \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"date":"2026-07-25"}'const res = await fetch("https://api.kit.forhosting.com/date/is-weekend", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"date": "2026-07-25"
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/date/is-weekend",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"date": "2026-07-25"
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/date/is-weekend", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"date":"2026-07-25"}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"date":"2026-07-25"}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/date/is-weekend", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"date": "2026-07-25"
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "date.is_weekend",
"status": "queued",
"_links": {
"result": "/tasks/tsk_…/result"
}
}The API is asynchronous: the call returns a task_id immediately and the result arrives by webhook. Polling is capped at 1 req/s per task.
Pricing
Published price — no tokens, no invented credits. A failed task is never charged.
Errors
| HTTP | Code | Meaning |
|---|---|---|
401 | unauthorized | Missing or invalid API key. |
402 | insufficient_balance | Your balance doesn't cover the task price. |
404 | unknown_type | That task type doesn't exist. |
429 | rate_limited | Too many requests. Use the webhook instead of polling. |
Technical notes
Paste an ISO date in year-month-day form and this tool returns a clear boolean is_weekend flag, the English weekday name, the ISO weekday number (Monday equals one through Sunday equals seven), and a short message that states whether the day is a weekend day or a weekday. Invalid strings—wrong shape, impossible months, or a twenty-ninth of February outside a leap year—are rejected with a clear invalid_input error instead of a silent false.
What counts as a weekend day and how the date is interpreted
This capability uses the standard Saturday–Sunday weekend: if the civil weekday is Saturday or Sunday, is_weekend is true; if it is Monday through Friday, is_weekend is false. Related tools answer different search intents: a day-of-week calculator returns the full name without a weekend boolean, a weekend-count tool tallies Saturdays and Sundays between two dates, and a workday adder skips weekends when projecting a deadline—none of those replace a one-date boolean weekend check.
How to call the API and what comes back
The value must match the exact pattern of four digits, hyphen, two digits, hyphen, two digits, and must represent a real Gregorian day in the inclusive year range from one through nine thousand nine hundred ninety-nine. Send a JSON body with one required string field named date, which may also be supplied under the aliases iso_date, value, or day. On success the response echoes the canonical date string, year, month, and day as numbers, sets is_weekend and weekend to the same boolean, sets is_weekday to the opposite boolean, sets day_name and day_name_short to English labels such as Saturday and Sat, sets iso_weekday to the Monday-through-Sunday integer from one through seven, sets weekday_0_sunday to the zero-through-six Sunday-origin index, sets leap_year for the year, and includes a short message plus an ordered steps array that restates the parse, Sakamoto classification, and weekend test. Failed validation—missing field, non-string type, bad shape, out-of-range year, impossible month or day, or a non-leap twenty-ninth of February—returns invalid_input and is never charged. Pricing is a flat $0.002 per successful request with unit item.
Practical tips, limits, and when to pick this tool
Prefer the primary field name date when you control the client; aliases exist for compatibility with forms that label the control iso_date or value. Round-trip checks are easy: recompute the weekday with another trusted Gregorian source and confirm that Saturday and Sunday alone set is_weekend true. Prefer this capability when you already have one ISO date and only need a boolean weekend flag; if you need localized month names or formatted strings for many locales, use a date formatting capability instead.
Integration use cases
Weekend-only fixture generation for tests
Engineering teams build known Saturday/Sunday and weekday ISO dates for UI calendars without depending on the host clock.
Homework and calendar exercises
Students enter a textbook ISO date and compare a boolean weekend answer against hand-written weekday classification.
Technical questions
What counts as a weekend day?
Saturday and Sunday only. Monday through Friday return is_weekend false (is_weekday true).