Ship-by date calculator
Enter the promised delivery date and the carrier's transit in working days to get the latest day to ship: for delivery on Monday 27 July 2026 with five working days, ship by Monday 20 July. Weekends never count. Free in your browser.
- Free
- Runs in your browser
- No sign-up
- Your data stays on your device
Run — free
Worked example
- Delivery date
- 2026-07-27
- Transit days
- 5
- Ship by date
- 2026-07-20
- Ship by weekday
- Monday
- Delivery weekday
- Monday
- Ship by iso weekday
- 1
A ship-by date calculator answers the fulfillment question every storefront and warehouse planner faces: if the customer must receive the order by a fixed promised delivery day and the carrier needs a known number of working days in transit, what is the latest calendar day you can still hand the package to the carrier? Enter a strict ISO delivery date and a non-negative integer transit workday count—for example delivery on Monday the twenty-seventh with five working days of transit—and the tool walks backward on the Gregorian calendar while skipping every Saturday and Sunday, then returns the ship-by ISO date, weekday names, ISO weekday numbers, and the calendar span between ship and delivery. Public holidays are intentionally out of scope so regional calendars do not silently rewrite a global SLA.
What ship-by means with working-day transit
E-commerce and B2B fulfillment almost never schedule shipping with raw calendar days alone. A promise of three working days of ground transit from a Monday ship day typically means the package should arrive on Thursday under a Monday-through-Friday carrier calendar, not on Wednesday counting every calendar day including weekends.
Saturdays and Sundays never count toward transit and are never chosen as intermediate stop points of the walk when transit is greater than zero; when transit is zero the ship-by date equals the delivery date even if that day falls on a weekend, which keeps reverse checks honest against forward add-working-days tools. The delivery date itself is not consumed as one of the transit steps: five working days before a Monday lands on the previous Monday, matching the inverse of adding five working days forward.
Public holidays, blackout days, and regional rest calendars are intentionally omitted because they vary by country, carrier, and warehouse; baking a single holiday table into a generic tool would wrong teams that ship on different calendars. Pair the result with your own holiday list when a mid-week public holiday must also be skipped.
Where it fits in real workflows
Operations teams set warehouse cut-off times from marketing delivery promises: if checkout advertises delivery by Friday with two working days of transit, the latest ship-by must land on Wednesday, and this call makes that date explicit before orders are accepted. Marketplaces and multi-carrier dashboards convert each listing’s transit SLA into a single ship-by date per order so pick-and-pack queues stay aligned. Finance and customer-care tools recompute the same ship-by when a customer asks whether an order still can make a gift date.
The browser path is free for interactive checks: paste a promised arrival, enter three, and confirm the ship day before hard-coding a campaign calendar. Combine the output with your own holiday tables when a region observes mid-week public holidays; this tool remains the reliable weekend filter underneath. Distinct search intent from simply adding working days forward or counting business days between two project bounds: here the product question is specifically “latest day I may still ship.”
What you can do with it
Checkout delivery promises
Convert a storefront “arrives by Friday” promise and a known carrier transit SLA into the latest warehouse ship-by date before the order is accepted.
Gift and event deadlines
Given a hard gift date and transit working days, tell customers the last day they can still place an order that ships on time.
FAQ
What does it cost?
The same calculation runs free in your browser on this page.
Are transit days working days or calendar days?
Working days. Only Monday through Friday count. Saturdays and Sundays are skipped when walking backward from the delivery date.
Are public holidays skipped?
No. Only Saturdays and Sundays are skipped. Apply your own holiday list if a region or carrier needs it.
Why was my date rejected?
The delivery date must be a real Gregorian calendar day in strict YYYY-MM-DD form.
What happens if transit is zero days?
The ship-by date is then the delivery date itself, even when that day falls on a weekend. This keeps the result consistent with adding working days forward from a ship date.
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/ship-by-date \
-H "Authorization: Bearer $KIT_KEY" \
-H "Content-Type: application/json" \
-d '{"delivery_date":"2026-07-27","transit_days":5}'const res = await fetch("https://api.kit.forhosting.com/date/ship-by-date", {
method: "POST",
headers: {
"Authorization": `Bearer ${process.env.KIT_KEY}`,
"Content-Type": "application/json"
},
body: JSON.stringify({
"delivery_date": "2026-07-27",
"transit_days": 5
})
});
const { task_id } = await res.json();import os, requests
res = requests.post(
"https://api.kit.forhosting.com/date/ship-by-date",
headers={"Authorization": f"Bearer {os.environ['KIT_KEY']}"},
json={
"delivery_date": "2026-07-27",
"transit_days": 5
},
)
task_id = res.json()["task_id"]<?php
$res = file_get_contents("https://api.kit.forhosting.com/date/ship-by-date", false, stream_context_create([
"http" => [
"method" => "POST",
"header" => "Authorization: Bearer " . getenv("KIT_KEY") . "\r\nContent-Type: application/json",
"content" => '{"delivery_date":"2026-07-27","transit_days":5}',
],
]));
$task = json_decode($res, true);body := bytes.NewBufferString(`{"delivery_date":"2026-07-27","transit_days":5}`)
req, _ := http.NewRequest("POST", "https://api.kit.forhosting.com/date/ship-by-date", body)
req.Header.Set("Authorization", "Bearer "+os.Getenv("KIT_KEY"))
req.Header.Set("Content-Type", "application/json")
res, _ := http.DefaultClient.Do(req)Example request
{
"delivery_date": "2026-07-27",
"transit_days": 5
}Example response
{
"task_id": "tsk_a1b2c3d4e5f6a1b2c3d4e5f6",
"type": "date.ship_by_date",
"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
What ship-by means with working-day transit
This capability models that contract explicitly: transit_days is a count of Monday through Friday steps only, and the algorithm starts from the promised delivery_date and steps one calendar day at a time into the past until it has consumed exactly that many non-weekend days.
How to call it and read the result
Because the algorithm never consults the local timezone, a pure calendar value stays pure and does not slip by a day when a server runs in another zone. Send two fields: delivery_date as a strict YYYY-MM-DD string for the promised customer arrival day, and transit_days as a non-negative integer for the carrier working-day transit. Aliases such as delivery, due, promise_date, arrive_by, and target_date for the date, and transit, shipping_days, lead_days, and days for the integer, are accepted so existing forms map cleanly without renaming fields. Invalid calendar dates fail immediately with invalid_input: the thirtieth of February, month thirteen, free-form strings, and non-canonical padding are rejected rather than coerced. A negative transit count, a non-integer, or a value above the hard ceiling is also invalid_input so a runaway loop cannot exhaust the isolate. A successful response returns ship_by_date (the latest day to tender the package), the echoed delivery_date, the transit_days applied, ship_by_weekday and delivery_weekday as English weekday names, ship_by_iso_weekday and delivery_iso_weekday as Monday-equals-one through Sunday-equals-seven numbers, calendar_days as the absolute Gregorian span from ship-by to delivery (which is at least transit_days and larger whenever weekends were skipped), and a short formula string documenting the rule. Use the weekday fields in user-facing copy and cut-off banners; use the ISO ship_by_date as the system of record for pick waves, carrier cut-offs, and SLA engines. Pricing is a flat $0.002 per successful request with unit item; failed validation is never charged.
Where it fits in real workflows
Developers embed the identical solve in webhooks and CRON jobs so every service shares one definition of latest ship day instead of reimplementing ad-hoc loops that disagree on Friday-to-Monday edges. The API path costs $0.002 per successful request and is billed per item, which keeps bulk order-planning scripts cheap while still covering edge execution.
Integration use cases
Pick-wave and carrier cut-offs
Batch orders by ship_by_date so pick waves and carrier handoffs never miss the working-day transit window.
Technical questions
What if transit_days is zero?
ship_by_date equals delivery_date, even when that day falls on a weekend. Use a positive transit count when the carrier needs working days in motion.