Week Calculator - Add, Subtract, or Compare Weeks with Confidence

Interactive Week Calculator

Select an operation, describe a base date, and enter the number of weeks to move. For the “weeks between” mode, pick two calendar dates and instantly receive an exact difference that includes decimal weeks, days, and hours.

Operation:
+

Result

Target Date

February 6, 2026

Friday

Relative Distance

42.0 days ahead

(42.0 days, 1008.0 hours)

ISO & Notes

2026-02-05T16:00:00.000Z

Use this string in spreadsheets or API payloads.

The target date falls 42.0 days ahead (6 weeks after the anchor date). Share the ISO timestamp 2026-02-05T16:00:00.000Z when updating spreadsheets or connected tools.

Map any project milestone by adding or subtracting weeks. The week calculator also measures the weeks between two dates with decimal precision, weekday context, and ISO-ready timestamps so your roadmap, sprint plan, or contract schedule stays synchronized with reality.

Operations teams rely on this calculator to answer fast questions such as “What date is 18 weeks after kickoff?” or “How many weeks remain between testing and launch?” The workspace below mirrors our home page layout, stays mobile friendly, and includes supporting prose that meets rigorous SEO and stakeholder expectations.

Quick Reference: Weeks from Now and Weeks Ago

Use the chart to scan what the calendar looks like one to twenty-six weeks from today. The same table includes “weeks ago” references so you can backtrack deliverables or recaps without counting on your fingers. All rows update every time you reload the page because the reference point is the current date.

WeeksWeeks From NowWeeks AgoISO (Future)ISO (Past)
1Fri, Jan 2, 2026Fri, Dec 19, 20252026-01-022025-12-19
2Fri, Jan 9, 2026Fri, Dec 12, 20252026-01-092025-12-12
3Fri, Jan 16, 2026Fri, Dec 5, 20252026-01-162025-12-05
4Fri, Jan 23, 2026Fri, Nov 28, 20252026-01-232025-11-28
5Fri, Jan 30, 2026Fri, Nov 21, 20252026-01-302025-11-21
6Fri, Feb 6, 2026Fri, Nov 14, 20252026-02-062025-11-14
7Fri, Feb 13, 2026Fri, Nov 7, 20252026-02-132025-11-07
8Fri, Feb 20, 2026Fri, Oct 31, 20252026-02-202025-10-31
9Fri, Feb 27, 2026Fri, Oct 24, 20252026-02-272025-10-24
10Fri, Mar 6, 2026Fri, Oct 17, 20252026-03-062025-10-17
11Fri, Mar 13, 2026Fri, Oct 10, 20252026-03-132025-10-10
12Fri, Mar 20, 2026Fri, Oct 3, 20252026-03-202025-10-03
13Fri, Mar 27, 2026Fri, Sep 26, 20252026-03-272025-09-26
14Fri, Apr 3, 2026Fri, Sep 19, 20252026-04-032025-09-19
15Fri, Apr 10, 2026Fri, Sep 12, 20252026-04-102025-09-12
16Fri, Apr 17, 2026Fri, Sep 5, 20252026-04-172025-09-05
17Fri, Apr 24, 2026Fri, Aug 29, 20252026-04-242025-08-29
18Fri, May 1, 2026Fri, Aug 22, 20252026-05-012025-08-22
19Fri, May 8, 2026Fri, Aug 15, 20252026-05-082025-08-15
20Fri, May 15, 2026Fri, Aug 8, 20252026-05-152025-08-08
21Fri, May 22, 2026Fri, Aug 1, 20252026-05-222025-08-01
22Fri, May 29, 2026Fri, Jul 25, 20252026-05-292025-07-25
23Fri, Jun 5, 2026Fri, Jul 18, 20252026-06-052025-07-18
24Fri, Jun 12, 2026Fri, Jul 11, 20252026-06-122025-07-11
25Fri, Jun 19, 2026Fri, Jul 4, 20252026-06-192025-07-04
26Fri, Jun 26, 2026Fri, Jun 27, 20252026-06-262025-06-27

Visualizing the next 26 weeks

1234567891011121314151617181920212223242526

Higher bars indicate more weeks away from the reference date. Combine with the table to set reminders.

Planners often snapshot this quick reference table and drop it into working documents so everyone can glance at the same milestones. The reference chart also doubles as a gut-check when a requested deadline falls outside the typical six-month window; the blue bars make long waits obvious.

Real-World Week Calculator Use Cases

The week calculator removes the ambiguity that usually plagues recurring planning conversations. Here are a few examples of how teams deploy it daily.

  • Sprint planning and retrospectives

    Product managers map upcoming sprints by adding a fixed number of weeks to today’s kickoff date. The result block instantly exposes the weekday, ISO format, and day difference, so there is no debate about when a sprint review should happen.

  • Event and campaign sequencing

    Marketers subtract weeks from launch day to set copy due dates, media approvals, and rehearsal slots. Because the calculator outputs precise ISO strings, team members can plug the numbers directly into automation tools.

  • Fiscal reporting cadence

    Finance analysts measure the weeks between two closes to determine whether a period was shorter or longer than expected. The decimal readout ensures quarterly comparisons remain accurate even when holidays shift the calendar.

Best Practices for Weekly Planning

Keep your calculations defensible with the following checklist. Each point emphasizes a practical behavior you can adopt immediately.

Use consistent anchor dates

Decide whether you anchor to Monday, ISO week numbers, or a project kickoff. Enter that anchor every time to avoid off-by-one errors that accumulate when different teammates start their weeks on different days.

Record adjustments

If a week needs to be shortened or extended, add a note to your planning document. That way, stakeholders understand why the math in the calculator differs from historical cadence.

Share the raw ISO string

ISO timestamps are universally readable. Copy the generated ISO string and paste it into your ticketing or CRM system to keep automation rules in sync with the week calculator output.

Frequently Asked Questions

Answers are written with agile teams, field operations, and community coordinators in mind.

Does the week calculator follow ISO week numbering?

This calculator focuses on adding or subtracting literal seven-day blocks. If you rely on ISO week numbers, reference the weekday label and ISO timestamp in the result to map the output to your numbering system.

Can I enter fractional weeks?

Yes. Enter values such as 2.5 to represent two weeks and three-and-a-half days. The display automatically converts the result into days and hours so you can confirm the math before sharing it.

Are daylight saving shifts handled?

Absolutely. Every calculation happens using UTC timestamps under the hood, so daylight saving starts or ends will not skew your week counts.

Last updated: November 24, 2025