Weeks from today

What Is a Weeks Calculator?

A weeks calculator converts a date range into its equivalent number of weeks and leftover days — or finds a target date by adding or subtracting a given number of weeks from a start date. It's the week-centric counterpart to a day calculator, and it's useful any time you plan in week-sized blocks rather than raw day counts.

Sprint planners use weeks calculators to size two-week sprints and fit them into a quarter. Physicians and midwives use them to track gestational age in weeks (pregnancy progresses from LMP to delivery in roughly 40 weeks). Personal trainers use them to structure 8- or 12-week training programs. Anywhere a schedule is naturally weekly, this calculator removes the manual division.

ToolYard's weeks calculator runs in your browser — no data is sent to a server, and results appear instantly.

How to Use This Weeks Calculator

1. Choose Weeks Between Dates or Add/Subtract Weeks mode.
2. For Weeks Between: enter a Start Date and End Date. The result shows full weeks and remaining days.
3. For Add/Subtract: enter a Start Date and the number of weeks to add or subtract. The result shows the target date.
4. Toggle Business Weeks Only to exclude weekends from the calculation.
5. Read the full breakdown — days, weeks, months — in the result panel.

Worked Example: 12-Week Training Program

Coach Dana starts a client on a 12-week strength program beginning February 3, 2025.

• 12 weeks × 7 days = 84 days
• End date: February 3 + 84 days = April 28, 2025
• Calendar breakdown: Feb 3–28 (25 days) + March (31) + April 1–28 (28) = 84 days ✓
• Business weeks: 12 weeks × 5 days = 60 training days (excluding weekends)
• Program spans parts of 3 calendar months (February, March, April)

Dana can now schedule exactly 4 weekly check-ins per month and build deload weeks at weeks 4, 8, and 12 without any manual calendar counting.

Common Time Periods in Weeks

Business days exclude Saturday and Sunday. Add public holidays manually for exact working-day counts.

Key Concepts: Weeks, ISO Week Numbers, and Pregnancy Weeks

Full weeks vs. partial weeks — "3 weeks and 4 days" is 25 days total. A calculator that returns only "3 weeks" is truncating — confirm whether the output shows the remainder.

ISO week numbering — The ISO 8601 standard defines Week 1 as the week containing the first Thursday of the year. Week 1 of 2025 starts on Monday, December 30, 2024. This matters for cross-year sprint planning.

Gestational age in weeks — Pregnancy is measured from the Last Menstrual Period (LMP). At 40 weeks (280 days) from LMP, the due date is reached. Each 7-day span is one gestational week.

Business weeks — A business week is Monday–Friday (5 days). To find business weeks between dates, count total days, subtract weekend days (2 per week), and divide by 5.

Tips and Common Mistakes

• Confusing "in X weeks" with "X weeks from now" — "In 2 weeks" from Monday March 3 is Monday March 17 (14 days later). "After 2 weeks" could mean the start of week 3 (March 17) or the end (March 23). Specify start vs. end of the interval.
• Ignoring the remainder — 30 days is 4 weeks and 2 days, not 4 weeks. Always check the leftover days when scheduling around week-sized blocks.
• Sprint calendar drift — If you schedule 6 × 2-week sprints starting January 6, the last sprint ends June 15 — not end of June. Use the calculator to pin exact sprint start/end dates before committing the team calendar.
• Gestational week confusion — Gestational age is measured from LMP, not conception. Conception typically occurs 2 weeks after LMP, so "10 weeks pregnant" means 8 weeks post-conception.
• Year-boundary weeks — The last week of December and first week of January share ISO week numbers across years. Always specify the year when communicating week numbers.

Frequently Asked Questions

Related Tools