Wochen Rechner – Wie viele Wochen zwischen Daten?
Berechne die Anzahl der Wochen zwischen zwei Daten oder finde ein Datum, das eine bestimmte Anzahl von Wochen entfernt ist. Kostenloser Datumsrechner.
How to Calculate Weeks Between Dates
The number of weeks between two dates is found by dividing the total number of days by 7. If the result isn't a whole number, you'll have a remainder of 1–6 extra days.
Method:
- Count the total calendar days between the start and end date (inclusive or exclusive depending on your purpose)
- Divide by 7 to get full weeks
- The remainder is the extra days beyond full weeks
Example: From January 1 to March 31 = 89 days = 12 weeks and 5 days.
The Gregorian calendar has a fixed relationship: 1 year = 52 weeks + 1 day (365 days), or 52 weeks + 2 days in a leap year (366 days). This is why your birthday falls one day later each year (or two days after a leap year).
Common Duration Reference in Weeks
Frequently needed time spans expressed in weeks:
| Duration | Days | Weeks | Common context |
|---|---|---|---|
| 1 month (avg) | 30.44 | 4.35 | Monthly planning |
| 1 quarter | 91 | 13 | Business/fiscal quarter |
| 6 months | 182–184 | 26 | Half-year |
| 1 year | 365/366 | 52.14 | Annual planning |
| 18 months | 547–548 | 78 | Product/startup milestone |
| Marathon training plan | 84 | 12 | Beginner 12-week plan |
| Half-marathon training | 56–84 | 8–12 | Typical training block |
| 5K training for beginners | 42–56 | 6–8 | Couch to 5K |
Weeks in Pregnancy, Training, and Planning
Weeks are the standard unit for tracking progress in several time-sensitive contexts:
Pregnancy: Counted from the first day of the last menstrual period (LMP). Full term = 40 weeks. Preterm = before 37 weeks. Post-term = after 42 weeks.
Running training blocks: Training is typically structured in 3–4 week mesocycles, where weeks 1–3 progressively increase load and week 4 is a recovery (deload) week. A typical marathon build: 16–20 weeks. A 5K build: 6–10 weeks.
Fiscal/financial planning: The ISO week numbering system (ISO 8601) numbers weeks 1–52 (or 53 in some years), with Week 1 starting on the Monday of the week containing the year's first Thursday.
Frequently Asked Questions
How many weeks are in a year?
A standard year has 52 weeks and 1 day (365 days ÷ 7 = 52.143 weeks). A leap year has 52 weeks and 2 days. For planning, most calendars treat a year as 52 working weeks.
How many weeks is 90 days?
90 days = 12 weeks and 6 days (90 ÷ 7 = 12.857 weeks). This is close to 3 calendar months.
How do I calculate how many weeks pregnant I am?
Count the days from the first day of your last menstrual period (LMP) to today, then divide by 7. For example, if your LMP was 70 days ago, you are 10 weeks pregnant.
How many weeks is 6 months?
Six months is approximately 26 weeks (182–184 days ÷ 7). The exact number varies because months have different lengths (28–31 days).
How long is a marathon training plan in weeks?
Beginner marathon plans typically run 16–20 weeks. Intermediate plans are 12–16 weeks. The most popular plans (Hal Higdon, Jack Daniels) are 18 weeks. The first week should start when you can comfortably run 8–10 miles (13–16 km) per week.
Weeks, Days, and Time Conversions
A week is exactly 7 days. One calendar year contains exactly 52 weeks and 1 day (365 days), or 52 weeks and 2 days in a leap year (366 days). This means New Year's Day advances by 1 day of the week each year, or 2 days after a leap year.
| Time Period | Weeks | Days | Hours |
|---|---|---|---|
| 1 month (avg) | 4.33 weeks | 30.44 days | 730.5 hrs |
| Quarter (3 months) | 13 weeks | 91.25 days | 2,191 hrs |
| 6 months | 26 weeks | 182.5 days | 4,380 hrs |
| 1 year | 52 weeks + 1 day | 365 days | 8,760 hrs |
| 2 years | 104 weeks + 2 days | 730 days | 17,520 hrs |
| 5 years | 261 weeks + 1 day | 1,826 days | 43,800 hrs |
Weeks are used in finance (52-week highs/lows), pregnancy (gestational age in weeks), project management (sprint durations), and sports seasons. ISO 8601 defines week numbering: week 1 is the week containing the first Thursday of the year, which always falls Jan 4–7.
How many weeks are in a year?
Exactly 52 weeks and 1 day (365 days ÷ 7 = 52.143 weeks). A leap year has 52 weeks and 2 days.
How many weeks are in 3 months?
Approximately 13 weeks (91 days ÷ 7 = 13). Quarter lengths in business are: Q1 (13 weeks), Q2 (13 weeks), Q3 (13 weeks), Q4 (13–14 weeks).
How many weeks are in 9 months of pregnancy?
40 weeks. Pregnancy is counted as 40 weeks from the last menstrual period, even though conception occurs at about 2 weeks. Full term is defined as 39–40 weeks.