CalculatorCast
מתמטיקה פיננסים בריאות וכושר תאריך ושעה ממירי יחידות מחשב פיזיקה כימיה בנייה הנדסה סטטיסטיקה חינוך חיי יומיום ביולוגיה רכב בישול ומזון ספורט וכושר נדל"ן צילום חשמל חקלאות נסיעות עסקים
כל המחשבונים מועדפים ()
English Español Français Deutsch Português Italiano Nederlands Polski Türkçe 日本語 한국어 Svenska Norsk Dansk Suomi עברית

מחשבון רווח סמך

רווח סמך לממוצע עם סטיית תקן ידועה.

מבוא

Confidence Interval Calculator — CI for a mean with known standard deviation. Enter Sample mean, Std. deviation, Sample size, Confidence level to get an instant, accurate result.

נוסחה

Margin of error = z × (sd/√n). Interval = mean ± margin of error, where z is the critical value for the chosen confidence level (1.645/1.96/2.576 for 90/95/99%).

צעד אחר צעד

  1. Enter the Sample mean.
  2. Enter the Std. deviation.
  3. Enter the Sample size.
  4. Enter the Confidence level.
  5. Click Calculate to see your result instantly.

דוגמה מהעולם האמיתי

Example: With Sample mean = 100, Std. deviation = 15, Sample size = 30, Confidence level = 95, the Confidence Interval Calculator gives Lower: 94.6324, Upper: 105.3676, Margin Error: 5.3676.

שאלות נפוצות

What does a 95% confidence interval mean?
If you repeated the sampling many times, about 95% of the resulting intervals would contain the true population mean.
Why does a larger sample size narrow the interval?
The margin of error shrinks as sample size increases, since √n grows in the denominator.
What inputs does the Confidence Interval Calculator need?
You'll need to provide: Sample mean, Std. deviation, Sample size, Confidence level. All fields use sensible defaults, so you can see a working example immediately and then adjust the values to match your own numbers.
How accurate is the Confidence Interval Calculator?
The Confidence Interval Calculator applies the formula exactly as calculated — Margin of error = z × (sd/√n). Interval = mean ± margin of error, where z is the critical value for the chosen confidence level (1.645/1.96/2.576 for 90/95/99%). — so results are precise for the inputs you provide. Accuracy depends on entering correct, realistic input values.
Is the Confidence Interval Calculator free to use?
Yes, the Confidence Interval Calculator is completely free, requires no signup, and runs instantly in your browser.

אודות מחשבון רווח סמך

The Confidence Interval Calculator uses a real, verifiable formula — Margin of error = z × (sd/√n). Interval = mean ± margin of error, where z is the critical value for the chosen confidence level (1.645/1.96/2.576 for 90/95/99%). — so results are accurate every time, not an approximation.