Calculators— Guides & Articles

• How to Calculate Oval Perimeter Using Semi-Axes

  Published 2026-08-19

  Find the perimeter of any oval from its two semi-axes. The Ellipse Area Calculator returns Ramanujan's perimeter approximation plus area and eccentricity.

  

• Dog Years to Human Years: The AKC Size Chart Method

  Published 2026-08-18

  Convert dog years to human years using the AKC size-based chart endorsed by the AVMA. Enter your dog's age and adult size — the result appears instantly.

  

• How to Convert Density to Mass in Any Unit

  Published 2026-08-18

  Convert density to mass units across metric and imperial systems. Free tool handles g/cm³, kg/m³, lb/ft³, lb/gal and more — no uploads.

  

• How to Calculate the Day Number of Any Year

  Published 2026-08-18

  Find the day number of any date with our free calculator. Includes ISO 8601 week numbers, days remaining, and leap year status.

  

• Day of the Week Calculator: Reference-Verified Accuracy

  Published 2026-08-18

  Find the exact weekday for any date with an accurate day of the week calculator. Cross-checked against Zeller's congruence with full leap-year handling.

  

• How to Convert Date Format in SQL: CONVERT, CAST, FORMAT

  Published 2026-08-18

  Convert date format in SQL with CONVERT, CAST, FORMAT. SQL Server style codes 101, 103, 120 explained, plus ISO 8601 for portable inserts.

  

• Google Sheets Date Difference: 3 Reliable Methods

  Published 2026-08-18

  Need a date difference in Google Sheets? Use DATEDIF for unit breakdowns or simple subtraction for raw days, or try a free tool for a complete instant answer.

  

• Add Days to a Date for Chart Rows and Milestones

  Published 2026-08-18

  Add days to any date for chart planning with calendar-accurate results. Learn the exact steps, leap-year rules, and end-of-month clamping so your chart…

  

• Convert Storage Values Stored as Text in Excel

  Published 2026-08-18

  When Excel cells hold storage sizes like "1.5 GB" as text, formulas break. Here's how to fix them and convert units with the free Data Storage Converter.

  

• Calculate Cylinder Volume in kg Using Density

  Published 2026-08-18

  To turn cylinder dimensions into kg, multiply volume by density. Use V = πr²h to find cubic meters, then multiply by density in kg/m³.