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- Fitness
How Much Water Should You Drink a Day? A Real Formula
Weight-based daily water intake formula with a worked example and a full reference table by body weight, activity, and climate.
July 4, 2026 - Calculators
How Old Am I? The Exact Age Formula (Years, Months, Days)
Find out exactly how old you are with a free age calculator. Learn the real formula behind 'how old am I' in years, months and days, with a worked example.
July 4, 2026 - Calculators
How to Calculate Aspect Ratio (Formula, Common Ratios, and Resizing Without Distortion)
The aspect ratio formula, a cheat sheet of common video and social ratios, and how to resize an image without stretching it. Free calculator included.
July 4, 2026 - Fitness
How to Calculate Your Body Fat Percentage (US Navy Method)
Learn the US Navy body fat formula, see a full worked example, and find your category. Free calculator included.
July 4, 2026 - Productivity
How to Calculate Days Between Two Dates (With Worked Examples)
Find the exact days, weeks, or months between two dates and see why a 'year' isn't always 365 days. Free date difference calculator included.
July 4, 2026 - Fitness
How to Calculate Running Pace (With a Real Example)
Learn the running pace formula, see a full worked example in km and miles, and check a race-time table for 5K to marathon. Free calculator included.
July 4, 2026 - Finance
How to Calculate VAT (Add or Remove Tax From Any Price)
The VAT add and remove formulas, a worked invoice example, a UK rate table, and the mistakes that throw off a tax return. Free calculator included.
July 4, 2026 - Fitness
How to Calculate Your Ideal Weight (Devine, Robinson, Miller, Hamwi)
Learn the four classic ideal body weight formulas, see two full worked examples, and check the height reference table. Free calculator included.
July 4, 2026