Unit Conversion Quick Reference: Length, Weight, Temperature, Volume

Whether you’re cooking, traveling, or working with international specs, unit conversion comes up constantly. Here’s a practical reference for the most common conversions.

Length

Quick mental math:

• Miles to km: multiply by 1.6 (5 miles ≈ 8 km)
• Inches to cm: multiply by 2.5 (close enough for estimates)
• Feet to meters: divide by 3.3 (6 feet ≈ 1.83 m)

Weight

Quick mental math:

• Pounds to kg: divide by 2.2 (150 lbs ≈ 68 kg)
• Ounces to grams: multiply by 28 (4 oz ≈ 113 g)

Temperature

The formulas:

°F to °C: (°F - 32) × 5/9
°C to °F: (°C × 9/5) + 32
°C to K: °C + 273.15

Common reference points:

Quick mental math for °F to °C: Subtract 30, divide by 2. It’s approximate but useful: 80°F → (80-30)/2 = 25°C (actual: 26.7°C).

Volume

Cooking shortcuts:

• 1 cup ≈ 240 mL
• 1 tablespoon ≈ 15 mL
• 1 teaspoon ≈ 5 mL
• 1 gallon ≈ 3.8 liters

Why units are confusing

The US, UK, and metric systems overlap in confusing ways:

• US gallon (3.785 L) ≠ UK gallon (4.546 L)
• US fluid ounce (29.57 mL) ≠ UK fluid ounce (28.41 mL)
• A US ton (2000 lbs) ≠ a metric tonne (2204.6 lbs) ≠ an Imperial ton (2240 lbs)

Always specify which system you’re using when the audience might be international.

Digital storage

Most operating systems show “GB” but mean GiB (base 2), which is why your “1 TB” drive shows as ~931 GB.

A unit converter tool handles all these conversions instantly — pick the category, enter a value, and see the result. No formulas to remember.