Unit Converter — Metric and Imperial Length, Weight, Temperature

Everyday conversion errors are rarely exotic. They are “250” written without noticing it was millimeters, or an oven recipe followed in the wrong temperature scale. A Unit Converter removes factor lookup; you still choose the right category and unit pair.

Length and mass — multiply (carefully)

Examples of standard relationships:

• 1 inch = 2.54 cm
• 1 mile ≈ 1.60934 km
• 1 kg ≈ 2.20462 lb

The danger sits in prefixes:

| Written | Means | Common misread | |---------|-------|----------------| | 250 mm | 0.25 m | 250 m | | 1.5 kg | 1500 g | 1.5 g | | 3 cm | 0.03 m | 3 m |

If a result feels ~10× or ~1000× off, check prefixes before blaming the converter.

Temperature is a different animal

Celsius and Fahrenheit do not share a zero, and Kelvin shifts Celsius by 273.15.

• °F = (°C × 9/5) + 32
• °C = (°F − 32) × 5/9
• K = °C + 273.15

Rough kitchen mnemonics exist (“double and add 30”) but they are approximate — use exact formulas for medicine-adjacent or lab-adjacent work (and follow professional guidance where required). This article is general math only.

Area and volume traps

Converting 10 m² to ft² is not “multiply by 3.281.”
3.281 converts meters to feet. For square meters, use (3.281)² ≈ 10.76 as the factor — or convert each side to feet, then multiply.

Workflow for DIY:

1. Convert all sides to one linear unit
2. Compute area with the Area Calculator
3. Apply waste percent afterward

Travel and fuel

Align distance units before economy math. Miles with MPG or kilometers with L/100km — then open the Fuel Cost Calculator. Mixed systems are a frequent road-trip budgeting bug.

When a web converter is enough — and when it is not

Enough: homework, recipes, luggage limits, DIY shopping lists.
Not enough: legal trade measurement, calibrated lab work, or regulated dosing — those need certified processes and instruments.

Limitations

Display rounding can hide digits. Specialized units may be absent. Treat outputs as everyday mathematical conversions — see the Disclaimer.

Pick the category first, read the unit abbreviations twice, then convert with the Unit Converter. That two-second label check prevents most “why is this ten times too big?” moments.