One common base. Consistent answers.
For proportional units, convert the input to a base unit, then divide by the target unit’s factor. For example, an international foot is defined as exactly 0.3048 meters, and an inch is exactly 0.0254 meters. Dividing 0.3048 by 0.0254 gives 12 inches per foot.
WeZual uses one set of factors in both directions, rather than separate rounded multipliers. This keeps reciprocal conversions consistent. Try feet to inches.
Precision is not the same as accuracy.
The calculator offers 4, 6, 10, or 15 significant digits. Significant digits count the meaningful digits from the first nonzero digit, rather than the digits after the decimal point. For example, 12345 rounded to 4 significant digits is 12350.
Results are calculated using JavaScript’s double-precision numbers, then rounded for display. A defined factor may be exact, but floating-point arithmetic and displayed results can still contain rounding. Extremely small or large outputs use scientific notation. Numerical overflow and underflow produce an error instead of a misleading answer.
A conversion cannot improve the precision of the original measurement. If a length was measured only to the nearest centimeter, a long decimal answer in inches does not make that measurement more exact.
A gallon is not always the same gallon.
A US liquid gallon is exactly 3.785411784 liters. An imperial (UK) gallon is exactly 4.54609 liters. US and UK pints and fluid ounces also differ. We label the system on each unit so you can choose deliberately.
A US customary cup is 236.5882365 mL; a metric cup is 250 mL. These are volume measurements. Converting a cup of flour into grams requires the flour’s density, packing, and measuring method; a volume converter cannot supply that information. Explore volume units.
Temperature needs a zero-point adjustment.
Celsius and Fahrenheit do not start at the same zero. The formula is °F = °C × 9/5 + 32. Kelvin is related to Celsius by K = °C + 273.15. That is why a single multiplication does not convert absolute temperatures correctly.
Temperature differences are a different task: a change of 10 °C equals a change of 18 °F, without adding 32. Our temperature calculator converts absolute temperatures and rejects values below absolute zero. Try Celsius to Fahrenheit.
Bits, bytes, and binary prefixes.
One byte contains eight bits. Case matters: b denotes bit and B denotes byte. Decimal prefixes use powers of 1,000: 1 GB is 1,000,000,000 bytes. Binary IEC prefixes use powers of 1,024: 1 GiB is 1,073,741,824 bytes.
A connection rated at 100 Mbit/s has a theoretical data rate of 12.5 MB/s. Actual file transfers also depend on network overhead and device performance. Convert network speeds.
Calendar months are not fixed durations.
A minute is 60 seconds, an hour is 3,600 seconds, and a day in this duration calculator is 86,400 seconds. We use a Julian year of exactly 365.25 days and an average month of one twelfth of that year: 30.4375 days.
This convention supports consistent duration conversions. It does not calculate elapsed time between calendar dates, account for leap seconds, or predict the length of a particular month. Explore time conversions.
References and conventions
- NIST Guide to the SI: conversion factors by quantity
- BIPM: The International System of Units
- NIST: metric prefixes
These tools are for general reference. For precision-critical work, use the governing standard, original measurement uncertainty, and the unit convention required by your task.