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Quick Reference
Convert any unit or currency instantly — all in one clean tool.
Quick Reference
Transfer currency at mid-market rates with no hidden charges. Used by millions worldwide.
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Whether you're converting kilometers to miles for a road trip, grams to ounces for a recipe, or Celsius to Fahrenheit for a weather check, switching between measurement systems is a daily friction point for millions of people. Our unit converter handles eight distinct categories — length, mass, temperature, volume, area, speed, digital storage, and time — all in one place, without switching tools.
Each conversion uses precise mathematical factors based on the International System of Units (SI). Length conversions are anchored to the meter: one kilometer is exactly 1,000 meters, one inch is exactly 0.0254 meters, one mile is exactly 1,609.344 meters. Mass conversions are anchored to the kilogram: one pound is exactly 0.45359237 kilograms, one ounce is exactly 28.349523125 grams.
Temperature conversions use the correct affine formula rather than a simple multiplication, so -40 degrees Celsius equals -40 degrees Fahrenheit, and the freezing point stays fixed at 0 degrees Celsius regardless of how many times you convert back and forth. The converter also supports Kelvin (used in science and engineering) and Rankine (used in some US engineering contexts).
Live currency APIs require server infrastructure. To keep this tool fully client-side and always available offline, we embed approximate mid-market rates for 30 major currencies, labeled with their reference date. If you're doing serious financial planning, tap "Edit Rates" and type in the current rate from your bank or Google Finance — your edits are saved locally in your browser and override the defaults until you reset them.
The currency panel covers the US Dollar, Euro, British Pound, Japanese Yen, Canadian Dollar, Australian Dollar, Swiss Franc, Chinese Yuan, Indian Rupee, Mexican Peso, Brazilian Real, South Korean Won, Singapore Dollar, Hong Kong Dollar, and 16 more frequently traded currencies including the Norwegian Krone, Swedish Krona, Turkish Lira, Saudi Riyal, UAE Dirham, Thai Baht, Malaysian Ringgit, Indonesian Rupiah, Philippine Peso, Pakistani Rupee, Vietnamese Dong, Polish Zloty, and Czech Koruna.
All currency conversion works through a USD base: your input amount is converted to USD first, then from USD to the target currency. This means any pair of the 30 currencies can be converted without storing 870 separate exchange rates — just 30 rates relative to USD.
Both input fields update live as you type. Change the value on either side and the other recalculates immediately. Hit the swap button and the units flip — no need to re-enter the number. The formula used is shown below the fields so you always understand exactly what calculation is happening. The quick reference table below the main converter shows eight common output values simultaneously, so you can see how your input compares across the full range of units without clicking through each one individually.
The Data category includes both binary and decimal storage units. Kilobytes (KB) in the SI standard equal 1,000 bytes, while kibibytes (KiB) equal 1,024 bytes. This difference compounds at larger scales: a "gigabyte" as reported by your operating system is typically 1,073,741,824 bytes (GiB), while a hard drive manufacturer labels 1,000,000,000 bytes as a gigabyte (GB). Our converter includes both variants so you can accurately translate what your OS reports versus what a drive's advertised capacity means.
The Time category converts between milliseconds, seconds, minutes, hours, days, weeks, months, and years. The month value uses the average Gregorian month of 30.44 days, and the year uses 365.25 days to account for leap years. These are the standard values used in most scientific and engineering contexts. For calendar-exact date arithmetic (counting specific days between specific dates), use a dedicated date calculator instead.
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