Unit converters

Exact, wherever the units are exactly defined — and most are. One inch is defined as exactly 25.4 mm, one pound as exactly 0.45359237 kg, one mile as exactly 1,609.344 m. The converters use those defined factors directly, so the only rounding you see is in the displayed decimal places.

No — the Currency Converter uses approximate reference rates meant for planning: sizing a trip budget, comparing a foreign price tag, sanity-checking an invoice. Your bank, card issuer, or exchange service applies its own rate plus fees at transaction time, so always check with them before moving real money.

Both conventions exist. Decimal (SI) units define 1 kB = 1,000 bytes, which is how drive manufacturers label capacity. Binary units define 1 KB = 1,024 bytes, which is how most operating systems report file sizes — and why a "1 TB" drive shows up as about 931 GB. The Data Storage Converter uses the binary (1,024) convention and says so on the page.

Standard Roman notation has no symbol larger than M (1,000), and convention allows at most three repeats of a symbol — so 3,999 (MMMCMXCIX) is the ceiling. Larger numbers historically used a vinculum (an overline multiplying a numeral by 1,000), which is outside standard modern usage; the converter covers the standard 1–3,999 range.