Area Unit Converter

Overview

This converter puts fourteen area units on one table, using the square metre as the internal base so that metric, Chinese market and imperial figures can be read side by side. The Chinese mu is taken as 666.6667 m² and one hectare equals fifteen mu, which is how land contracts, subsidy sheets and property certificates are usually written; acres, square feet and square yards cover overseas listings and English drawings, while the square nautical mile serves sea-area work. The input accepts a plain number or an expression, and every unit is returned at once instead of being picked one by one. Both systems ship as fixed factor tables, so no value is guessed at run time. In practice the awkward conversions are the Chinese ones: a rural contract states mu and fen, a planning drawing states hectares, and an overseas listing states acres, so the same plot arrives in three vocabularies. Because mu is pegged to the metre through a fixed ratio rather than a surveyed local standard, the figure on the certificate and the figure in this table agree to the last decimal. Square nautical miles appear when fishery or sea-lease documents describe water area, where land units would be meaningless.

Features

• All fourteen area units are shown for a single input, with no repeated unit picking
• Expression input: 1/3, 2^2, (1+2)*3, or 1|2|4 for several targets; stray symbols are ignored
• Mu, fen and hectare line up directly: one hectare equals fifteen mu or 10,000 m²
• Acre, square foot, square inch and square yard cover English drawings and overseas listings
• Sort by value or by the reference order, with zero to eight decimals
• Batch mode accepts a unit per line such as "1 mu" or "50 ft2", exported as TXT or CSV

How to use

1. Type an area figure or an expression in the value box, for example 1234.5 or 100*2
2. Pick the source unit (square metre by default) and a target; leave the target empty to list all units
3. Read the headline result and the full fourteen-row table underneath
4. Use Swap to reverse the direction, or the sort dropdown to order rows by size
5. Paste several lines into the batch box, one record per line, then download TXT or export CSV

Notes

• Fourteen area units run from square metre through hectare, mu, fen and acre to square nautical mile, and every value is first normalised to square metres before being converted to the target.
• Market units follow the statutory definitions of 666.6667 m² per mu, fifteen mu per hectare and 66.6667 m² per fen, so cross-system error comes only from the decimal setting and matches cadastral practice.
• Expressions such as 1/3, 2*3 or 1+2 are evaluated directly and thousands separators are ignored; when source and target match, the input is echoed without a second rounding.
• Hectare, square kilometre, mu and fen cross-check each other, while Taiwan units such as jia and ping and obscure imperial ones like rood are not supported and need manual factors.
• Batch lines may carry a unit such as 100 m2, and TXT or CSV exports print numbers at the chosen decimal setting; the file holds bare numbers for direct spreadsheet use.
• The acre is identical in the United States and the United Kingdom: 4,046.8564 m², about 6.07 mu
• The square nautical mile uses 1 nmi = 1,852 m, giving 3,429,904 m² for sea areas and economic zones
• Decimals change display only; the internal maths runs in double precision, so repeated conversions do not accumulate rounding error