One of the main advantages of SI is that it eliminates confusion because there is a unique symbol for each unit irrespective of the language that is used.

You will also find it easier and in most cases faster to use the symbol instead of writing the name of each unit in full.

The basic rules for writing symbols

  • The symbols are always printed in upright type, irrespective of the typeface used in the text: m N s
  • Symbols are written in lower case (not capitals), except when the unit name is derived froma proper name: m for meter, s for second, but N for newton, A for ampere. The exeception is L for litre
  • Prefix symbols are printed in upright type without spacing between the prefix symbol and the unit symbol; kg for kilogram, km for kilometre
  • Symbols are never pluralized: 1 g, 45 g (not 45gs)
  • Names and symbols should not be mixed: N.M or newton metre, but not N metre or newton m
  • Never use a full stop after a symbol, except when it occurs at the end of a sentence
  • Always use a full space between the numeral and the symbol: 45 g (not 45g). Exception: When the first character of a symbol (for non-SI unit) is not a letter, no space is left: 32°C (not 32° C or 32 °C), 75° 12' 45" (not 75 ° 12 ' 45 ")
  • Symbols should be used in conjunction with numerals instead of writing out the unit names; when no numerals are involved unit names should be written out: Area of carpet is 16 m2 (not 16 square metres). Carpet is sold by square metre (not m2)
  • The product of two or more units in symbolic form may be indicated by a space or a dot: m s or m.s - metre second (not ms which would mean millisecond).