SAP Note 23771 - Quantity conversion with non-metric units

Symptom:

The quantity conversion between metric (meters, kilos, liters) and non-metric (yard, pound, gallon) units of measure is often only possible with big conversion errors.
When quantity units are being customized with factory that have more then five positions, the message "Field overflow ..." (BM398) or message V1384 is output.

Cause and prerequisites

In many applications, the conversion factors can only be represented as an integral decimal fraction with a maximum of 5 positions.

Solution
The following tables contain the conversion factors for some conversions from non-metric into metric units of measure which cause the least conversion error. The table specifies the conversion factor resulting in each case from the decimal fraction so that the conversion error can be judged.

Length:
Exact conversion | SAP conversion ----------------------------------------+-------------------------------
1 inch = 0,0254 Meter | 254/10000 = 0,0254
1 foot = 0,3048 Meter | 3048/10000 = 0,3048
1 yard = 0,9144 Meter | 9144/10000 = 0,9144
1 mile = 1,609344 Kilometer | 75438/46875 = 1,6093440000
------------------------------------------------------------------------
Surface:
Exact conversion | SAP conversion ----------------------------------------+-------------------------------
1 square inch = 6,4516 Square centimeter| 16129/2500 = 6,4516
1 square foot = 0,09290304 Square meters| 7099/76413 = 0,0929030401
1 square yard = 0,83612736 Square meters| 70325/84108 = 0,8361273601
------------------------------------------------------------------------
Volume:
Exact conversion | SAP conversion ----------------------------------------|-------------------------------
1 minimum = 0,06161152 Milliliter | 4009/65069 = 0,616115201
1 cubic inch = 16,387064 Milliliter | 48391/2953 = 16,3870640027
1 cubic foot = 28,316846592 Liter | 94465/3336 = 28,3168465228
1 cubic yard = 0,764554857984 Cubicmeter| 41393/54140 = 0,7645548578
1 dry pint = 0,5506105 Liter | 46493/84439 = 0,5506104999
1 liquid pint = 0,473176473 Liter | 47038/99409 = 0,4731764730
1 gallon = 3,785411784 Liter | 92065/24321 = 3,7854117841
------------------------------------------------------------------------
Weight:
Exact conversion | SAP conversion ----------------------------------------+-------------------------------
1 avdp. ounce = 28,349523125 Grams | 32687/1153 = 28,3495229835
1 avdp. pound = 0,45359237 Kilograms | 24445/53892 = 0,4535923699
1 short ton = 0,90718474 Tons | 24445/26946 = 0,9071847399
1 long ton = 1,016046909 Tons | 61861/60884 = 1,0160469089
------------------------------------------------------------------------

Further notes to avoid conversion errors:
- From several alternative units of measure always choose the smallest one as a base unit of measure for a material.
Example: If the units of measure grams, ounce, pound and kilos are useful for a material, gram should be chosen as a base unit of measure.
Since the inventory management is always carried out in base unit of measure and quantities are managed with exactly 3 places behind the decimal point, you can thus avoid conversion errors for small quantities moved.
- If conversion factors are maintained centrally in Customizing of the units of measure, the conversion is always maintained for the respective SI unit. If the unit of measure to be maintained has a dimension other than the SI unit (for example, 1 minimum << 1 cubic meter), you can only specify a very inaccurate decimal fraction.
Solution: Define non-metric units of measurem as without dimensions.
Advantage: You can define the conversion factors with maximum accuracy in the material master.
Disadvantage: You have to make sure organizationally that materials with the same units of measure also use the same conversion factors.
- Many conversion factors that are not listed in table can be determined by a corresponding multiplication since the relationship between two non-metric units of measure can often be represented with a decimal fraction (for example, 1 gallon = 4 liquid quarts).
- If you define special conversion factors, you have to consider that an exact conversion factor can often be represented simply by reducing the decimal fraction.
Example:
1 Unit1 = 0.10476 Unit2
100000 Unit1 = 10476 Unit2 (conversion factor is too large)
99999 Unit1 = 10476 Unit2 (big conversion error)
25000 Unit1 = 2619 Unit2 (reduced by 4, precise conversion factor)

Additional key words

imperial