Everything You Need to Ace Chemistry in One Big Fat Notebook by Jennifer Swanson

CALCULATING PERCENT ERROR
PERCENT ERROR is the difference between a measured
value and a known value expressed as a percentage. Percent
error shows how far the experimental value is from the
accepted value, when compared with the size of the actual
value. This is important because percent error tells you about
your measurement’s accuracy.
To calculate percent error, subtract the accepted value (A)
from the experimental value (E) (or vice versa, because you
will report the absolute value of this difference). Divide that
difference by A, the accepted value. Then multiply by 100.
Percent error = | E - A |
| A |
× 100
Accepted value is known to be true and
can be found in a standard reference.
Experimental value is the value
that you actually measured.
The percent error can be small or large. For example, if the
accepted value of the data is 35.67 g and the measured value
is 35.62 g, the percent error is 0.14%. However, if the accepted
value is 5 g and the measured value is 0.5 g, percent error
is 90%, which is much larger.
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