CONVERTING MILLIBARS TO INCHES OF MERCURY
 
METEOROLOGIST JEFF HABY
1013.25 millibars is equal to 29.92 inches of mercury. These value are the average sea level
pressure in each unit. To convert between the two units cross multiplication algebra can
be used.
This will involve setting the two values as a ratio to each other and then putting the
known value on the other side of the equation. The unknown will also be on the
other side of the equation and either in the numerator or denominator. If mb is on
top on one side of the equation then it must be on top on the other side of the
equation. The same works for inches of mercury.
Suppose we want to know what 1034 mb is in inches of mercury. Here is how the unknown x is found.
1013.25 mb / 29.92 inches of mercury = 1034 mb / x
Notice on the left side of the equation the two knowns are in a ratio of each other. Since mb
is the known value it is put in the numerator on the other side of the equation since 1013.25 mb
is in the numerator on the other side of the equation.
Next, cross multiplication is done. x is multiplied by 1013.25 while 29.92 is multiplied by
1034. This yields:
x * 1013.25 mb = 29.92 inches of mercury * 1034 mb
Next, solve for x. The units cancel to inches of mercury
x = (29.92 * 1034) / 1013.25 = 30.53 inches of mercury


