*Scaling ratio (1:N)*or

*Map units per in./cm.*map properties can be used to specify the map scale.

*Scaling ratio (1:N)*, also called representative fraction, is a unit-less value that defines the relationship between distance on the map page to distance on the earth. A

*Scaling ratio (1:N)*of 1:10000 means that one inch on the map page represents 10000 inches on the land and one centimeter on the page represents 10000 centimeters on the land.

- Convert the desired ratio to a unit-less value, 1" : 8000 ft * 12"/ft = 1:48000
- Click the
*Map*frame in the**Contents**window. - Click the
**Scale**tab in the**Properties**window. - Enter the 48000 in the
*Scaling ratio (1:N)*field.

The *Map units per in./cm.* property is similar to the *Scaling ratio (1:N)*, but specifies units for both sides of the ratio 1:N. The 1 is one inch or one centimeter, depending on the page units. The N is *x* units, where the units depend on the map coordinate system.

Surfer 13 and earlier versions did not offer a scaling ratio option so the scale had to be assigned using the *Map Units per in./cm.* fields. In these cases, what to enter for the scale depends on the map X and Y units. You will need to calculate the scale, and then enter it for the map:

- Calculate the corresponding value for your map units (see below).
- Select
*Map*in the**Object Manager**. - In the
**Property Manager**, click the**Scale**tab. - Enter the calculated X or Y scale value. For example, if you wanted 1" = 8000' and your map coordinate system linear units is feet, you would enter 8000 to the right of
*Map units per in.*for your X or Y scale.

Whether the *Scaling ratio (1:N)* or *Map units per in./cm.* method is easier to use depends on the desired map scale, your page units, and your map target coordinate system linear units. Either method can always be used to arrive at the desired scale, but generally one will require less calculation.

**Example Calculations:**

These examples use inches for the page units. If your page units is set to *centimeters* the conversion factors are different, but the process is the same.

- If your map is in units of feet, then you would simply type in 8000. So Map units per in. = 8000.
- If your map is in units of meters, then you need to do some math. 8000 feet is 2438 meters. So 1"=8000' is the same as 1"=2438 meters, and you would enter Map units per in. = 2438.
- If your map is in units of lat/long, then you need to do some slightly more complicated math. You will need to convert 8000 feet to latitude and longitude.

1° of latitude is about 68.703 miles (362751 feet). So 8000 feet is about 0.02205° latitude. Insert this for the Y scale (Map units per in. = 0.02205 for the*Y Scale*).

1° of longitude is 69.172 miles * cos(latitude). So find the latitude of the center of your map and insert it in the equation to find how many miles 1° of longitude is for your map. So if your central latitude value is 39.5°:1° longitude = 69.172 mi * cos (39.5)

= 365228.16 feet * 0.77162

= 281819 feet8000' divided by 281819 '/° = 0.02839 map units (°)

Therefore, 8000 feet is 0.02839° longitude (at 39.5° latitude). First, clear the

*Proportional XY scaling*check box, and then insert this for the X scale (Map units per in. = 0.02839 for the*X Scale*).

*Updated November 13, 2018*

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