National Wildfire Coordinating Group

Map and Field Measurements

Mapping Section

  1. Map Scale & Map Distance
  2. Slope Estimation
  3. Unit Conversions
  4. Average Latitude for Each State
  5. Declination

Map Scale & Map Distance

The map scale is printed in the map legend. It is given as a ratio of inches on the map corresponding to inches, feet, or miles on the ground. For example, a map scale indicating a ratio of 1: 24,000 (in/in), means that for every 1 inch on the map, 24,000 inches have been covered on the ground. Ground distances on maps are usually given in feet or miles.

Scale Rep. fraction Map (in/mi) Map (in/ch) Feet per map inch
1:253,440 253.44 0.25 0.0031 21120
1:126,720 126.72 0.50 0.0063 10560
1:63,360 63.36 1 0.0125 5280
1:62,500 62.50 1.01 0.0127 5188
1:31,680 31.68 2 0.025 2640
1:24,000 24 2.64 0.033 2000
1:21,120 21.12 3 0.0375 1760
1:15,840 15.84 4 0.05 1320
1:7,920 7.92 8 0.1 660

Firefighter Math Map Scale; Firefighter Math Spread/Map Distance

Slope Estimation

Slope (Degrees) Slope (Percent)
10° 17.6%
20° 36.4%
30° 57.7%
40° 83.9%
45° 100%
50° 119.2%
60° 173.2%
70° 274.7%
80° 567.1%
90° ∞

Standard LANDFIRE slope themes are represented in units of degrees (°). Many locally produced landscapes over the year’s stored slopes in percent (%). It is much easier to estimate slope in percent, estimating the elevation change and the horizontal distance and calculating the ratio. BehavePlus, and BEHAVE tools before that, default to slope input in percent.

Firefighter Math Slope Percent and Slope Angle

To convert from slope in degrees (°) to slope in percent (%), a scientific calculator is needed.

  1. Enter the slope in degrees.
  2. Press the Tangent button.
  3. Multiply the result by 100 to get slope in percent.

Unit Conversions

Online and downloadable apps are available from Apple (OSX & IOS), Google Play (Android), and MS Windows for making unit conversions for distance, temperature, area, volume, weight, time, energy and other items.

Metric Unit Multiply by English Unit Multiply by Metric Unit
Meters/min 3.28084 Ft/min 0.3048 Meters/min
Meters/min 2.982582 Ch/hr 0.33528 Meters/min
Meters/min 0.03728 Miles/hr 26.8224 Meters/min
Kg/m3 4.460897 Tons/ac 0.22417 Kg/m3
Kg/m3 0.062 lb/ft3 16.129 Kg/m3
Tonnes/ha 0.44609 Tons/ac 2.2417 Tonnes/ha
Kw/m 0.28909 BTU/ft/sec 3.4592 Kw/m
Meters 0.049709 Chains 20.117 Meters
Meters 0.3048 Feet 3.28084 Meters
Millimeters 0.0393701 Inches 25.4 Millimeters
kilometers 0.62137 miles 1.6093 kilometers
hectares 2.4711 acres 0.40469 hectares

Firefighter Math Conversions reference provides several tables and conversion factors for the user.

Average Latitude for Each State

State Average Latitude
Alabama 33
Alaska 65
Arizona 35
Arkansas 35
California 38
Colorado 39
Connecticut 41
Delaware 39
Florida 28
Georgia 33
Hawaii 21
Idaho 45
Illinois 40
Indiana 40
Iowa 42
Kansas 39
Kentucky 37
Louisiana 31
Maine 45
Maryland 39
Massachusetts 42
Michigan 43
Minnesota 46
Mississippi 32
Missouri 39
Montana 47
Nebraska 41
Nevada 39
New Hampshire 44
New Jersey 40
New Mexico 34
New York 43
North Carolina 35
North Dakota 47
Ohio 40
Oklahoma 35
Oregon 44
Pennsylvania 41
Rhode Island 41
South Carolina 34
South Dakota 44
Tennessee 36
Texas 32
Utah 39
Vermont 44
Virginia 37
Washington 47
West Virginia 38
Wisconsin 44
Wyoming 43

Declination

Global Reference

Calculator

US/UK World Magnetic Model - Epoch 2015.0 Main Field Declination (D)

(East Declination in Red, West in Blue; subtract from true compass reading)

recent map of magnetic declination for field navigation.

 

 

PRINT FBFRG Map and Field Measurements
Page Last Modified / Reviewed: 
2021-07-07