Map and Field Measurements
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.
- Enter the slope in degrees.
- Press the Tangent button.
- 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
US/UK World Magnetic Model - Epoch 2015.0 Main Field Declination (D)
(East Declination in Red, West in Blue; subtract from true compass reading)
