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Mapping: Map and Field Measurements

  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.

ScaleRep. fractionMap (in/mi)Map (in/ch)Feet per map inch
1:253,440253.440.250.003121120
1:126,720126.720.500.006310560
1:63,36063.3610.01255280
1:62,50062.501.010.01275188
1:31,68031.6820.0252640
1:24,000242.640.0332000
1:21,12021.1230.03751760
1:15,84015.8440.051320
1:7,9207.9280.1660

Firefighter Math Map Scale; Firefighter Math Spread/Map Distance

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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.

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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 UnitMultiply byEnglish UnitMultiply byMetric Unit
Meters/min3.28084Ft/min0.3048Meters/min
Meters/min2.982582Ch/hr0.33528Meters/min
Meters/min0.03728Miles/hr26.8224Meters/min
Kg/m34.460897Tons/ac0.22417Kg/m3
Kg/m30.062lb/ft316.129Kg/m3
Tonnes/ha0.44609Tons/ac2.2417Tonnes/ha
Kw/m0.28909BTU/ft/sec3.4592Kw/m
Meters0.049709Chains20.117Meters
Meters0.3048Feet3.28084Meters
Millimeters0.0393701Inches25.4Millimeters
kilometers0.62137miles1.6093kilometers
hectares2.4711acres0.40469hectares

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

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Average Latitude for Each State

StateAverage Latitude
Alabama33
Alaska65
Arizona35
Arkansas35
California38
Colorado39
Connecticut41
Delaware39
Florida28
Georgia33
Hawaii21
Idaho45
Illinois40
Indiana40
Iowa42
Kansas39
Kentucky37
Louisiana31
Maine45
Maryland39
Massachusetts42
Michigan43
Minnesota46
Mississippi32
Missouri39
Montana47
Nebraska41
Nevada39
New Hampshire44
New Jersey40
New Mexico34
New York43
North Carolina35
North Dakota47
Ohio40
Oklahoma35
Oregon44
Pennsylvania41
Rhode Island41
South Carolina34
South Dakota44
Tennessee36
Texas32
Utah39
Vermont44
Virginia37
Washington47
West Virginia38
Wisconsin44
Wyoming43

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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)

Image
Recent map of magnetic declination for field navigation.

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NWCG Latest Announcements

National Wildland Firefighter Day

Date: July 2, 2025
Questions?  Please contact:
National Interagency Fire Center

The National Wildfire Coordinating Group (NWCG) recognizes July 2, 2025, as National Wildland Firefighter Day (NWFFD). Established in 2022, NWFFD honors the dedication of wildland firefighters and support personnel. This day falls within the 2025 Week of Remembrance (June 30 - July 6), providing an opportunity to renew our commitment to wildland firefighter safety while remembering those who have fallen in the line of duty.

NWCG provides leadership to enable interoperable wildland fire operations among federal, state, local, Tribal, and territorial partners. NWCG standards and training establish common practices to contribute to safe, effective, and coordinated interagency wildland fire operations nationwide.

References:

Week of Remembrance

National Wildland Firefighter Day

2025 Week of Remembrance

Date: June 27, 2025
Questions?  Please contact:
6 Minutes for Safety Subcommittee

As we approach the 2025 Week of Remembrance (WOR), June 30–July 6, we dedicate this time to reflect on the past incidents from 2015 and honor the fallen through learning. Since its inception in 2014, WOR has honored wildland firefighters who made the ultimate sacrifice while encouraging critical discussions that reinforce lessons learned.

Throughout the week, we encourage thoughtful and generative conversations—whether in briefing rooms or at tailgates—that promote a culture of continuous learning and safety.

References:

2025 Week of Remembrance: Letter to Leadership

Wildland Fire Lessons Learned Center

ETC Equipment Bulletin: 25-003 Flame-Resistant Shirt Survey

Date: June 12, 2025
Questions?  Please contact:
Equipment Technology Committee

The U.S. Forest Service National Technology and Development Program (NTDP) is seeking input on the Forest Service-designed flame-resistant (FR) shirt, currently available through the National Interagency Support Cache system and FedMall.

NTDP is conducting a product review to improve future FR shirt designs. As part of this effort, a short survey is now open for federal employees who have worn any of three recent FR shirt models. Feedback will guide design improvements to better meet the needs of wildland firefighters.

To comply with the Paperwork Reduction Act, responses are limited to federal employees. The survey is open through September 12, 2025. 

References:

NWCG Alerts

ETC Equipment Bulletin: 25-003

NEW! S-130, Firefighter Training (Blended) Now Available

Date: June 10, 2025
If you have questions, please visit our FAQ page. 
If your question is not answered there, you can 
submit your question using our Contact Us form. 
 

The S-130, Firefighter Training (Blended), equips new wildland firefighters with essential skills through a mix of online learning and hands-on training. The course features a required online component and an instructor-led exercise, reinforcing online concepts with practical performance-based training.

The course builds competencies in wildland fire operations, safety, and equipment use, applicable across various operational environments. Both the online component and instructor-led field exercise must be completed to receive a certificate of completion. Students are required to finish the prerequisite S-190, Introduction to Wildland Fire Behavior, before enrolling in S-130, Firefighter Training (Blended).

References:

S-130, Firefighter Training (Blended)

S-190, Introduction to Wildland Fire Behavior

Wildland Fire Learning Portal