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PMS 437

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)

Recent map of magnetic declination for field navigation.

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NWCG Latest Announcements

WFSTAR 2026 Core Components Module Package and 2025 Fire Year in Review Now Available

Date:  March 23, 2026
Questions? 
Please contact: Joe Schindel

The 2026 Core Components Module Package for RT-130, Wildland Fire Safety Training Annual Refresher (WFSTAR) and the 2025 Fire Year in Review are now available on the NWCG website. The 2026 Core Components Module Package provides all content needed to deliver RT-130.

References:

2026 Core Components Module Package

2025 Fire Year in Review Module

NEW! S-490, Advanced Fire Behavior Calculations (Blended) Available Now

Date:  March 17, 2026
Questions? 
Please contact: Fire Behavior Subcommittee

NWCG is pleased to announce that the new S-490, Advanced Fire Behavior Calculations (Blended), 2026 course is now available.

This training includes performance-based activities that allow students to apply the knowledge and concepts required for the Fire Behavior Analyst (FBAN), Long Term Fire Analyst (LTAN), and Prescribed Fire Burn Boss Type 1 (RXB1) positions. It supports individuals working towards these incident qualifications.

This blended course begins with a self-paced online training (OLT) in the Wildland Fire Learning Portal (WFLP), followed by an in-person instructor-led training (ILT).

References:

S-490, Advanced Fire Calculations (Blended)

NWCG Fire Behavior Analyst (FBAN) Position Page

NWCG Long Term Fire Analyst (LTAN) Position Page

NWCG Prescribed Fire Burn Boss Type 1 (RXB1) Position Page

2024 Paul Gleason Award Winners Announced

Date:  March 13, 2026
Questions? 
Please contact: Leadership Committee

The NWCG Leadership Committee is proud to announce the recipients of the 2024 Paul Gleason "Lead By Example" awards. Award categories include Initiative and Innovation, Mentoring and Teamwork, Motivation and Vision, as well as a Lifetime Achievement Award.

Congratulations to the awardees:

  • Justin Baxter, National Unmanned Aerial System (UAS) Operations Specialist, with the U.S. Forest Service — Initiative and Innovation
  • Kelly Woods, Director of the Wildland Firefighting Lessons Learned Center — Mentoring and Teamwork
  • Doug Booster, Instructor, ProHealth Net, Inc. — Motivation and Vision
  • Pam McDonald, Writer-Editor for the National Interagency Fire Center — Lifetime Achievement Award

References:

Paul Gleason Lead By Example Award

Wildland Fire Leadership Development Program (WFLDP)

Leadership Committee

NEW! S-231, Engine Boss Course Available Now

Date:  March 6, 2026
Questions? 
Please contact: Incident Operations Subcommittee

NWCG is pleased to announce the new S-231, Engine Boss (Single Resource) course is now available on the Wildland Fire Learning Portal (WFLP). Developed through the Incident Performance and Training Modernization (IPTM) effort, this training supports individuals working towards Engine Boss, Single Resource (ENGB) incident qualifications. 

This is a performance-based instructor-led training (ILT) that focuses on the application of ENGB responsibilities during wildland fire operations, emphasizing readiness, information gathering, risk management, engine tactics, and Wildland Urban Interface (WUI) operations. Trainees apply these skills through scenario-based group work and an optional field day that reinforces hands-on engine operation tasks. 

References:

S-231, Engine Boss (Single Resource) (Instructor-led)

NWCG Engine Boss, Single Resource (ENGB) Position Page

Wildland Fire Learning Portal