True North vs Magnetic North
Explore declination context so map bearings and compass headings can be reconciled.
By Aryan Khan, Founder & Editor · Updated October 2026
For example, in New York your compass needle points about 13° west of true north, while in Los Angeles it points about 12° east of it — same country, opposite corrections, which is why this page exists.
How to use True North vs Magnetic North
Two norths, one needle — here is the angle between them:
True North vs Magnetic North explains the angle between the north your map uses and the north your compass finds — the declination. Learn which way your local needle leans, how much, and how to correct a bearing, so compass and map courses stop disagreeing by hundreds of metres.
- 1Set a location.
- 2Compare true bearing workflows with declination notes.
What people use True North vs Magnetic North for
1. Map and compass navigation
The classic use: convert map bearings to compass bearings (and back) with your local declination before the leg, not after the confusion. The Magnetic Declination tool gives the figure for your exact point.
2. Setting a compass's declination adjustment
Adjustable compasses take the correction once and then agree with the map all trip. This page explains what number you are dialling in and why it differs by region.
3. Solar and antenna alignment
Panels and dishes are aligned to true bearings; installers working from a compass reading without correction can miss by the full declination — over 15° in the Pacific Northwest.
4. Understanding old maps and surveys
Historic surveys ran on magnetic bearings of their day. Declination drift since then is part of why an 1890 bearing does not retrace cleanly with a modern needle.
Worked examples
Declination near New York is about 13°W. A map bearing of 90° (due east) needs a compass course of 90 + 13 = 103° — with west declination, add the angle to go from true to magnetic.
Walk a one-mile leg with a 13° error and you finish about 0.23 miles — roughly 1,200 feet — off to the side of your target (the offset is the leg length times the tangent of the error). Small angle, long walk, missed cabin.
Approximate declination, mid-2020s (WMM2025 era)
Rounded values for orientation — use the declination tool or NOAA for a current figure at your point.
| Place | Declination | Needle points |
|---|---|---|
| Seattle area | ≈15°E | East of true north |
| Los Angeles | ≈12°E | East of true north |
| Denver | ≈8°E | East of true north |
| Chicago | ≈3°W | West of true north |
| New York | ≈13°W | West of true north |
| London | ≈1°E | Nearly true north |
Values drift every year as the magnetic pole wanders — currently a few tenths of a degree per decade in most of the US, faster in places. Any printed figure ages; check the year on it.
How to interpret the result
The most common errors come from using a correct result to answer the wrong geographic question. Keep these points in mind for True North vs Magnetic North:
- Remember that elevation models see bare terrain: no buildings, no forest canopy. A line-of-sight 'clear' verdict can still be blocked by a wood, and a horizon distance assumes open ground — treat results as the terrain baseline, then add land cover from local knowledge.
- Include your height inputs explicitly (eye height, mast height, deck level) when sharing visibility results: the same hill answers differently for a child, an adult and a 10 m antenna, and unstated heights make numbers unreproducible.
Limits & appropriate use
Terrain intelligence carries one dominant limit: the model sees bare earth at ~90 m spacing with metres of vertical error, and is blind to canopies, walls and wires. Every downstream answer inherits it — profiles show terrain truth with noisy amplitude, line-of-sight verdicts are pending trees, horizons assume open ground, and solar radiation averages assume an unshaded panel. The second limit is temporal: climate letters and hardiness zones are thirty-year character, not this year's behaviour, and seismicity is a mood, not a hazard model. Each result here is printed with its recipe precisely so these boundaries travel with the number.
The value proposition is screening-grade truth at zero cost: orientation for sites, gardens, antennas, shoots and curiosity, with the upgrade points clearly marked. When money or safety attaches to the answer — tower siting, flood insurance, structural shading, avalanche terrain — the escalation is professional: licensed survey, certified shade studies, regulatory flood determinations and geological hazard services. A good free tool makes that ladder visible instead of pretending to be the top of it.
- Construction and tower siting → licensed topographic survey.
- Flood decisions → regulatory determinations (FEMA/FIRM in the US).
- Solar finance → certified shade and production studies.
Data & methodology
The shared bearing workspace reports true-north bearings; it does not retrieve magnetic declination or convert magnetic bearings.
For source details, licences and model limitations, see Data Sources and Methodology.
Key terms worth knowing
- Antipode
- The diametrically opposite point; latitude flips, longitude shifts 180°.
- Köppen class
- The letter-code climate system from temperature/precipitation thresholds.
Editorial guidance: MapBench explains the method and limitations so the tool can be used as a transparent reference, not as a black-box answer. For legal boundaries, safety-critical routing, surveying, engineering, regulated decisions or official statistics, verify the result with the responsible authority or a qualified professional.
Category: Earth Science. Results are intended for everyday analysis and planning unless a page explicitly states otherwise.
Method, assumptions & limits
- This tool’s method
- The shared bearing workspace reports true-north bearings; it does not retrieve magnetic declination or convert magnetic bearings.
- Before relying on the answer
- Check the location, height units and any model options shown by this calculator. A terrain lookup and a geometric Earth model answer different questions.
- What the result cannot establish
- Local terrain, atmospheric conditions and source resolution can matter more than numerical rounding. Do not use a planning result for safety-critical work.
Coverage: Worldwide. Search, basemap and external data requests may use third-party services; browser-based does not mean every operation is offline. Read the source and licence notes, calculation methodology and privacy policy. If a result looks inconsistent, report a correction with the inputs and mode used.
Frequently asked questions
Clear answers about the calculation, accuracy and appropriate use.
Changes yearly?
Magnetic field drifts — critical navigation should use current models.
Is this suitable for engineering or legal decisions?
Treat the result as planning or educational context unless the page explicitly says otherwise. Engineering, hazard and legal decisions should use authoritative specialist data.
Why can terrain data differ between sources?
Elevation and earth datasets vary in resolution, collection date and processing method. Small local features may not be represented equally.
Can I verify the data source?
Yes. MapBench documents major providers and methodology on the Data Sources and Methodology pages.
Which north does GPS use?
GPS positions are computed against true (geographic) north references — coordinates and map bearings are true. Only the compass needle answers to magnetic north, which is why phone compasses apply a model-based correction.
What is the agonic line?
The line of zero declination, where compass and true north agree. In the mid-2020s it runs through the US Midwest-Gulf region and drifts westward over time — Chicago sits just west of it, hence its small westerly value.
How fast does declination change?
Typically 0.05–0.15° per year in populated latitudes — Olympia, Washington's published figure changes about 0.12° per year westward. Over a decade on a stored map, that is a degree or more of silent error.
Does declination matter for short walks?
Barely — over a few hundred yards, even 15° is a modest offset and landmarks rescue you. It matters as legs lengthen and visibility shrinks: fog, forest, open water, night.
Why does my phone compass disagree with my handheld?
Phones apply a magnetic-model correction to display true north; a baseplate compass shows raw magnetic. Set the phone to magnetic in its settings, or adjust the baseplate, and the two agree.
What about grid north?
Map grids (UTM, national grids) tilt slightly against true north too — a third north, usually within a degree or two at mid-latitudes. Serious map work keeps all three straight; most walkers only ever meet two.
Did explorers really navigate without knowing this?
They learned it the empirical way — variation was charted from the 1700s (Halley's Atlantic chart of 1701 mapped it), and good navigators carried local values the way they carried tide tables.
Where is the magnetic north pole now?
In the Canadian Arctic, a few hundred kilometres from the geographic pole, drifting toward Siberia at roughly 30–50 km per year in recent decades (published estimates). That drift is the engine under every number on this page.
Related tools and resources
Your figure: the Magnetic Declination tool; bearings: the Bearing Calculator; visualise: the Compass Bearing Visualizer.
More free tools
Sources, methodology & editorial trust
- ✓ Browser-first processing where supported
- ✓ External sources are documented
- ✓ No account required for public tools
- ✓ Review data sources
Calculations are documented with their assumptions, limitations and source context rather than presented as unexplained answers.
Reviewed and maintained by Aryan Khan, Founder & Editor of MapBench.
Part of our bearing & midpoint hub
True North vs Magnetic North sits in the bearing & midpoint cluster, alongside 17 other tools that answer neighbouring questions with different methods or datasets.
You may also need
When this answer is only part of the job, these clusters cover the next step.
Read the guide behind this tool
How to Choose a Fair Meeting Point Between Two or More Places — A practical guide to geographic midpoints, travel-time fairness and choosing a meeting location that works in the real world rather than only on a straight-line map.