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WGS84 vs NAD83 Difference in Feet
The difference between WGS84 and NAD83 is typically 0.5 to 2 meters (1.6 to 6.6 feet) in most of the contiguous United States, growing to over 2 meters in Alaska and Hawaii. While this sounds small, it is large enough to cause boundary disputes, engineering misalignment, and equipment positioning errors in professional applications.
Quick Answer: WGS84 and NAD83 differ by 0— meters in the US. They are close but not identical. Never assume they are the same in legal, construction, or survey-grade work.
What Is the Actual Shift?
Both WGS84 and NAD83 were originally defined to nearly coincide at the launch of the GPS system around 1987. Since then, plate tectonic movement has caused them to diverge. The shift depends on location:
| Region | Approximate Shift | Direction |
|---|---|---|
| Continental US (CONUS) | 0.9—.3 m (~3— ft) | Generally northward/eastward |
| Alaska | 1.5—.5 m (~5— ft) | Larger due to plate motion |
| Hawaii | ~1.5 m (~5 ft) | Pacific plate motion |
| Puerto Rico | ~1.0 m (~3.3 ft) | Caribbean plate |
Why Does This Matter for Professionals?
In everyday consumer GPS use, 1— meters is invisible. In professional contexts, it matters in several situations:
- Property boundary surveys: A 1-meter shift can place a corner on the wrong side of a fence line.
- Construction stakeout: Foundation placement accurate to centimeters requires datum consistency throughout the project.
- Pipeline and utility mapping: Assigning GPS-derived (WGS84) coordinates to NAD83 base maps displaces the asset.
- GIS data integration: Mixing WGS84 and NAD83 layers without transformation creates systematic offset across all features.
Common Mistake: Many GIS professionals assume WGS84 and NAD83 are interchangeable. The USGS and NOAA both explicitly state they are not equivalent for survey-grade work.
NAD83 Realizations (HARN, NSRS2007, 2011)
NAD83 itself has multiple realizations that differ slightly from each other:
- Original NAD83 (1986): The base realization
- HARN (1990s): High Accuracy Reference Network, improved by up to 1 meter in some states
- NSRS2007: National Spatial Reference System, centimeter-level accuracy relative to ITRF
- NAD83(2011): Current standard, aligned to ITRF2008
When comparing coordinates, always identify which realization of NAD83 was used. A coordinate in original NAD83 vs NAD83(2011) can differ by up to 1 meter.
How to Convert Between WGS84 and NAD83
Several transformation approaches exist:
- NADCON5 / NADCON: NOAA's official grid-based transformation for the US. Provides centimeter accuracy.
- Helmert 7-parameter transformation: Used in global software; less accurate than NADCON for US applications.
- Online tools: NOAA's NGS coordinate conversion tool handles WGS84↔NAD83 with NADCON.
Need to convert coordinates between WGS84 and other datums?
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Real Case: In the UK Great Britain Housing case, a developer overlaid raw WGS84 GPS data on OSGB36 maps, creating a 200m+ systematic offset across the entire site. The planning permission had to be voided and the project restarted. The same risk exists when mixing WGS84 and NAD83 in the US without explicit transformation.
—Read the Full Case Study
—Read the Full Case Study
WGS84 vs NAD83 vs NAD27
NAD27 is an older datum (North American Datum of 1927) still found on USGS topographic maps published before 1983. The shift between NAD27 and WGS84 is much larger —10 to 100+ meters depending on location. Never use GPS-derived WGS84 coordinates on a NAD27 map without transformation.
Professional Best Practices
- Always document the datum and realization of every coordinate dataset.
- Apply NADCON5 transformation when converting between WGS84 and NAD83 for survey-grade work.
- Never label coordinates simply as "GPS" without specifying WGS84 or the applicable realization.
- Verify datum consistency when integrating data from different agencies or time periods.
FAQ
Is WGS84 the same as NAD83?
No. They are very close (within 1— meters in most US locations) but not identical. Using them interchangeably in survey-grade, legal, or engineering work will introduce errors. Always apply a proper datum transformation.
Does Google Maps use WGS84 or NAD83?
Google Maps uses WGS84 as its underlying geodetic reference for coordinate display. The map tiles use Web Mercator (EPSG:3857) as the projection, but coordinates shown are WGS84 decimal degrees.
How many feet is 1 meter of datum shift?
1 meter equals approximately 3.281 feet. The typical 1—.3 meter WGS84 vs NAD83 difference in CONUS translates to roughly 3.3—.3 feet. In boundary disputes, this is sufficient to change which side of a property line a feature falls on.
What software handles WGS84 to NAD83 conversion correctly?
ArcGIS Pro, QGIS (with PROJ library), Global Mapper, and the NGS Online Coordinate Conversion tool all support NADCON5-based WGS84↔NAD83 transformations. Ensure you select the correct NAD83 realization (e.g., NAD83(2011)) matching your project datum.
Does the WGS84 vs NAD83 difference change over time?
Yes. The shift is increasing due to plate tectonic motion. North America moves approximately 2— cm per year relative to the ITRF reference frame, so the difference between these datums continues to grow annually.
See also: Geodetic Standards Comparison | Coordinate Error Cost Calculator | Professional Liability Hub
US State Plane (SPCS) Converters & Local Guides
Professional engineering and surveying transformations from state-specific conformal grids to GPS WGS84.
WGS84 vs NAD83 FAQs
What is the difference between NAD83 and WGS84 in meters? ▼
While originally identical in 1986, the North American tectonic plate has moved. Today, the difference between NAD83(2011) and modern realizations of WGS84 (like ITRF2014) is approximately 1 to 2 meters in the continental United States. This difference grows by about 1-2 cm per year.
Explore Technical DetailsDoes Google Maps use NAD83 or WGS84? ▼
Google Maps, standard GPS receivers, and most consumer mapping applications use WGS84. If you overlay WGS84 GPS data directly onto a professionally surveyed NAD83 CAD drawing without an explicit datum transformation, expect a constant 1-2 meter shift.
Explore Technical DetailsWhich datum should I use for FAA or aviation data? ▼
The International Civil Aviation Organization (ICAO) and the FAA explicitly require coordinates to be submitted in WGS84 format. Submitting airport coordinate data in NAD83 without proper transformation violates aviation standards and introduces safety liabilities.
Explore Technical DetailsProfessional Risk Notice
Using the wrong datum or applying coordinates without grid-to-ground correction can cause 1-400 metre positional errors —a leading cause of surveying negligence claims and contract disputes.
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The $50,000 Geodetic Drift Liability: NAD83 vs WGS84
Because the North American Plate moves ~2cm/year, NAD83(2011) and WGS84(G1762) currently diverge by over 2.2 meters. Using a "standard" GPS WGS84 coordinate for a high-precision NAD83 cadastral staking has triggered $50,000 Professional Liability claims for foundational rework and utility misplacement.
Risk Exposure Metric:
2.2-Meter Tectonic Drift & Epoch Accumulation
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