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Calcimator

GPS Accuracy Estimator

Estimate GPS/GNSS positional accuracy from satellite geometry (GDOP/PDOP), correction method, and environmental factors.

Inputs

ft
°

Results

Horizontal Accuracy (95%)

6.72 m

≈ 4 adult heights

Vertical Accuracy (95%)

8.16 m

≈ 5 adult heights

Horizontal (feet)22.05 ft
Vertical (feet)26.77 ft
3D Position Accuracy10.57 m
HDOP1.12
VDOP1.36
Geometry QualityExcellent
Correction MethodStandalone GPS
Suitable ForRecreation / navigation
How to Use This Calculator
  1. Enter the GDOP Value (geometric dilution of precision) and the Receiver UERE (user equivalent range error) for your equipment.
  2. Enter the number of Satellites Tracked and select the Correction Method — Standalone GPS, SBAS/WAAS, Differential GPS, or RTK.
  3. Set the Elevation Mask angle and choose the Multipath Environment — Low, Moderate, or Heavy — to reflect your survey site.
  4. Review the Horizontal Accuracy (95%) and Vertical Accuracy (95%) outputs, shown in meters and feet.
  5. Check the Geometry Quality and Suitable For outputs to confirm the correction method meets your required precision.

How the result changes with GDOP Value

GDOP ValueHorizontal Accuracy (95%)Vertical Accuracy (95%)
3.4511.59 m14.08 m
1136.96 m44.88 m
2067.2 m81.6 m
2790.72 m110.16 m

What each input means

GDOP Value
Geometric Dilution of Precision. Lower = better geometry. Ideal < 2, good < 5.
Receiver UERE
User Equivalent Range Error — base accuracy of the receiver before DOP. Typical GPS: 3-5 m.
Satellites Tracked
Number of satellites visible. Minimum 4 for 3D fix. More satellites generally means better geometry.
Correction Method
Type of differential correction applied. RTK provides centimeter-level accuracy.
Elevation Mask
Minimum satellite elevation angle. Higher masks reduce multipath but may reduce satellite count.
Multipath Environment
Level of signal reflection from nearby surfaces (buildings, trees, terrain).

How this is calculated

Worked example, using the default values

  1. Identify Input Parameters
    4 parameters
    GDOP Value = 2, Receiver UERE = 3, Satellites Tracked = 8, Correction Method = 1 = 6 input(s) provided
  2. Calculate Horizontal Accuracy
    Horizontal Accuracy
    6.72 = 6.72
  3. Calculate Vertical Accuracy
    Vertical Accuracy
    8.16 = 8.16
  4. Calculate Horizontal
    Horizontal
    22.048 = 22.048
  5. Calculate Vertical
    Vertical
    26.773 = 26.773

Engine last updated . Checked against 3 independently-derived tests — how we verify calculators.

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