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FOV to Pixel Size Calculator

Calculate spatial resolution (pixel size) from FOV and Matrix.

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Inputs

mm
px

Your values stay on this device.

Results

Pixel Size
Pixel Area0.24

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Assumptions

  • The output reflects in-plane pixel spacing only and does not account for slice thickness or through-plane resolution.
  • Displayed detail also depends on reconstruction kernel, sampling, and modality-specific physics, not just pixel size.
  • This tool is useful for planning and explanation, but actual DICOM pixel spacing should come from the source data when available.

Sensitivity preview

Field of View -10%: Pixel Size 0.44 mm

Field of View Current: Pixel Size 0.49 mm

Field of View +10%: Pixel Size 0.54 mm

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About this Pixel Spacing

Spatial resolution is determined by the Field of View (FOV) and the Acquisition Matrix. Smaller pixels allow for finer detail but often reduce Signal-to-Noise Ratio (SNR). This calculator determines the physical dimension of one pixel.

Who this calculator is for

  • Radiology trainees, technologists, and physicists reviewing in-plane spatial resolution.
  • People who already know the field of view and matrix size from a protocol or dataset.
  • Learners comparing how CT and MRI resolution trade off against noise or signal.

When to use it

  • Use this calculator when translating a chosen FOV and matrix into a physical pixel size.
  • Use it to compare protocol options that change detail versus coverage.
  • Use it in teaching to connect acquisition parameters with in-plane measurement precision.

How to use this calculator

  1. Enter the Field of View (FOV) in millimeters.
  2. Enter the Matrix Size (e.g., 512 for CT, 256 for MRI).
  3. The result is the Pixel Size (mm).

Key assumptions

  • The output reflects in-plane pixel spacing only and does not account for slice thickness or through-plane resolution.
  • Displayed detail also depends on reconstruction kernel, sampling, and modality-specific physics, not just pixel size.
  • This tool is useful for planning and explanation, but actual DICOM pixel spacing should come from the source data when available.

Accuracy and testing

Review formula sources, default test cases, assumptions, unit handling, rounding rules, and changelog for this calculator.

View accuracy page

How this calculator works

Pixel Size = FOV / Matrix. For example, a 250mm FOV with a 512 matrix gives 250/512 = 0.488mm per pixel.

Inputs explained

FOV

The diameter of the scan area usually measured in mm or cm. (e.g., 250mm for a Head CT).

Matrix

The number of pixels across the image (Frequency or Phase encoding steps).

Understanding your results

Smaller pixel sizes mean higher resolution (better detail). However, in MRI, smaller pixels contain fewer protons, reducing signal (SNR).

Example scenarios

Head CT

FOV 250mm. Matrix 512. Pixel Size = 0.49 mm.

Body CT

FOV 400mm. Matrix 512. Pixel Size = 0.78 mm.

High Res MRI

FOV 160mm. Matrix 320. Pixel Size = 0.50 mm.

Key Features

  • Simple Division
  • Area Calculation
  • MM Precision

Tips & Best Practices

  • If you double the matrix while keeping FOV constant, you halve the pixel size and usually trade away signal or increase noise in practice.
  • Most CT scanners have a fixed matrix of 512x512.