---
title: "Sparrow Criterion calculator — AperiOptic"
description: "Resolution limit where two PSFs merge (no central dip). Free online optics calculator, with the formula and code snippets."
url: "https://aperioptic.com/calculators/sparrow-criterion"
---

# Sparrow Criterion calculator

Resolution limit where two PSFs merge (no central dip).

Category: [Imaging](https://aperioptic.com/calculators)

Formula: `d = 0.4736·λ/NA`

## Inputs

| Input | Parameter | Unit | Default |
| --- | --- | --- | --- |
| Wavelength | `lam` | nm | 550 |
| NA | `NA` |  | 0.5 |

## Result with the default inputs

- Sparrow d: 520.9354 nm

Open it with your own values: put each input in the address as a parameter, for example [`/calculators/sparrow-criterion?lam=550`](https://aperioptic.com/calculators/sparrow-criterion?lam=550). A unit other than the listed one goes in `<parameter>_unit`.

Read more: [Wikipedia: Angular resolution, Sparrow limit](https://en.wikipedia.org/wiki/Angular_resolution#Sparrow_limit)

[All optics calculators](https://aperioptic.com/calculators)

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The interactive page: https://aperioptic.com/calculators/sparrow-criterion (AperiOptic runs in the browser; free, no account). Every page of the site as Markdown: https://aperioptic.com/llms.txt