FREE TOOL: Dial In the Perfect ND Exposure – Try Our Free Long Exposure (ND) Calculator

Adding a Neutral Density filter (ND) changes your exposure time – typically by several stops. This calculator takes your base shutter speed and ND strength and converts them into the correct long exposure time. So, now you can shoot those milky rivers and waterfalls with less trial-and-error.

How to use the calculator:

1. Set your base exposure: choose ISO, aperture, and a base shutter speed.
2. Select your ND strength in stops.
3. Read the calculated shutter duration.
4. Check the nearest standard shutter if you want a value that matches common 1/3-stop camera shutter speeds.
5. If the result is longer than 30s, use Bulb mode (and ideally a remote/intervalometer).
6. Use Copy result if you want to paste the full settings into notes or a shooting plan.

ND stops (quick explainer)

• An ND filter reduces the light reaching your sensor.
• Each +1 stop means half as much light, so you need double the shutter time to compensate (×2).
• This calculator only adjusts shutter speed. ISO and aperture are included for reference (and in the copied output).

For website owners: embed this on your site

Quick start

Paste this where you want the calculator to appear (WordPress “Custom HTML” block is fine):

<div class="diyp-longexposure-calculator"></div>
<link rel="stylesheet" href="https://www.diyphotography.net/diyptools/diyp-longexposure-calc.min.css">
<script src="https://www.diyphotography.net/diyptools/diyp-longexposure-calc.min.js" async defer></script>

You can add multiple calculators on a page—just add more <div class="diyp-longexposure-calculator"> blocks. All logic runs client-side.

Optional parameters (data-attributes)

Add these to the <div class="diyp-longexposure-calculator"> to set defaults or theme.

Attribute	Values	Default	What it does
data-title	Any text	DIYPhotography.net Long Exposure (ND) Calculator	Sets the visible header title.
data-nd	Integer stops (1–20)	10	Sets the starting ND strength.
data-shutter	Text (e.g. 1/125, 0.5, 2, 30, 2m, 1:30)	1/125	Sets the starting base shutter speed (the tool snaps to the nearest standard 1/3-stop shutter value).
data-aperture	Number (e.g. 8)	8	Sets the starting aperture (for copy text only; the ND calculation adjusts shutter only).
data-iso	Integer (e.g. 100)	100	Sets the starting ISO (for copy text only; the ND calculation adjusts shutter only).
data-theme	light | dark	light	Chooses the color theme.

Examples

Dark theme, ND 6 stops, base shutter 1/60:

<div class="diyp-longexposure-calculator" data-theme="dark" data-nd="6" data-shutter="1/60"></div>

Custom starting exposure (ISO 64, f/11, 1/125, ND 10):

<div class="diyp-longexposure-calculator" data-iso="64" data-aperture="11" data-shutter="1/125" data-nd="10"></div>

Custom title:

<div class="diyp-longexposure-calculator" data-title="Acme Lab — ND Shutter Helper"></div>

Notes for embedders

• Stop math: the tool multiplies shutter time by 2^stops (each stop doubles exposure time).
• Base shutter input: data-shutter accepts common formats (fractions like 1/125, decimals like 0.5, and time formats like 2m or 1:30) and is matched to the nearest standard 1/3-stop shutter value from 1/8000 to 30 seconds.
• 30s limit: if the calculated shutter exceeds 30 seconds, the tool shows Bulb for the nearest standard shutter and includes a note about using Bulb/intervalometer.
• Reference-only inputs: ISO and aperture are included to help you record a full exposure in the copied output; the calculator itself adjusts shutter speed only.
• Styling: CSS is namespaced under .diyp-longexposure-calculator to reduce conflicts.
• Multiple instances: the script auto-initialises any .diyp-longexposure-calculator it finds on page load.
• Performance: no network calls after the CSS/JS files load; everything runs in the browser.

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