The PPI Calculator is a free tool that helps you calculate ppi using the formula PPI = sqrt(width^2 + height^2) / diagonal. Enter your values above and press Calculate to get pixels per inch instantly, with a full step-by-step breakdown.
What is the PPI Calculator?
The ppi calculator is a free online tool that helps you calculate ppi quickly and accurately. It applies the standard formula PPI = sqrt(width^2 + height^2) / diagonal to the values you enter and, when you press Calculate, displays the result together with a clear, step-by-step explanation of how the answer was reached.
How to use the PPI Calculator
- Enter the screen width and height in pixels.
- Enter the diagonal in inches.
- See the PPI.
Formula used
The ppi calculator is based on this formula:
PPI = sqrt(width^2 + height^2) / diagonalEach term in the formula corresponds to one of the inputs explained below. The calculator performs the arithmetic for you and shows every step so you can check the working by hand if you wish.
Worked example
Suppose you enter 1920x1080, 15.6 in. The calculator works as follows:
| Inputs | 1920x1080, 15.6 in |
|---|---|
| Working | sqrt(1920^2+1080^2)/15.6 |
| Result | about 141 PPI |
Step-by-step calculation
- Apply the formula:
PPI = sqrt(width^2 + height^2) / diagonal - Substitute your values: sqrt(1920^2+1080^2)/15.6
- Read the result: about 141 PPI
Inputs explained
- Width (px) — the width used in the calculation.
- Height (px) — the height used in the calculation.
- Diagonal (inches) — the diagonal used in the calculation.
Understanding your result
- Pixels per inch — the calculated pixels per inch.
Benefits and practical uses
The ppi calculator saves time and removes the risk of manual errors when you need to calculate ppi. It is useful for students, professionals and anyone who wants a fast, dependable answer. Results update the moment you press Calculate, work on any device, and can be copied or shared in a single click — and because the maths runs in your browser, your figures stay completely private.
Tips for an accurate result
- Keep all related inputs in the same units.
- Use the worked example above to confirm you are entering values in the right places.
- Review the assumptions below so the result fits your situation.
- Press Reset to clear everything and try a different scenario.
Common mistakes to avoid
- Entering values in the wrong unit (mismatched units give wrong answers).
- Leaving a required field empty — the calculator will ask you to fill it in.
- Rounding inputs too early, which can slightly change the result.
Assumptions and limitations
- Square pixels.
Frequently asked questions
What is PPI?
Pixels per inch - a measure of screen sharpness.
How do I use the PPI Calculator?
Enter your values in the fields, then press the Calculate button to see the result. Use Reset to clear the form and start again. Nothing is calculated until you click Calculate.
What formula does the PPI Calculator use?
It uses the standard formula: PPI = sqrt(width^2 + height^2) / diagonal. The full step-by-step working is shown with every result so you can verify it.
What information do I need to use the ppi calculator?
You need: width, height, diagonal. Sensible example values are pre-filled so you can see how it works.
Is the PPI Calculator free to use?
Yes. Every DigiToolkit calculator is completely free, with no sign-up, no login and no usage limits.
Does the PPI Calculator work on mobile phones?
Yes. The calculator is mobile-first and works on phones, tablets and computers in any modern browser.
Do I need to install an app?
No. The ppi calculator runs directly in your web browser — there is nothing to download or install.
Is my data private when I use this calculator?
Yes. All calculations run inside your browser. The numbers you enter are never uploaded to a server or shared with anyone.
How accurate is the PPI Calculator?
It uses the generally accepted formula for ppi and computes to several decimal places. Results are accurate for the assumptions listed on this page.
Can I copy or share my result?
Yes. After calculating, use the Copy button to copy the result, or Share to copy the page link.
Why is nothing showing until I press Calculate?
By design, the calculator only computes when you press Calculate, so you can finish entering all your values first. Press Reset any time to clear everything.
What units does the PPI Calculator use?
It works with inches, px. Keep your inputs in consistent units for an accurate result.