The latest articles on DEV Community by Ramesh Sah (@ramesh_sah_288c57352f1451). https://dev.to/ramesh_sah_288c57352f1451 https://media2.dev.to/dynamic/image/width=90,height=90,fit=cover,gravity=auto,format=auto/https:%2F%2Fdev-to-uploads.s3.amazonaws.com%2Fuploads%2Fuser%2Fprofile_image%2F3982289%2F6dcdda2d-7113-4130-830e-66268d882400.jpg https://dev.to/ramesh_sah_288c57352f1451 en Ramesh Sah Sat, 13 Jun 2026 07:02:01 +0000 https://dev.to/ramesh_sah_288c57352f1451/i-built-a-free-sleep-calculator-in-pure-htmlcssjs-no-frameworks-no-libraries-98-desktop-speed-37ka https://dev.to/ramesh_sah_288c57352f1451/i-built-a-free-sleep-calculator-in-pure-htmlcssjs-no-frameworks-no-libraries-98-desktop-speed-37ka <h1> Why I Built This: </h1> <p>I couldn't find a sleep calculator that was:</p> <ul> <li>Fast on mobile</li> <li>Free without ads</li> <li>Actually explained the science</li> <li>Didn't require signup</li> </ul> <p>So I built one from scratch in pure HTML/CSS/JS.</p> <h1> What is Sleep Calculator REM? </h1> <p><strong>sleepcalculatorrem.com</strong> is a free tool that <br> calculates your optimal wake-up and bedtime <br> windows based on 90-minute REM sleep cycles.</p> <p>Most people wake up groggy not because they <br> slept less — but because they woke up in the <br> MIDDLE of a sleep cycle.</p> <p>This tool solves that.</p> <h1> Features </h1> <h2> 3 Calculation Modes </h2> <ul> <li> <strong>Wake Up</strong> — enter bedtime → get best wake times</li> <li> <strong>Bedtime</strong> — enter wake time → get best bedtimes</li> <li> <strong>Sleep Now</strong> — calculates from current time instantly</li> </ul> <h3> Special Features </h3> <ul> <li>🧠 Visual REM cycle diagram</li> <li>👶 Age-based sleep recommendations</li> <li>📊 Sleep debt calculator (weekly tracker)</li> <li>⚙️ Custom cycle length (85–110 min)</li> <li>⏱️ Custom fall-asleep time setting</li> <li>🌙 Dark mode by default</li> <li>📋 One-tap copy alarm time button</li> </ul> <h2> Tech Stack </h2> webdev javascript opensource