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hmcal is a lightweight, client-side duration calculator designed for fast time arithmetic. It handles mixed-unit expression inputs like 4h20m*7+30m, 1:20:00+2:15, or (20m+30m)*2 in real time, converting everything instantly into D HH:MM:SS, minutes, and seconds. 100% local, privacy-focused, zero tracking, and no server requests.
Hi Product Hunt! 👋
I’m the creator of hmcal (Hour-Minute Calculator).
The Backstory:
It all started with a friendly bet with a friend — we each had to hit 49 hours of sleep per week, with a twist: extra time spent learning, working out, building side projects, or pursuing personal interests outside of work could offset missing sleep. But for every minute we fell short, the fine was $1/min! (Spoiler: I ended up paying quite a bit, so calculating exact durations became very high-stakes!)
Trying to sum up sleep logs and offset hours across multiple activities in mixed formats (like adding 4h20m to 1:20:00) using standard calculators or spreadsheets every week was a total pain. So, I built hmcal to solve our very real (and expensive) problem.
The Solution:
hmcal is an intuitive, instant web calculator that parses complex duration expressions directly in your browser.
Highlights:
• Flexible Inputs: Supports mixed units (d/h/m/s), colon format (hh:mm:ss), double dots (hh..mm), pure numbers, and nested parentheses.
• Instant Real-Time Normalization: Evaluates inputs live with standard "D HH:MM:SS", total minutes, and total seconds breakdowns.
• 100% Local & Private: Built with Astro for absolute control over HTML output, zero server calls, zero tracking, and 100% client-side execution.
🔗 Try it here: https://brucencnp.com/tools/hmcal/
I’d love to get your feedback on the parser logic, edge-case syntax, or UI refinements!
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About hmcal on Product Hunt
“A fast, 100% local time & duration calculator”
hmcal was submitted on Product Hunt and earned 0 upvotes and 1 comments, placing #37 on the daily leaderboard. hmcal is a lightweight, client-side duration calculator designed for fast time arithmetic. It handles mixed-unit expression inputs like 4h20m*7+30m, 1:20:00+2:15, or (20m+30m)*2 in real time, converting everything instantly into D HH:MM:SS, minutes, and seconds. 100% local, privacy-focused, zero tracking, and no server requests.
hmcal was featured in Web App (123.7k followers), Productivity (660.2k followers) and User Experience (368.1k followers) on Product Hunt. Together, these topics include over 229.7k products, making this a competitive space to launch in.
Who hunted hmcal?
hmcal was hunted by Bruce NCNP. A “hunter” on Product Hunt is the community member who submits a product to the platform — uploading the images, the link, and tagging the makers behind it. Hunters typically write the first comment explaining why a product is worth attention, and their followers are notified the moment they post. Around 79% of featured launches on Product Hunt are self-hunted by their makers, but a well-known hunter still acts as a signal of quality to the rest of the community. See the full all-time top hunters leaderboard to discover who is shaping the Product Hunt ecosystem.
Want to see how hmcal stacked up against nearby launches in real time? Check out the live launch dashboard for upvote speed charts, proximity comparisons, and more analytics.
Bruce NCNP