DownClock

Ever wondered exactly how long a 4K video will take to upload, or whether your new ISP plan is actually faster? DownClock gives you an instant, accurate answer.

Enter a file size (KB to TB, binary or SI), pick your connection speed from common presets or type your own, and watch the result roll in — days, hours, minutes, seconds.

Built for developers, IT admins, content creators, and anyone comparing ISP plans. No ads. No accounts. No nonsense.

FEATURES

• File sizes from KB to TB — binary (KiB/GiB) and SI units
• Speed presets: 1 Mbps to 10 Gbps
• Compare two ISP providers side by side
• Calculation history
• Protocol overhead slider (TCP/IP + HTTP)
• ISP efficiency slider (advertised vs. actual speed)
• Animated rolling-digit result display
• Light, dark, or system appearance
• iPhone and iPad — portrait optimized
• Zero network requests. Completely private.