Download Time Calculator
How long will that download take? Enter a file size and your connection speed to get an exact ETA — for Steam games, big updates, 4K movies, or any upload. Use it as a game download calculator for your Steam library, queue many files in the batch tab, or reverse-solve the speed you need. Includes an honest MB-vs-MiB explainer.
Download ETA
Upload ETA
This upload time calculator uses your plan’s upload speed — usually much lower than download on cable/DSL — with the same honest ETA math.
Batch queue — total time for many files
What speed do I need?
MB vs MiB: the #1 source of download-time confusion
Internet speeds use SI decimal units: 1 Mbps = 1,000,000 bits per second — this is the networking standard your ISP, router, and speed tests use. File sizes are mixed: Windows and many game launchers report GiB (binary, 1 GiB = 1,073,741,824 bytes) while download pages usually mean GB (decimal, 1,000,000,000 bytes). A “100 GB” file measured in GiB takes about 7.37% longer. Pick the unit that matches your source in the size dropdown — both are supported honestly, never silently converted. As a gb to mb calculator: 1 GB = 1,000 MB (decimal) and 1 GiB = 1,024 MiB (binary).
Mbps to MB/s, instantly
Divide by 8: 100 Mbps ÷ 8 = 12.5 MB/s. Your 100 Mbps plan downloads at 12.5 MB/s — that is correct, not throttling. After ~5–10% TCP/IP overhead, expect roughly 11–12 MB/s in practice.
What “overhead” means
TCP/IP headers, retransmissions, and protocol chatter typically cost 5–10% of line speed. This is a labeled estimate, not a measurement of your connection — set it to 0% for the theoretical maximum.
Download time FAQs
What is a download time calculator?
A download time calculator estimates how long a file takes to download from your connection speed. Enter the file size and your speed, and it divides size by speed: for example, a 100 GB file on a 100 Mbps connection takes about 2 h 20 m 21 s (8,421 seconds) with 5% network overhead. This page also handles uploads, multi-file queues, and reverse lookups.
How long does it take to download 100 GB at 100 Mbps?
About 2 h 20 m 21 s — the full answer to the classic “how long to download 100gb” question. The math: 100 GB = 800,000 megabits; 800,000 ÷ 100 Mbps = 8,000 seconds raw (2 h 13 m 20 s), and adding a realistic 5% TCP/IP overhead brings it to 8421.1 seconds. Try the calculator above — change the overhead slider to see 0% vs 10%.
Why does my 100 Mbps internet only download at 12.5 MB/s?
That is correct, not throttling. Internet plans are sold in megabits per second (Mbps, small b) while downloads are measured in megabytes per second (MB/s, big B), and 1 byte = 8 bits: 100 ÷ 8 = 12.5 MB/s. After roughly 10% network overhead, a real speed around 11.25 MB/s on a 100 Mbps plan is completely normal.
Does MB vs MiB matter for download time?
Yes, about 7.37%. A 100 GB (SI decimal) file is 100,000,000,000 bytes, but 100 GiB (IEC binary) is 107,374,182,400 bytes. At 500 Mbps that is 26 m 40 s for 100 GB versus 28 m 38 s for 100 GiB. Operating systems and some game launchers report GiB while ISPs and most download pages use GB — pick the matching unit in the size dropdown.
How long does a 50 GB Steam game take to download?
About 23 m 24 s on a 300 Mbps connection with 5% overhead — the answer to “how long to download 50gb”. Steam shows your speed in MB/s: 300 Mbps ÷ 8 = 37.5 MB/s theoretical, around 35.6 MB/s after overhead. Use the game-size presets above (indie ~2 GB, AAA ~75 GB, patch ~15 GB are typical sample sizes — replace with your game’s actual size) or queue several games in the Batch tab. For any other Steam download time, just swap in your game’s size above.
How long does it take to upload a 1 GB video?
About 14 m 2 s on a 10 Mbps upload connection with 5% overhead. Upload speeds are usually much lower than download speeds on cable and DSL plans, so the same file that downloads in seconds can take many minutes to upload — use the Upload tab, which uses your plan’s upload speed.
What is the download time formula?
Time (seconds) = (file size in bytes × 8) ÷ (speed in bits per second × (1 − overhead)). Example: a 5 GB file at 50 Mbps with 5% overhead = (5,000,000,000 × 8) ÷ (50,000,000 × 0.95) ≈ 842 seconds, or about 14 m 2 s. The calculator above shows these steps for every result.
What speed do I need to download 25 GB in 30 minutes?
About 117.0 Mbps. The reverse lookup: 25 GB = 200,000 megabits; 200,000 ÷ 1,800 seconds = 111.1 Mbps raw, and dividing by (1 − 0.05) overhead gives 117.0 Mbps of line speed. Use the “Speed needed” tab for any size and deadline.
How much does network overhead slow down a download?
TCP/IP headers, retransmissions, and protocol chatter typically cost 5–10% of your line speed — this is an estimate, not a measured value for your connection. This calculator defaults to 5%; set it to 0% for the theoretical maximum or up to 30% for congested Wi-Fi. Even a gigabit (1,000 Mbps) line needs about 842 seconds for 100 GB after 5% overhead.
Is this the same as an internet speed test?
No. A speed test answers “how fast is my download right now” — it measures what your connection actually delivers. This calculator converts a known speed into a time estimate for a file. If your real downloads are much slower than the estimate, run a speed test — you may not be getting your plan’s advertised speed — then plug the measured speed in here for a realistic ETA.