Download ETA Calculator
Enter file size and transfer speed to instantly calculate download time. Supports all units, batch mode, and a live progress simulator.
Add multiple files and a shared transfer speed to see total and individual download times.
Simulate a download in real time to visualise how long it feels at a given speed.
| Connection | Typical Speed | 1 GB download | 10 GB download |
|---|---|---|---|
| 56K modem | 0.056 Mbps | ~2 hr 0 min | ~20 hr |
| ADSL (basic) | 8 Mbps | ~16 min 40 sec | ~2 hr 47 min |
| 3G mobile | 3 Mbps | ~44 min | ~7 hr 24 min |
| 3G mobile (fast) | 8 Mbps | ~16 min 40 sec | ~2 hr 47 min |
| 4G LTE (avg) | 25 Mbps | ~5 min 20 sec | ~53 min 20 sec |
| 4G LTE (good) | 50 Mbps | ~2 min 40 sec | ~26 min 40 sec |
| Wi-Fi 4 (802.11n) | 40 Mbps | ~3 min 20 sec | ~33 min |
| Cable / VDSL2 | 100 Mbps | ~1 min 20 sec | ~13 min 20 sec |
| Wi-Fi 5 (802.11ac) | 200 Mbps | ~40 sec | ~6 min 40 sec |
| 5G Sub-6 (avg) | 200 Mbps | ~40 sec | ~6 min 40 sec |
| Wi-Fi 6 (802.11ax) | 400 Mbps | ~20 sec | ~3 min 20 sec |
| 5G Sub-6 (fast) | 500 Mbps | ~16 sec | ~2 min 40 sec |
| Gigabit Ethernet | 940 Mbps | ~8.5 sec | ~1 min 25 sec |
| Fibre (1 Gbps plan) | 1,000 Mbps | ~8 sec | ~1 min 20 sec |
| 5G mmWave | 2,000 Mbps | ~4 sec | ~40 sec |
| 10 Gigabit Ethernet | 10,000 Mbps | <1 sec | ~8 sec |
Speeds are typical real-world averages, not theoretical maxima. Assumes 1 GB = 1,000 MB = 8,000,000,000 bits (SI decimal).
How to Use the Download ETA Calculator
- Single mode: Enter the file size and select its unit (B, KB, MB, GB, TB). Enter the transfer speed and select its unit (Kbps, Mbps, Gbps, KB/s, MB/s, GB/s). The ETA updates instantly.
- Batch mode: Add multiple files with individual sizes, then set a shared speed. Click Calculate All to get per-file ETAs and a combined total time.
- Speed Test (Progress Simulator): Configure a file size and speed, then click Start Simulation to watch a real-time progress bar count down the transfer at your specified rate.
- Reference: View typical download times for popular connection types from 56K modem to 10 Gigabit Ethernet.
The Formula Behind Download ETA
The calculation is straightforward once all units are consistent. Convert the file size to bits, convert the transfer speed to bits per second, then divide:
Time (seconds) = File Size (bits) ÷ Transfer Speed (bits/second)
For example: a 1.5 GB file at 100 Mbps. First, convert 1.5 GB to bits: 1.5 × 1,000 × 1,000 × 1,000 × 8 = 12,000,000,000 bits. Then convert 100 Mbps to bps: 100 × 1,000 × 1,000 = 100,000,000 bps. Divide: 12,000,000,000 ÷ 100,000,000 = 120 seconds = 2 minutes 0 seconds. This tool uses SI decimal prefixes (1 GB = 10⁹ bytes), which matches how storage manufacturers and network engineers measure data rates.
Why Mbps Is Not the Same as MB/s
This is one of the most common sources of confusion in download time calculations. ISPs and network hardware manufacturers measure speed in megabits per second (Mbps). Download managers, operating system file transfer dialogs, and disk benchmarks measure throughput in megabytes per second (MB/s). Since 1 byte = 8 bits, you divide Mbps by 8 to get MB/s. A 100 Mbps connection transfers data at 12.5 MB/s — not 100 MB/s. When you enter a speed in this calculator, be sure to pick the correct unit from the dropdown to avoid an 8× error in your estimate.
Bytes vs. Bits: The Source of Most Errors
File sizes are almost always expressed in bytes (B, KB, MB, GB), while network speeds are almost always expressed in bits per second (Kbps, Mbps, Gbps). The conversion factor is 8: there are 8 bits in a byte. This tool handles the conversion automatically — just select the right units. The most frequent mistake when estimating download time manually is forgetting this factor and getting an estimate that is 8× too optimistic.
Real-World Speed vs. Advertised Speed
Your ISP's advertised speed is a theoretical maximum under ideal conditions with no other users on your node, minimal latency, and a server that can deliver at full speed. In practice, multiple factors reduce real throughput: Wi-Fi overhead typically reduces speed to 40–70% of the router's wireless spec. Network congestion during peak hours (evenings, weekends) can cut speeds by 30–60% on cable networks. Server throttling — many download servers cap per-connection speeds. TCP slow start means connections ramp up to full speed gradually, making short-file transfers feel slower proportionally. VPN overhead typically adds 10–20% to transfer time. For realistic estimates, use 70–80% of your plan speed for wired connections and 50–60% for Wi-Fi.
Batch Downloads and Sequential vs. Parallel Transfers
The Batch mode assumes you are downloading all files sequentially at a fixed shared speed. If you download files in parallel, each connection gets a fraction of your total bandwidth. For example, downloading four 1 GB files simultaneously at 100 Mbps means each file effectively gets ~25 Mbps, so all four finish in approximately the same time as downloading one 4 GB file sequentially. The batch total time is therefore the same whether files are sequential or parallel, assuming bandwidth is evenly shared. The difference is user experience: parallel downloads finish individual files faster but consume more CPU and memory.
Using the Progress Simulator
The progress simulator is designed to help you visualise transfer durations that are hard to estimate intuitively. A 500 MB file at 25 Mbps (typical 4G speed) takes 2 minutes 40 seconds — but watching the progress bar helps calibrate your mental model of how fast different connections are. The simulator updates every 200 milliseconds and accelerates internally for large simulations (files that would take hours in real life are compressed to a few seconds of animation) so you always see the full arc of a transfer in a reasonable amount of time. No actual data is transferred.