This is the capacity math, not a setup guide: enter your CPU, your bitrate, and your client mix, and get an exact simultaneous-stream ceiling for your specific NAS or server, with the bottleneck named. If you already have Plex, Jellyfin, or Emby running and want setup or comparison help, that lives in the guides linked here instead.
Most buffering and stalled-stream problems trace back to one of three numbers: whether your clients can direct play your files, whether your CPU has enough transcoding headroom, or whether your upload speed can keep up. This calculator runs that math against your actual hardware and content instead of a rule of thumb. Enter your CPU, your library's resolution and bitrate, and how many people will be watching at once, and it returns a realistic, conservative stream count, tells you which of the three limits hits first, and what to change if the answer is not enough.
Stream capacity depends on whether clients direct play or transcode. Direct play requires almost no server CPU, the client device does the decoding. Transcoding requires the server to re-encode video in real time, which is CPU-intensive.
For transcoded streams, we use CPU Passmark scores as the baseline: approximately 2,000 Passmark per 1080p H.264 software transcode, 2,500 per 1080p H.265, and 12,000-17,000+ for 4K content. Hardware transcoding (Intel QuickSync, Nvidia NVENC) dramatically reduces CPU load, a Celeron with QuickSync can handle 3-4 simultaneous 1080p transcodes that would overwhelm it in software mode. We then verify that network bandwidth (total bitrate vs available) and storage throughput (read speed vs drive performance) aren't the bottleneck.
Our estimates are conservative. Real-world performance varies with file complexity, codec profiles, subtitle handling, and background tasks. For the "Mix of both" client type, CPU utilisation is estimated assuming 50% of streams require transcoding, if your actual mix leans more toward direct play, your real CPU load will be lower. These calculations apply equally to Plex, Jellyfin, and Emby, the underlying hardware requirements are the same across all three platforms. See our best NAS for Plex guide for specific model recommendations.
Prices are indicative. Hardware prices on this page are indicative AU street prices and are not automatically updated, so they may be out of date. Re-check current pricing before budgeting.
What's the difference between direct play and transcoding?
Direct play means your client device (TV, phone, streaming box) can natively decode the video file, the server just sends the file as-is, using almost no CPU. Transcoding means the server converts the video in real time to a format the client can understand. This is CPU-intensive and is the main reason NAS devices struggle with multiple streams. The single biggest thing you can do to improve Plex performance is ensure your clients can direct play your files.
How do I know if my NAS can handle Plex?
Check two things: the CPU's Passmark score and whether it supports hardware transcoding (Intel QuickSync). For direct play only, almost any NAS works, even a Synology J-series. For transcoding, you need at least a Celeron J4125 (Passmark ~3,000) with QuickSync enabled for 2-3 simultaneous 1080p streams. For 4K transcoding, you need a desktop-class CPU (i3 or better). See our best NAS for Plex guide for specific model picks.
What is Intel QuickSync and why does it matter?
QuickSync is Intel's built-in hardware video encoder/decoder, present in most Intel CPUs from roughly 2015 onward. It offloads video transcoding from CPU cores to dedicated silicon, dramatically reducing CPU load. A Celeron J4125 with QuickSync can handle 3-4 simultaneous 1080p transcodes, without QuickSync, the same chip manages maybe 1 before stuttering. In Plex, you need a Plex Pass subscription to enable hardware transcoding. In Jellyfin, it's free.
Can I run Plex on a Synology or QNAP NAS?
Yes, both Synology and QNAP offer Plex as an installable package, and Jellyfin/Emby are available via Docker on most models. The critical factor is which CPU your NAS has. Synology's value J-series (Realtek ARM chips) can only handle direct play, no transcoding. The Plus-series models (Celeron/Pentium chips with QuickSync) handle 2-4 transcoded 1080p streams comfortably. Check your specific model's CPU before buying for media server use.
Is 4K streaming on a NAS realistic?
For direct play, yes: 4K direct play works on any NAS with a gigabit or better network connection and clients that support the codec. The files are large (40-80 Mbps for remuxes) but a single HDD handles that throughput easily. For transcoding, 4K is still brutal. Software transcoding a single 4K stream requires 12,000+ Passmark, more than most NAS CPUs offer. The practical advice: keep 4K for local direct play on capable devices, and set remote streams to transcode down to 1080p.
How does remote streaming work with Australian NBN?
Remote streaming (outside your home) depends on your NBN upload speed, not download. Most common plans: 50/20 gives 20 Mbps upload, 100/20 gives 20 Mbps, 100/40 gives 40 Mbps, 250/25 gives 25 Mbps. A single 1080p stream at 8 Mbps uses 40% of a 20 Mbps upload, two remote streams nearly saturates it. Set remote stream quality to 720p 4Mbps or 1080p 8Mbps in Plex to stay within budget. Also note: if you're behind CGNAT (common on NBN fixed wireless), you'll need a workaround like Tailscale, see our NAS remote access guide.
Does this tool apply to Jellyfin and Emby as well as Plex?
Yes. The underlying hardware requirements: CPU power for transcoding, network bandwidth, storage throughput, are identical across all three platforms. The main software difference: Plex requires a Plex Pass subscription (check plex.tv for current AUD pricing, lifetime pricing rose significantly from 1 July 2026) to enable hardware transcoding, while Jellyfin offers it free. Emby requires an Emby Premiere licence.
Why is my Plex server buffering even though it "should" work?
The most common causes, in order: (1) Unexpected transcoding, your client can't direct play the file (check the Plex dashboard during playback). (2) WiFi congestion with multiple streams. (3) Subtitle burn-in, image-based subtitles (PGS/VOBSUB) force transcoding even when the video codec is compatible. (4) HDR tone mapping, if your client doesn't support HDR, the server tone-maps in real time. (5) Background tasks, library scans and thumbnail generation compete for CPU during playback.
Recommended NAS units for Plex in Australia, balancing transcoding CPU performance and AU retail availability. Prices follow the NTKIT market-price tracker; a model with no current publishable price shows "Check current retailer prices" instead of a stale figure.
| NAS | CPU | 1080p transcode streams | AU market price |
|---|---|---|---|
| Synology DS425+ | Intel Celeron J4125 | 1 (software) / up to 4 (hardware, QuickSync) | $899 |
| Synology DS925+ | AMD Ryzen V1500B | 2 (software) | $1,099 |
| QNAP TS-464 | Intel Celeron N5095 | 3-5 (hardware transcode) | $1,129 |
| QNAP TS-464C | Intel Celeron N5095 | 3-5 (hardware transcode) | Check current retailer prices |
| Synology DS1823xs+ | AMD Ryzen V1780B | 3 (software) | $3,246 |
| UGREEN DXP4800 Plus | Intel Pentium Gold 8505 | several (hardware, QuickSync) | Not currently listed by an AU retailer |
Plex remote streaming (outside your home) uses your NBN upload speed, not download. Upload speed in Mbps is roughly 8x the equivalent MB/s figure, don't confuse the two when sizing this against an 8 Mbps 1080p remote stream:
Most AU homes on NBN100 can support 1-2 remote Plex streams comfortably. For family use with multiple remote devices, NBN250 or higher is recommended. Use our Transfer Speed Estimator to calculate specific stream counts at your plan speed.
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