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NAS File Transfer Speed Estimator

This NAS file transfer speed estimator calculates how long a file transfer will actually take based on your connection type, NAS drive speed, and file size. Covers LAN, 10GbE, and WAN (remote access) scenarios with Australian NBN upload context.

Upgrading to 10GbE doesn't guarantee 10GbE speeds. Your actual file transfer speed is limited by the slowest link in the chain, your network, your computer's drive, your NAS storage, or the type of files you're moving.

This estimator models the bottleneck. Select your network, drives, NAS storage, and workload type to see a realistic speed range and find out what's actually limiting your transfers.

Your Setup

Transfer Direction

Network Speed

Jumbo Frames

Jumbo Frames (9000 MTU)

Client Computer Drive

NAS Storage Type

RAID Type

Number of Drives

Drive Speed

SSD Cache

SSD Read Cache

File Workload

Custom Transfer Size (optional) Enter GB to calculate time-to-transfer

Estimated Read Speed

- MB/s

megabytes per second

Real-world speeds depend on hardware, protocol, network conditions, and workload.

⚡

Primary bottleneck: -

Time to Transfer

100 GB

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1 TB

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Times shown as fastest-slowest based on estimated speed range.

Component Breakdown

Network

Client drive

NAS storage

Estimated result

Unraid Write Speed (to array)

The above estimate is for reading from this array. Writing to an Unraid parity array is slower because parity must be recalculated on every write.

- MB/s

Not sure which connection type you have?

Get the free NBN Remote Access Logic Tree, one page covering every major AU ISP, whether they use CGNAT, and the fastest fix for each situation.

WAN / Internet Transfer Speed

Estimate how long a transfer would take over your internet connection. Select your ISP plan to pre-fill speeds.

Connection preset:

Defaults to Australian NBN tiers, if you're outside Australia, select your plan above or enter speeds manually.

Upload speed (Mbps)

Download speed (Mbps)

Upload: 100 GB

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Download: 100 GB

—

Upload: 1 TB

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Download: 1 TB

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Times assume 100% line utilisation. Real-world transfers typically achieve 80-90% of advertised speeds due to overhead and contention.

AU NBN Speed Tiers: Real-World NAS Transfer Rates

NBN speed tiers are advertised as download/upload Mbps, and what you actually get depends on your connection technology. Upload speed is the binding constraint for remote NAS access and off-site backup. FTTN and FTTC connections remain capped at 20-50 Mbps upload regardless of download tier. FTTP and HFC connections were upgraded to 50-200 Mbps upload from September 2025.

NBN Plan	Download	Upload	Real-world DL	Real-world UL
FTTN / FTTC (unchanged)
NBN 25	25 Mbps / 3.1 MB/s	5 Mbps / 0.6 MB/s	~2.5 MB/s	~0.5 MB/s
NBN 50	50 Mbps / 6.3 MB/s	20 Mbps / 2.5 MB/s	~5 MB/s	~2 MB/s
NBN 100 (most common)	100 Mbps / 12.5 MB/s	20 Mbps / 2.5 MB/s	~10 MB/s	~2 MB/s
FTTP / HFC (accelerated, from September 2025)
nbn Home Fast	500 Mbps / 62.5 MB/s	50 Mbps / 6.3 MB/s	~50 MB/s	~5 MB/s
nbn Home Superfast	750 Mbps / 94 MB/s	50 Mbps / 6.3 MB/s	~75 MB/s	~5 MB/s
nbn Home Ultrafast	1000 Mbps / 125 MB/s	100 Mbps / 12.5 MB/s	~90 MB/s	~9 MB/s
nbn Home Hyperfast (FTTP: 200 Mbps UL, HFC: 100 Mbps UL)	2000 Mbps / 250 MB/s	200 Mbps / 25 MB/s (FTTP)	~180 MB/s	~18 MB/s

Key insight: On FTTN or FTTC, a higher advertised download tier does not help remote NAS access or off-site backup, upload stays capped at 20-50 Mbps regardless of tier. On FTTP or HFC, NBN Co's September 2025 upgrade means upload is now 50-200 Mbps depending on tier, a genuine improvement for remote access. Check your connection technology (visible in your ISP account or the myNBN app) before assuming a plan upgrade won't help.

LAN Protocol Overhead: SMB vs NFS on 1 Gbps

1 Gbps Ethernet has a theoretical ceiling of 125 MB/s. Protocol choice and file size determine how close you get.

Protocol	Common use	Large file reads	Small file reads
SMB 3.x	Windows, macOS Finder	80-112 MB/s	5-30 MB/s
NFS v4	Linux clients, VMs, TrueNAS	90-118 MB/s	10-40 MB/s
SMB Multichannel (2× 1GbE)	Windows + Synology dual-port	160-220 MB/s	10-50 MB/s
AFP (legacy macOS)	Old macOS clients (deprecated)	50-90 MB/s	3-15 MB/s

For most AU home users on 1 Gbps LAN, SMB to a 4-bay Synology or QNAP NAS delivers 80-110 MB/s for large sequential files. The network becomes the ceiling before HDD array throughput in most 4-bay RAID 5 setups, so a 10GbE upgrade only helps if your drives exceed ~115 MB/s aggregate.

Example: Synology DS925+ Over SMB on 1 Gbps LAN

A DS925+ (4-bay, AMD Ryzen R1600) with 4× Seagate IronWolf 6 TB drives in RAID 5:

Sequential reads (large files, video): 100-112 MB/s: 1 Gbps network is the bottleneck, not the drives
Sequential writes: 85-100 MB/s over 1 Gbps SMB
Small files (<1 MB each): 5-20 MB/s: CPU and SMB metadata overhead dominate
Remote via NBN 100 on FTTN/FTTC (20 Mbps upload): ~2 MB/s ceiling, the NBN plan, not the NAS, sets this limit

CGNAT affects most AU residential users. Most Australian ISPs place residential customers behind CGNAT (Carrier-Grade NAT), which blocks standard port-forwarding for remote NAS access. Synology QuickConnect bypasses CGNAT via relay servers, but relay-routed traffic is typically capped at 5-10 MB/s. For faster remote access, you need a static IP (ask your ISP, usually $10-20/month extra) or a WireGuard VPN tunnel on the NAS.

How We Calculate

The estimator uses a bottleneck model with four components:

Network: practical throughput range for your link speed
Client drive: sustained read/write speed of your computer's storage
NAS storage: aggregate throughput based on drive type, RAID level, and drive count
Workload: penalty factor for small files (metadata overhead and IOPS limitations)

Your estimated speed is the minimum of all four components. The "primary limiter" shows which component is the bottleneck.

All throughput ranges are based on published benchmarks, manufacturer specifications, and typical real-world observations. They are shown as ranges rather than single numbers because actual performance varies with hardware, firmware, protocol overhead, and workload patterns.

Last reviewed: 24 August 2026

Related Tools & Guides

NAS Networking Guide (AU) → 10GbE NAS Networking Guide → Network Upgrade ROI Calculator → NAS Sizing Wizard → All Tools →

Frequently Asked Questions

Why do you show a range instead of an exact speed? +

Real-world transfer speeds depend on many variables, network overhead, protocol efficiency (SMB vs NFS), CPU load, caching, file sizes, and even antivirus scanning. A range is more honest than a single number. The primary limiter label tells you where to focus upgrades.

Why isn't my 10GbE network giving me 10GbE speeds? +

10GbE provides a theoretical maximum of 1,250 MB/s, but your actual speed is limited by the slowest component. If your NAS uses spinning HDDs in RAID 5, the drives may only deliver 300-450 MB/s, making them the bottleneck, not the network. The estimator identifies this for you.

Does SSD cache help with transfer speeds? +

SSD cache primarily improves random read performance and small file access. For large sequential transfers (e.g., copying video files), SSD cache provides minimal benefit because the data is read sequentially from the HDD array. The estimator adjusts its range based on your workload type.

Why are small files so much slower to transfer? +

Each file transfer involves metadata operations, opening, writing, closing, verifying. For large files, this overhead is negligible compared to the data transfer. For thousands of small files, the overhead dominates. A folder of 100,000 × 10KB files transfers much slower than a single 1GB file, even though the total data is the same.

Should I upgrade my network or my NAS drives first? +

Use the estimator to find your primary limiter. If it says "Network," upgrade your network first. If it says "NAS storage," faster or more drives will help more. In many home setups with HDDs, the NAS storage is the bottleneck well before 10GbE, meaning a 2.5GbE upgrade may be sufficient.

Does RAID type affect transfer speed? +

Yes. RAID types that stripe data across drives (RAID 0, 5, 6, 10) can read faster than a single drive because multiple drives contribute data simultaneously. RAID 1 (mirror) can also read faster than a single drive. Generally, more drives in a striped array means higher aggregate read throughput, up to the network or controller limit.

How does Unraid affect transfer speed? +

Reads: Unraid does not stripe data, each disk is formatted independently (XFS or BTRFS). For a single sequential read, throughput is capped at one data drive's sequential read speed (typically 100-160 MB/s for a 7200 RPM HDD). The parity disk plays no role in reads. Multiple concurrent users or streams can read from different disks simultaneously, but a single transfer will never exceed one drive's speed. On 1 GbE (~115 MB/s), the network is usually the bottleneck before the drives, which is why many Unraid users see no benefit from upgrading to 2.5 GbE for sequential reads.

Writes: Every write to the array must update the parity disk, and Unraid supports two write modes with different speed and power tradeoffs. Read/Modify/Write (the default) reads the existing data block and existing parity, calculates the new parity, and then writes both. Only the target data drive and the parity drive spin up. This is energy-efficient but slow: typically 20-40 MB/s. Turbo Write (Reconstruct Write) reads all data drives simultaneously to recalculate parity from scratch, then writes. All drives spin up and power consumption rises significantly, but speeds reach 40-120 MB/s. Neither mode achieves single-drive sequential write speed. You will always be slower than a drive's raw write throughput when writing to an Unraid parity array.

What about write speeds to NAS? +

This estimator focuses on read transfer speeds (copying from NAS to client), which is the most common scenario. For RAID 5/6, write speeds are typically 10-30% slower than reads due to parity calculation overhead. For RAID 1 and RAID 10, write speeds are similar to single-drive speeds. For Unraid, write speeds depend on write mode: Read/Modify/Write (the default) achieves 20-40 MB/s; Turbo Write (Reconstruct Write) achieves 40-120 MB/s. Neither Unraid write mode approaches single-drive sequential write speed. Parity recalculation is always the limiting factor. The Unraid Write Speed panel above your results shows the estimated write range for your selected mode.

How accurate are these estimates? +

The ranges are based on published benchmarks and typical observed performance. Most users should see speeds within the estimated range. However, specific hardware combinations, firmware versions, protocol settings, and network congestion can push speeds outside the range.

Why is my remote NAS access so slow in Australia? +

Two constraints are specific to Australian residential internet, and the first now depends on your connection technology. If you're on FTTN or FTTC, NBN upload speeds are still capped at 20-50 Mbps regardless of download tier. If you're on FTTP or HFC, NBN Co's September 2025 upgrade lifted upload to 50-200 Mbps depending on tier (Home Fast: 50 Mbps, Home Superfast: 50 Mbps, Home Ultrafast: 100 Mbps, Home Hyperfast: up to 200 Mbps on FTTP). Either way, remote NAS access is upload-limited, so upload speed is what matters, not download tier. Second, most AU residential ISPs use CGNAT (Carrier-Grade NAT), which blocks standard port forwarding. Synology QuickConnect bypasses CGNAT via relay servers, but relay-routed traffic is typically capped at 5-10 MB/s. For faster remote access, you need a static IP (ask your ISP, usually $10-20/month extra) or a WireGuard VPN tunnel on the NAS.