NAS File Transfer Speed Estimator
This estimator works out how fast a copy to or from your NAS will run and how long it will take, from the network link, the drives at each end, the RAID level or Unraid write mode, and how many files you are copying. It names the part that limits the copy, and it also times transfers over your internet connection using nbn's published speed tiers.
A faster network does not guarantee a faster copy. A copy runs at the speed of its slowest part: the drives it reads from, the network in between, or the drive it writes to. Thousands of small files add handling time on top. Pick the direction, your network and the storage at each end to see a speed range, the transfer time and what to upgrade first, if anything.
Time to transfer
Fastest to slowest, from the ends of the estimated range. Includes the per-file handling time.
Each part of the copy
Assumptions this result used
Over the internet: remote access and off-site copies
Copying from your NAS while you are away uses your home upload; copying to it from elsewhere uses your home download. Pick an nbn tier to fill in the plan speeds, or enter your own. A speed you measured is used as it is.
| Line rate | Planning rate (75%) | Measured | |
|---|---|---|---|
| Upload | - | - | - |
| Download | - | - | - |
Times run from the line rate (fastest) to the planning rate of 75% of the plan speed, an NTK planning assumption, or use your measured speed alone. They count the bytes only: many small files add time, and so does a slow NAS or relay.
How we calculate
A copy passes through three stages: the drive it is read from, the network, and the drive it is written to. Each stage has a speed range in MB/s. The copy moves its bytes at the speed of the slowest stage; nothing is multiplied together. On top of the bytes, every file costs a little handling time (creating it, writing its details, closing it), divided by the number of files copied at once:
time = size ÷ slowest stage + files × time per file ÷ files at once
- Direction matters. NAS to computer reads the NAS and writes the computer's drive; the other way reads the computer and writes the NAS. A RAID 5 array or an Unraid array writes slower than it reads, so the two directions give different answers.
- Network: the link's line rate (1 GbE = 1,000 Mbps = 125 MB/s) times an NTK planning range of 80% to 94% for protocol overhead. Several links count together only when you say SMB Multichannel is active.
- Drives: per-drive planning ranges; striped RAID adds the data drives together for reads and for writes, and parity writes run at a planning share of that; a desktop NAS array tops out at a planning ceiling however many drives it has.
- Files: from your file count and size, or an average file size for each preset. When handling the files takes longer than moving the bytes, the estimate says the files, not the hardware, set the time.
- Measured beats estimated. A copy speed you measured replaces the whole model; a measured internet speed replaces the plan speed. Nothing is applied on top of a measurement.
- Units: decimal throughout. 1 GB = 109 bytes, 1 TB = 1,000 GB; Mbps is megabits, MB/s is megabytes, 8 bits to a byte.
Every figure is listed under "Assumptions this estimator uses" below, labelled as a figure a primary source states or as an NTK planning assumption. None of them is a benchmark of a particular NAS.
Worked examples
A 4-bay NAS over 1 GbE. Four 7,200 RPM drives in RAID 5, copying large files to a computer with an NVMe SSD. The array reads 306 to 459 MB/s, the 1 GbE link carries 100 to 117.5 MB/s, so the network sets the speed and 100 GB takes 14 min to 17 min.
The same NAS, written to over 10 GbE. Writing to the four-drive RAID 5 runs at 183.6 to 413.1 MB/s: the three data drives striped, then the parity-write assumption. Now the array, not the network, is the limit, and 100 GB takes 4 min to 9 min. With eight drives the array writes 428.4 to 800 MB/s: more drives write faster, they do not just read faster.
A million small files. The same 100 GB from the first example as 1,000,000 files of 100 KB takes 1 h 38 min to 5 h 50 min one file at a time, against 14 min to 17 min as a hundred large files. Copying 8 files at once brings it to 25 min to 58 min. The hardware is the same in all three.
Writing to Unraid. Copying 100 GB to an Unraid parity array in its default Read/Modify/Write mode, at the documented 20 to 40 MB/s, takes 42 min to 1 h 23 min whatever the network.
Over the internet. Uploading 100 GB on a 20 Mbps upload takes 11 h 7 min at the full line rate and 14 h 49 min at the 75% planning rate.
Method last reviewed: 2026-10-14. Sources last checked: 2026-10-07.
What each Ethernet link can carry
The line rate is the link's speed in megabits per second divided by 8. The planning range is what this estimator expects a single copy to get after protocol overhead (80% to 94% of the line rate, an NTK planning assumption). The time is for 100 GB of large files when nothing else is slower.
| Link | Line rate (MB/s) | Planning range (MB/s) | 100 GB takes |
|---|---|---|---|
| 100 Mbps Ethernet | 12.5 | 10 to 11.8 | 2 h 22 min to 2 h 47 min |
| 1 GbE | 125 | 100 to 117.5 | 14 min to 17 min |
| 2.5 GbE | 312.5 | 250 to 293.8 | 6 min to 7 min |
| 5 GbE | 625 | 500 to 587.5 | 3 min |
| 10 GbE | 1,250 | 1,000 to 1,175 | 1 min to 2 min |
Two ports, SMB Multichannel and jumbo frames
Without SMB Multichannel, one SMB session uses a single network adapter, so two 1 GbE adapters cannot give 2 Gbps to that session. With Multichannel, SMB can use the combined bandwidth of the adapters. (Microsoft Learn, checked 2026-10-07)
A NIC team without SMB Multichannel still gives SMB only one TCP/IP connection, which limits how much of the team's bandwidth one transfer can use. (Microsoft Learn, checked 2026-10-07)
So the estimator adds links together only when you tick that SMB Multichannel is active; two ports without it give one copy one link's speed. Several copies to different computers can still use both ports between them.
This estimator applies no jumbo-frame bonus. Jumbo frames only work when every device in the path uses the same frame size, and any gain depends on the hardware and the workload; we found no source for a fixed figure.
SMB signing and SMB encryption slow SMB transfers by an amount that depends mainly on the CPU: core count and speed, and how busy the cores are. Windows 11 24H2 and Windows Server 2025 require SMB signing by default. (Microsoft Learn, checked 2026-10-07) If you know the ceiling your hardware reaches with signing or encryption on, enter it under "More options".
RAID writes, Unraid and SSD cache
Striped RAID spreads both reads and large writes across every drive that holds data, so a bigger array writes faster as well as reading faster. Parity RAID (5 and 6) does extra work on writes, and how much depends on the NAS, the filesystem, caching and whether writes fill whole stripes; there is no fixed percentage. This estimator therefore plans parity writes as a share of the striped rate (an NTK planning assumption, listed below) instead of a flat "writes are X% slower" rule. RAID 1 writes at one drive's speed; RAID 10 stripes across the mirrored pairs.
Unraid does not stripe across drives: each file is stored on a single disk. (Unraid documentation, checked 2026-10-06) For a normal read of a file that is not in a cache, the copy therefore runs at the speed of the disk holding it, and more data disks do not make one copy faster.
Unraid's documentation gives typical array write speeds of 20 to 40 MB/s for Read/Modify/Write (the default) and 40 to 120 MB/s for Turbo Write (reconstruct write), which needs every array drive spinning and healthy. (Unraid documentation, checked 2026-10-07)
Unraid's documentation gives typical sequential speeds of 70 to 250 MB/s for a single hard drive (depending on model, age and where the data sits) and 400 to 550 MB/s for a SATA SSD. (Unraid documentation, checked 2026-10-07)
Writes that land on an Unraid cache pool, or on a pool outside the parity array, are not limited by the parity write modes; choose the SSD pool option for those.
An SSD cache speeds up a copy only when the files are already in it. The estimator applies cache speed only when you tick that they are, and only for copies from the NAS.
nbn speed tiers and internet transfers
Remote access to a NAS and off-site copies are usually limited by the home upload, not the download tier. In nbn's current tiers the highest upload on FTTN and FTTB is 20 Mbps, and on FTTC 20 Mbps, whatever the download tier. Uploads of 50 Mbps and more come with Home Hyperfast, Home Ultrafast, Home Superfast and Home Fast II, which nbn offers on FTTP and HFC only.
nbn speeds are wholesale: the maximum nbn provides to internet providers. Where a tier is a range, the maximum can fall anywhere in it, and the lower figure is not a minimum speed. (nbn co (nbnco.com.au), checked 2026-10-07)
| Tier | Technology | Download (Mbps) | Upload (Mbps) | Upload (MB/s, line rate) | 100 GB upload |
|---|---|---|---|---|---|
| Home Hyperfast | FTTP | 2,000 | 200 | 25 | 1 h 7 min to 1 h 29 min |
| Home Hyperfast | HFC | 2,000 | 100 | 12.5 | 2 h 13 min to 2 h 58 min |
| Home Ultrafast | FTTP | 1,000 | 100 | 12.5 | 2 h 13 min to 2 h 58 min |
| Home Ultrafast | HFC | 1,000 | 100 | 12.5 | 2 h 13 min to 2 h 58 min |
| Home Superfast | FTTP | 750 | 50 | 6.25 | 4 h 27 min to 5 h 56 min |
| Home Superfast | HFC | 750 | 50 | 6.25 | 4 h 27 min to 5 h 56 min |
| Home Fast II | FTTP | 500 | 50 | 6.25 | 4 h 27 min to 5 h 56 min |
| Home Fast II | HFC | 500 | 50 | 6.25 | 4 h 27 min to 5 h 56 min |
| Home Fast I | FTTC | 50 to 100 | 20 | 2.5 | 11 h 7 min to 14 h 49 min |
| Home Fast I | FTTN | 25 to 100 | 5 to 20 | 0.63 to 2.5 | 11 h 7 min to 2 days 11 h |
| Home Fast I | FTTB | 25 to 100 | 5 to 20 | 0.63 to 2.5 | 11 h 7 min to 2 days 11 h |
| Home Standard | FTTP | 50 | 20 | 2.5 | 11 h 7 min to 14 h 49 min |
| Home Standard | FTTC | 50 | 20 | 2.5 | 11 h 7 min to 14 h 49 min |
| Home Standard | HFC | 50 | 20 | 2.5 | 11 h 7 min to 14 h 49 min |
| Home Standard | FTTN | 25 to 50 | 5 to 20 | 0.63 to 2.5 | 11 h 7 min to 2 days 11 h |
| Home Standard | FTTB | 25 to 50 | 5 to 20 | 0.63 to 2.5 | 11 h 7 min to 2 days 11 h |
| Home Basic II | FTTP | 25 | 10 | 1.25 | 22 h 13 min to 1 day 5 h |
| Home Basic II | FTTC | 25 | 10 | 1.25 | 22 h 13 min to 1 day 5 h |
| Home Basic II | HFC | 25 | 10 | 1.25 | 22 h 13 min to 1 day 5 h |
| Home Basic II | FTTN | 25 | 5 to 10 | 0.63 to 1.25 | 22 h 13 min to 2 days 11 h |
| Home Basic II | FTTB | 25 | 5 to 10 | 0.63 to 1.25 | 22 h 13 min to 2 days 11 h |
| Home Basic I | all fixed line | 12 | 1 | 0.13 | 9 days 6 h to 12 days 8 h |
| Tier | Download (Mbps) | Upload (Mbps) | Upload (MB/s, line rate) | 100 GB upload |
|---|---|---|---|---|
| Fixed Wireless Superfast | 400 | 10 to 40 | 1.25 to 5 | 5 h 33 min to 1 day 5 h |
| Fixed Wireless Home Fast | 250 | 8 to 20 | 1 to 2.5 | 11 h 7 min to 1 day 13 h |
| Fixed Wireless Plus | 100 | 20 | 2.5 | 11 h 7 min to 14 h 49 min |
| Fixed Wireless Basic II | 25 | 5 | 0.63 | 1 day 20 h to 2 days 11 h |
| Fixed Wireless Basic I | 12 | 1 | 0.13 | 9 days 6 h to 12 days 8 h |
Speeds as nbn co states them, checked 2026-10-07 (nbn speed plans). The time runs from the top of the upload range at the full line rate to the bottom of the range at the 75% planning rate.
Line rate, planning rate and measured speed
The internet box keeps three figures apart: the plan's line rate, a planning rate of 75% of it (an NTK planning assumption for sustained copies, not a measured figure), and any speed you measured, which replaces the other two.
In the ACCC's latest report (measurements collected March 2026), NBN fixed line services averaged 90.4% of their plan upload speed during busy hours. This measures the line, not cloud backup software. (ACCC, checked 2026-10-07)
In the ACCC's latest report, NBN fixed wireless services averaged 70.1% of plan upload speed across all hours and 63.7% in busy hours. (ACCC, checked 2026-10-07)
The ACCC Measuring Broadband Australia program concluded at the end of June 2026; its final performance report was released on 17 June 2026. (ACCC, checked 2026-10-07)
Remote access: CGNAT, relays and VPNs
Some providers place services behind CGNAT (carrier-grade NAT), which stops inbound connections such as port forwarding from reaching your NAS. Whether your provider does, and whether it offers a public or static IP address and what that costs, varies by provider and plan. Ask your provider, or compare plans in the NBN Plan Finder.
Synology says a relayed QuickConnect connection may be slow because of longer network latency, and recommends port forwarding for better performance. This help page gives no speed figure or cap. (Synology DSM Help, checked 2026-10-07)
A VPN to your home network, run on the NAS or the router, is another way in that does not depend on a relay. Whatever the route, the home upload in the table above is the ceiling for copies from the NAS.
Not sure which connection type you have?
Get the free NBN Remote Access Logic Tree, a one-page guide to working out whether port forwarding will work on your connection and the fastest fix for each situation.
Assumptions this estimator uses
Each figure below drives the calculator. "NTK planning assumption" means an editorial planning figure chosen by Need to Know IT, not a measurement or a vendor benchmark. A source figure is quoted from the source named, with the date we checked it.
| Assumption | Type | Evidence |
|---|---|---|
| NTK planning assumption: a wired Ethernet link moves 80% to 94% of its line rate as file data, after protocol overhead | NTK planning assumption | None: NTK planning figure |
| NTK planning assumption: 75% of the plan's speed | NTK planning assumption | None: NTK planning figure |
| NTK planning assumption: one 7,200 RPM hard drive moves 120 to 180 MB/s sequentially (Unraid documents 70 to 250 MB/s across drives) | NTK planning assumption | Unraid documentation, checked 2026-10-07 |
| NTK planning assumption: one 5,400 RPM class hard drive moves 80 to 140 MB/s sequentially (Unraid documents 70 to 250 MB/s across drives) | NTK planning assumption | Unraid documentation, checked 2026-10-07 |
| A SATA SSD moves 400 to 550 MB/s sequentially (typical range in the Unraid documentation) | Source figure | Unraid documentation, checked 2026-10-07 |
| NTK planning assumption: an NVMe SSD sustains 1,500 to 3,500 MB/s sequentially | NTK planning assumption | None: NTK planning figure |
| NTK planning assumption: striped arrays add 85% of one drive's speed for each drive that holds data | NTK planning assumption | None: NTK planning figure |
| NTK planning assumption: a mirror reads about 1.3 times as fast as one drive, because reads can come from either copy | NTK planning assumption | None: NTK planning figure |
| NTK planning assumption: large sequential writes to RAID 5 or RAID 6 run at 60% to 90% of the striped rate of the data drives, for parity work and partial stripes | NTK planning assumption | None: NTK planning figure |
| NTK planning assumption: a typical desktop NAS tops out around 640 to 800 MB/s from a hard drive array, however many drives it has (controller and CPU) | NTK planning assumption | None: NTK planning figure |
| NTK planning assumption: an SSD pool writes at about 90% of its read speed | NTK planning assumption | None: NTK planning figure |
| Unraid array write, Read/Modify/Write (the default): typically 20 to 40 MB/s (Unraid documentation) | Source figure | Unraid documentation, checked 2026-10-07 |
| Unraid array write, Turbo Write (reconstruct write): typically 40 to 120 MB/s, with every array drive spinning (Unraid documentation) | Source figure | Unraid documentation, checked 2026-10-07 |
| NTK planning assumption: each file costs 5 to 20 milliseconds of handling (create, metadata, close) on a single-threaded copy, on top of its bytes | NTK planning assumption | Microsoft Learn, checked 2026-10-07 |
| NTK planning assumption: "large files" means an average file of about 1 GB (video, disk images, archives) | NTK planning assumption | None: NTK planning figure |
| NTK planning assumption: "mixed files" means an average file of about 5 MB (photos, documents, music) | NTK planning assumption | None: NTK planning figure |
| NTK planning assumption: "many small files" means an average file of about 100 KB (source code, thumbnails, mail) | NTK planning assumption | None: NTK planning figure |
Sources this page uses
nbn speed tiers (nbn co)
- nbn Home Hyperfast: 2000 Mbps download; upload 200 Mbps on FTTP and 100 Mbps on HFC. Available on FTTP and HFC only. (nbn co (nbnco.com.au), checked 2026-10-07)
- nbn Home Ultrafast: about 1000 Mbps download and 100 Mbps upload. Available on FTTP and HFC only. (nbn co (nbnco.com.au), checked 2026-10-07)
- nbn Home Superfast: 750 Mbps download and 50 Mbps upload. Available on FTTP and HFC only. (nbn co (nbnco.com.au), checked 2026-10-07)
- nbn Home Fast II: 500 Mbps download and 50 Mbps upload. Available on FTTP and HFC only. (nbn co (nbnco.com.au), checked 2026-10-07)
- nbn Home Fast I: on FTTC, 50 to 100 Mbps download and 20 Mbps upload; on FTTN and FTTB, 25 to 100 Mbps download and 5 to 20 Mbps upload. Available on FTTN, FTTC and FTTB. (nbn co (nbnco.com.au), checked 2026-10-07)
- nbn Home Standard: on FTTP, FTTC and HFC, 50 Mbps download and 20 Mbps upload; on FTTN and FTTB, 25 to 50 Mbps download and 5 to 20 Mbps upload. Available on all fixed line technologies. (nbn co (nbnco.com.au), checked 2026-10-07)
- nbn Home Basic II: 25 Mbps download; upload 10 Mbps on FTTP, FTTC and HFC, 5 to 10 Mbps on FTTN and FTTB. Available on all fixed line technologies. (nbn co (nbnco.com.au), checked 2026-10-07)
- nbn Home Basic I: 12 Mbps download and 1 Mbps upload. Available on all fixed line technologies. (nbn co (nbnco.com.au), checked 2026-10-07)
- nbn Fixed Wireless Superfast: potential maximum 400 Mbps download and 10 to 40 Mbps upload; maximum wholesale peak hour speed 357/25 Mbps. Eligible premises only. (nbn co (nbnco.com.au), checked 2026-10-07)
- nbn Fixed Wireless Home Fast: potential maximum 250 Mbps download and 8 to 20 Mbps upload; maximum wholesale peak hour speed 187/15 Mbps. Eligible premises only. (nbn co (nbnco.com.au), checked 2026-10-07)
- nbn Fixed Wireless Plus: potential maximum 100 Mbps download and 20 Mbps upload; maximum wholesale peak hour speed 100/14 Mbps. (nbn co (nbnco.com.au), checked 2026-10-07)
- nbn Fixed Wireless Basic II: potential maximum 25 Mbps download and 5 Mbps upload. (nbn co (nbnco.com.au), checked 2026-10-07)
- nbn Fixed Wireless Basic I: potential maximum 12 Mbps download and 1 Mbps upload. (nbn co (nbnco.com.au), checked 2026-10-07)
- nbn speeds are wholesale: the maximum nbn provides to internet providers. Where a tier is a range, the maximum can fall anywhere in it, and the lower figure is not a minimum speed. (nbn co (nbnco.com.au), checked 2026-10-07)
Measured broadband (ACCC)
- In the ACCC's latest report (measurements collected March 2026), NBN fixed line services averaged 90.4% of their plan upload speed during busy hours. This measures the line, not cloud backup software. (ACCC, checked 2026-10-07)
- In the ACCC's latest report, NBN fixed wireless services averaged 70.1% of plan upload speed across all hours and 63.7% in busy hours. (ACCC, checked 2026-10-07)
- The ACCC Measuring Broadband Australia program concluded at the end of June 2026; its final performance report was released on 17 June 2026. (ACCC, checked 2026-10-07)
SMB file sharing (Microsoft)
- Without SMB Multichannel, one SMB session uses a single network adapter, so two 1 GbE adapters cannot give 2 Gbps to that session. With Multichannel, SMB can use the combined bandwidth of the adapters. (Microsoft Learn, checked 2026-10-07)
- A NIC team without SMB Multichannel still gives SMB only one TCP/IP connection, which limits how much of the team's bandwidth one transfer can use. (Microsoft Learn, checked 2026-10-07)
- Copying large numbers of small files (under 1 MB each) is slow by design with single-threaded copy tools: every file has a fixed creation cost, so more time goes on creating files than on moving their data. (Microsoft Learn, checked 2026-10-07)
- SMB signing and SMB encryption slow SMB transfers by an amount that depends mainly on the CPU: core count and speed, and how busy the cores are. Windows 11 24H2 and Windows Server 2025 require SMB signing by default. (Microsoft Learn, checked 2026-10-07)
Unraid
- Unraid's documentation gives typical array write speeds of 20 to 40 MB/s for Read/Modify/Write (the default) and 40 to 120 MB/s for Turbo Write (reconstruct write), which needs every array drive spinning and healthy. (Unraid documentation, checked 2026-10-07)
- Unraid's documentation gives typical sequential speeds of 70 to 250 MB/s for a single hard drive (depending on model, age and where the data sits) and 400 to 550 MB/s for a SATA SSD. (Unraid documentation, checked 2026-10-07)
Synology
- Synology says a relayed QuickConnect connection may be slow because of longer network latency, and recommends port forwarding for better performance. This help page gives no speed figure or cap. (Synology DSM Help, checked 2026-10-07)