Have you ever looked at your torrent details and seen a line that says Wasted, with a number of hashfails next to it?
It looks worrying. Wasted sounds like a loss, and a fail sounds like something is broken. Many people ask whether they should be concerned, whether their file is damaged, or whether their computer has a problem.
In most cases, the answer is no. A hashfail is a piece that did not pass a check and was thrown away. Wasted data is the total amount of data that your client received but could not use. A small amount of both is a normal part of every torrent download. The check is what keeps your final file correct.
In this guide, we’ll explain what torrent hashfails and wasted data are, how the two numbers are connected, how to find them in your client, how much is normal, what causes high numbers, and how to bring them down.
What Is a Hashfail?
A torrent file contains a hash for every piece of the content. A hash is a short code that is calculated from the data of a piece. If the data changes, even by a single bit, the code changes.
When your client receives a full piece, it calculates the hash of what it received and compares it to the hash in the torrent. If they match, the piece is good. If they do not match, the check fails. That is a hashfail.
The client then discards the piece and downloads it again. The bad data never becomes part of your file.
The method is part of the official BitTorrent specification, which describes how pieces are verified. Our guide on the qBittorrent hashing error goes deeper into the causes and the repair steps.
What Is Wasted Data?
Wasted data is the amount of data that your client downloaded but did not use. It has two main parts.
- Failed data: pieces that failed the hash check and were discarded.
- Redundant data: blocks that arrived more than once, for example when two peers sent the same block, so only one copy was needed.
Both are counted in the amount you downloaded, but neither ends up in your final files.
The libtorrent torrent status reference lists failed bytes and redundant bytes as separate values, and clients that use this library, including qBittorrent, show a combined waste figure.
How Hashfails and Wasted Data Are Connected
Think of wasted data as the total, and hashfails as one source of it.
- Every hashfail adds the size of a whole piece to the wasted amount, because the full piece is discarded.
- Redundant blocks add to the wasted amount as well, but they do not count as hashfails.
So the number of hashfails and the amount of wasted data tell you different things. The hashfail count tells you how many pieces failed. The wasted amount tells you how much data that cost, plus the duplicates.
Some clients show both together in one line, for example Wasted 12.4 MB with 3 hashfails. If your client shows only the wasted amount, you can still estimate the number of failed pieces from the piece size.
Where to Find the Numbers in Your Client
qBittorrent
Select a torrent and open the General tab at the bottom of the window. Look for Wasted next to the Downloaded value. You can also open Tools, then Statistics, to see Session Waste, which shows the total since you opened the client.
uTorrent and BitTorrent
Select a torrent and open the General section of the details panel. It lists Wasted, and often shows the number of hashfails in brackets.
Other clients
Most clients have a similar field in the details window. The name may be Wasted, Corrupt, Failed, or Redundant. If you cannot find it, compare the amount downloaded with the amount of data in the files.
How to Calculate the Waste Percentage
A percentage makes it easier to decide whether the number is normal.
Divide the wasted amount by the size of the torrent, and multiply by 100.
For example, if a 10 GiB torrent shows 150 MiB wasted, that is about 1.5 percent. If it shows 1 GiB wasted, that is about 10 percent.
You can also estimate the failed pieces. If the piece size is 4 MiB and the wasted amount is 40 MiB, up to 10 pieces failed or arrived twice.
How Much Wasted Data Is Normal?
There is no exact line, but these ranges are a useful guide.
- Under 1 percent: very good. This is common on healthy torrents with fast, reliable peers.
- Between 1 and 5 percent: normal. Some failed pieces and duplicates happen on most downloads.
- Between 5 and 10 percent: higher than usual. Check the torrent, the peers, and your system.
- Above 10 percent: something is wrong or the swarm is unusually bad. Investigate.
Small torrents can show a high percentage with only a little data, because one failed piece is a large share of the total. Large pieces also give higher numbers. Always look at the number of hashfails and the piece size, not only the percentage.
Our guide on why a torrent client shows more data downloaded than the file size explains how this waste adds to the Downloaded value.
What Causes Hashfails?
Peers that send bad data
This is the most common cause. A peer may have a faulty disk, bad memory, or a buggy client, or it may send bad data on purpose. Your hash check catches it and you download the piece again from someone else.
Faulty memory on your computer
If your own memory is unstable, data can change before it is written. Pieces from good peers then fail the check. A sign of this is failures across many peers and many torrents.
A failing drive
If the drive returns data different from what was written, the piece fails. A sign is a recheck that finds problems in a torrent that was complete.
Software that changes files
Antivirus programs, sync tools, and editors can change files that a torrent is using. This causes failures on the next check.
Interrupted writes
A crash or a power loss during a write can leave a piece half written.
A bad source
Some torrents contain pieces that are wrong in the swarm itself, for example if the first uploader had a damaged copy. In that case, many peers share the same bad data, and no client can fix it.
What Causes Redundant Data?
Redundant data appears when the same block arrives twice. The common reasons are these.
- Endgame mode, where the client asks several peers for the last blocks at the same time.
- Slow replies, where the client asks another peer after a delay, and the first peer then answers too.
- Peers that disconnect after the client has asked for blocks.
- A web seed and peers sending the same block.
Redundant data is a sign of an active, healthy download, not a sign of a problem. It is usually small.
Hashfails vs Other Errors
People often mix hashfails with other messages. It helps to separate them.
- A hashfail is about data content. The piece arrived but did not match.
- An I/O error is about reading or writing a file. The data could not be saved or read. Our guide on the qBittorrent I/O error on Windows covers it.
- Missing Files means the client cannot find the files at the save path.
- Stalled means no data is moving, which is a connection issue.
- A failed recheck means pieces on your disk no longer match.
Each needs a different fix. A hashfail is not a disk error, and a disk error is not a hashfail, although a failing disk can cause both.
What to Do When the Numbers Are High
Step 1: Check whether the problem is one torrent or all of them
If only one torrent has a high number, the source or the swarm is likely the cause. If all torrents do, look at your computer.
Step 2: Look at the pattern over time
Does the waste grow steadily, or did it jump at one moment? A jump may match a crash, a disconnect, or a recheck.
Step 3: Run a Force recheck
Right-click the torrent and choose Force recheck. This tells you whether the data on your disk is good. If it passes, the failures were temporary and handled.
Step 4: Test your memory and drive
If many torrents show failures, run a memory test and check the health of your drive. Our hashing guide explains how.
Step 5: Ban a bad peer
If the Peers tab shows one peer that keeps sending bad data, you can ban it. The client usually does this on its own after repeated failures.
Step 6: Exclude the folder from scanners and sync tools
Add the download folder to your antivirus exclusions, and keep it out of synced folders.
Step 7: Try a better source
If the torrent itself is bad, no setting will fix it. Find another source for the same content.
Does High Waste Hurt Anything?
Waste costs you bandwidth and time. If your connection is slow or has a data cap, the extra data matters more.
It does not damage your files. Only pieces that pass the check are kept. It also does not mean that you are uploading bad data, because you only share pieces that you have verified.
If you seed, a failed recheck of a finished torrent is the one case where you should stop and repair first, so you do not share bad pieces.
Do Hashfails Happen When You Seed?
Hashfails count pieces that you received. A torrent that you only seed does not receive new pieces, so it does not gain new hashfails. If you see new failures on a seeding torrent, it means a recheck found damaged data, or you are downloading some missing pieces again.
Old hashfail counts stay with the torrent for as long as the client keeps its statistics.
Examples
Example 1: A 6 GiB torrent shows 60 MiB wasted and 4 hashfails
That is about 1 percent. It is normal and needs no action.
Example 2: A 700 MiB torrent shows 70 MiB wasted and 6 hashfails
That is about 10 percent, but the torrent is small and has large pieces. Six failed pieces of 8 MiB is 48 MiB. A recheck that passes means all is well.
Example 3: Every torrent shows many hashfails
Your computer is the likely cause. Test the memory and the drive, and check for overclocking.
Example 4: Hashfails keep growing at 99 percent
The same piece keeps failing. This can come from a bad peer, a bad source, or a hardware problem. Our guide on how to fix a torrent stuck at 99.9 percent explains what to check.
Example 5: Wasted is high but hashfails is zero
The waste is redundant data. It usually comes from endgame mode or from many slow peers. It is harmless.
Pieces, Blocks, and Why One Bad Block Costs a Whole Piece
Torrent data is divided into pieces, and pieces are downloaded in smaller blocks, commonly 16 KiB each. The hash in a standard torrent covers a whole piece, not a single block.
That is why a single bad block can waste so much. Suppose a piece is 4 MiB, which is 256 blocks. Peers send you those blocks, maybe from several sources. If one block is wrong, the hash of the whole piece fails, and the client cannot tell which of the 256 blocks was the bad one. It discards all 4 MiB and starts again.
Newer torrents that use version 2 of the format store hashes in a tree that covers each 16 KiB block. This lets a client find the exact bad block and re-download only that block. The change is described in the official specification for version 2 torrents. Hybrid torrents carry both kinds of hashes, so old and new clients can use them. If you use a client that supports version 2, you may see less waste on those torrents.
How Clients Handle Peers That Send Bad Data
When a piece fails, the client remembers which peers sent blocks for it. If the same peer is linked to failures again and again, the client can ban it.
Some clients use a method where they download the failed piece again with blocks from only one peer. If it then passes, the client knows that the earlier mix contained a bad block. By comparing, it can identify the guilty peer and ban only that one.
This is why waste often grows quickly at first and then stops. A bad peer is found, banned, and the rest of the swarm gives you good data. If the waste keeps growing with no end, the cause may be on your side.
You can also act yourself. Open the Peers tab, right-click a peer, and choose the option to ban it. Do this only when you are sure, because banning healthy peers slows your download.
Worked Examples
Example A: A large torrent with small pieces
A 40 GiB torrent has 1 MiB pieces. During the download, 120 pieces fail the check. That is 120 MiB of failed data. Add 200 MiB of duplicate blocks from endgame mode, and the waste is about 320 MiB, or 0.8 percent. This is a very good result.
Example B: A small torrent with large pieces
A 1.5 GiB torrent has 16 MiB pieces. Five pieces fail. That is 80 MiB, or 5.2 percent. The percentage looks high, but only five pieces failed. It is not a cause for concern unless the number keeps growing.
Example C: A damaged drive
You download a 20 GiB torrent and the waste shows 2.5 GiB, which is 12.5 percent. The torrent finishes, but a recheck later fails on 30 pieces. Other torrents show the same pattern. This points to the drive or memory. Test them before you download more.
A Table of Causes, Signs, and Tests
Here is a quick guide in words. Find the sign that matches what you see, and use the test next to it.
- Sign: waste on one torrent only, from one or two peers, then it stops. Cause: a bad peer. Test: none needed.
- Sign: waste on one torrent that never stops, with a bad swarm. Cause: a bad source. Test: try another source.
- Sign: waste on all torrents, from many peers. Cause: your memory or storage. Test: run a memory test and a drive check.
- Sign: a finished torrent that fails a recheck. Cause: a failing drive, a program that changed files, or a bad copy. Test: check the drive, and exclude the folder from scanners.
- Sign: waste appears after you changed memory settings. Cause: an unstable overclock. Test: return to default settings.
- Sign: high waste but no hashfails. Cause: redundant blocks. Test: none needed.
How to Test Your Memory and Drive in Short
You do not need to be an expert to run the basic tests.
Memory
- Run Windows Memory Diagnostic from the Start menu. It restarts the computer and checks the memory.
- For a stronger test, use MemTest86 from a USB drive and let it run several passes.
- If you see errors, remove sticks one at a time to find the bad one, and turn off any overclock or memory profile.
Drive
- Run the Windows disk check on the drive that holds your downloads.
- Look at the drive health with a SMART tool.
- For external drives, try a different cable and port.
Our guide on the qBittorrent hashing error gives more steps for these tests.
Can Your Network Cause Hashfails?
Almost never. The protocols that carry torrent data, such as TCP, check for errors in transit. If a packet is damaged, it is sent again. So an unstable connection usually causes slow speeds and disconnects, not hashfails.
A VPN or a Wi-Fi network that drops often can cause redundant data, because the client asks again for blocks that were lost. But it does not cause bad data inside a piece. If you see many hashfails and you use an unstable network, look at your memory and drive first, because the network is rarely the source.
How to Track Waste Over Time
A single number is hard to judge. A few simple notes make it clear.
- Note the wasted amount and the percentage at the start of a download.
- Check again when the torrent is half done and when it finishes.
- Note whether the amount jumped at certain times.
- Compare several torrents of different sizes and piece sizes.
If every torrent has a similar percentage, you have a stable baseline. If one torrent is far above that baseline, look at that torrent. If the baseline itself rises over weeks, something changed on your system, such as a driver, a drive, or memory settings.
Does Waste Affect Private Tracker Ratios?
This depends on the tracker. Trackers calculate your ratio from the amounts that your client reports. Some clients report all downloaded data, and some report only useful data. If you are close to a ratio limit and you see heavy waste, read the tracker’s rules or ask its support how it counts downloaded data.
Do not try to change what your client reports. Trackers treat that as cheating. A simple solution is to keep your system stable, so waste stays low.
Glossary
- Hash: a short code calculated from data, used to check that the data is unchanged.
- Piece: a part of the torrent with its own hash.
- Block: a smaller part of a piece that peers send one at a time.
- Hashfail: a piece that failed the hash check.
- Redundant data: blocks that arrived more than once.
- Wasted data: failed and redundant data together.
- Swarm: all the peers that share one torrent.
- Seed: a peer with the complete torrent.
- Recheck: a full verification of the files on your disk.
Common Myths About Hashfails and Waste
- Myth: Hashfails mean your file is corrupted. Fact: failed pieces are discarded, so the file stays correct.
- Myth: Waste means your connection is bad. Fact: much of it comes from other peers or from endgame mode.
- Myth: You should delete the torrent when hashfails appear. Fact: a recheck and a re-download of the missing pieces are enough.
- Myth: Zero waste is the goal. Fact: some waste is normal, and trying to remove it all is not practical.
- Myth: A VPN causes hashfails. Fact: it can cause duplicate data, but not bad data inside pieces.
A Short Checklist
- Read the number of hashfails and the wasted amount.
- Turn the amount into a percentage of the torrent size.
- Check the piece size.
- Decide whether the number is normal.
- If it is high, check whether it affects one torrent or all.
- Run a Force recheck.
- Test the memory and the drive if many torrents are affected.
- Exclude the folder from scanners and sync tools.
- Replace a bad source.
How Hashfails Differ Between Downloading and Rechecking
The word hashfail is used in two situations, and they mean different things.
- During a download: a piece arrived from the network and failed the check right away. The cause is usually a peer, or memory on your computer.
- During a recheck: a piece that was already on your disk no longer matches. The cause is usually the drive, another program, or a file that was changed or moved.
When you see failures, ask which one you are looking at. A failure during a download is rarely a reason to worry. A failure during a recheck on a torrent that was complete means the data on your disk changed, and you should find out why before you trust that drive again.
What to Do After a Crash or Power Loss
A sudden crash or power cut can leave a few pieces half written. When you start the client again, it may show a short check on the torrents that were active. Some pieces may fail the check and download again. This is normal.
To be safe after a crash, follow these steps.
- Let the client finish its automatic checks.
- Select the torrents that were active and run Force recheck.
- Check the Execution Log for errors.
- Run a disk check if the crash happened while the drive was writing.
A laptop battery, or a small power backup for a desktop, helps avoid this problem if power cuts are common where you live.
When to Worry and When Not To
You can relax in these cases.
- The waste is under 5 percent and the torrent finished.
- The hashfails stopped after a few bad peers were banned.
- A recheck passes with all pieces good.
You should look closer in these cases.
- The waste grows on every torrent you download.
- A finished torrent fails a recheck.
- Your computer crashes, freezes, or shows errors while the failures happen.
- The failures appear after you changed hardware or memory settings.
The first group is the normal behavior of a protocol that checks everything. The second group is a message from your system that something needs attention.
Frequently Asked Questions (FAQs)
What is a hashfail in a torrent?
It is a piece that failed the hash check. The data arrived, but it did not match the code in the torrent, so the client discarded it and asked for it again.
What does wasted mean in a torrent client?
It is the data that was downloaded but not used. It includes pieces that failed the check and blocks that arrived twice.
Are hashfails bad?
A few are normal. They show that the check protected your file. Many hashfails across all torrents point to a problem with your memory, drive, or software.
How many hashfails are normal?
A small number is common. Judge by the percentage of wasted data. Under 5 percent is usually fine, and above 10 percent deserves a look.
Can hashfails damage my file?
No. Pieces that fail are discarded and never become part of the file.
Why do I see wasted data but no hashfails?
The waste comes from redundant data, such as duplicate blocks from endgame mode or slow peers.
Do hashfails slow my download?
They can, because the failed pieces must be downloaded again. A few have no noticeable effect.
How do I reduce wasted data?
Keep your computer stable, avoid editing files in the torrent folder, exclude the folder from scanners, and choose torrents with healthy swarms.
Is wasted data counted against my data cap?
Yes. Your provider counts all the traffic, including the waste.
Should I recheck a torrent with hashfails?
Yes, if the numbers are high or the torrent is stuck. A Force recheck shows whether your files are correct.
Final Thoughts
Hashfails and wasted data look scary, but they are a sign that the verification system works. Bad data is caught and replaced, and your final file stays correct.
A small amount is normal. A high number is a hint to look at the swarm, your memory, your drive, and the software that touches your files.
Read the numbers as a percentage, compare them to the piece size, and run a Force recheck when you are unsure. In most cases, there is nothing to fix.
