What Changed
Sequencing technology · AI · Benchmarking · Genomics · ComparisonModels of May 2023 to May 2026 · record to September 2026
Three years of Oxford Nanopore basecalling models, read as a record of what changed and of who measured it
Dorado v4 to v6 — What Changed, How Much, and Whether It Was Good
Between May 2023 and May 2026 Oxford Nanopore shipped five releases of DNA basecalling model for its R10.4.1 pore, from v4.2.0 to v6.0.0. Independent tests found almost every step an improvement, and the largest read-level gain measured for the super-accuracy tier came before its architecture changed. Then v6.0.0 arrived as a high-accuracy model only, with the company saying the super-accuracy tier was no longer needed. On bacterial genomes the tests published since say otherwise: sup@v5.2.0, from May 2025, remains the most accurate DNA model Oxford Nanopore ships, and the new model fails on genomes carrying two kinds of unusual DNA modification.
- 0DNA SUP models in the v6.0.0 generation — RNA has one
- ~43%fewer read errors for
sup@v5.2.0thanhac@v6.0.0, on five bacterial genomes - 13/13isolates with dnd or dpd modification systems whose HAC v6 assemblies went wrong, in a 294-isolate study
- ~1 Qby which
sup@v5.0.0overstated its own quality scores, according to Oxford Nanopore - 2.7–5.7×how much longer SUP took than HAC on the same data, in the same run
What changed, and how firmly each change is established standing first; rows are grouped by standing and never interleaved
| Standing | The change | Size |
|---|---|---|
| Documented — release record | Dorado 0.3.0 (May 2023) brought the v4.2.0 models for data sampled at 5 kHz | about 12.5 signal samples per base, up from about 10 — a change in the data, not in the model |
| Documented — release record | SUP became a transformer at v5.0.0 (Dorado 0.7.0, May 2024); HAC stayed recurrent | sup@v5.2.0 has 78,718,162 parameters, hac@v5.2.0 8,790,768 — 8.95× |
| Documented — release record | Dorado 1.0.0 (May 2025) dropped the models for the older R9.4.1 pore, for 4 kHz data and for RNA002, and Fast5 input | still available in Dorado 0.9.6 |
| Documented — release record | v6.0.0 (Dorado 2.0.0, May 2026) is a HAC model only for DNA; RNA got fast, HAC and SUP | no DNA SUP or fast v6 in the model list as of September 2026 |
| Peer-reviewed measurement | SUP v4.3 against v5.0, the same raw data from 80 bacterial isolates | average cgMLST allele distance 4.53 → 0.76 unpolished, 1.78 → 0.04 with the same polishing |
| Preprint, not yet peer-reviewed | HAC v6 against SUP v5.2 on 294 isolates of ten foodborne pathogens | near-identical cgMLST for 93.5% against 97.3%; all 13 isolates with dnd or dpd systems went wrong with HAC v6 |
| Independent test | sup@v4.2.0 → sup@v4.3.0 | median read Q18.5 → Q20.5, about a third fewer read errors; assembly errors across nine genomes 173 → 37 |
| Independent test | hac@v5.0.0 → hac@v5.2.0 | median read Q16.3 → Q17.0, about 15% fewer read errors; median assembly errors 37.5 → 13 |
| Independent test | sup@v5.0.0 → sup@v5.2.0 | read accuracy essentially flat; median assembly errors 3 → 3, mean assembly accuracy Q60.4 → Q61.6 |
| Independent test | hac@v5.2.0 → hac@v6.0.0 | median read Q17.2 → Q18.1, about 19% fewer read errors; median assembly errors 25.5 → 11 |
| Vendor statement, consistent with the tests | sup@v5.0.0 quality scores ran about one Q point high; v5.2 reads are “just as accurate” | why the same reads score lower under v5.2.0 while measured accuracy stays flat |
| Vendor claim, not like-for-like | v5 SUP reaches Q26, 99.75% raw-read accuracy | a modal figure on human HG002 data; the independent figures here are medians on bacteria |
| Vendor claim, not like-for-like | HAC v6 reaches single-molecule accuracy of Q23.5 | independently, a median of Q18.1 and a peak near Q19.7 on bacterial isolates |
| Vendor claim, not borne out | A SUP tier is “no longer needed” | sup@v5.2.0 still has about 43% fewer read errors, and about a third of the median assembly errors — 4 against 11 |
| Vendor claim, not borne out | HAC v6 gives polished bacterial assemblies comparable to SUP v5.2 | polishing narrowed the gap and did not close it |
| Vendor claim, not borne out | HAC v6 modified-base calling outperforms SUP “on every single model” | on five bacterial genomes no model was best on every measure, and hac@v6.0.0 did not always beat hac@v5.2.0 |
In What Order
The order it happened in releases are dated by Dorado’s own release notes and measurements by publication; the v3.x models, for the older R9.4.1 pore, sit outside every comparison here and are not dated
- 18 May 2023Dorado 0.3.0 ships the v4.2.0 models for 5 kHz data.
- 24 Oct 2023Ryan Wick tests the v4.2.0 fast, HAC and SUP models and a research model fine-tuned for native bacterial DNA, on nine bacterial genomes. The research model edges out SUP.
- 5 Dec 2023Dorado 0.5.0 ships v4.3. On 18 December Wick measures SUP at a median Q20.5, up from Q18.5, and assembly errors across the nine genomes down from 173 to 37; he reports that the bacterial training of the research model has been folded in.
- 21 May 2024Dorado 0.7.0 ships v5: SUP moves from LSTM to a transformer, HAC stays LSTM. At London Calling, Oxford Nanopore puts v5 SUP at Q26, 99.75%.
- 21 Jan 2025Dorado 0.9.1 speeds up basecalling. One laboratory’s SUP v5.0 rebasecall of a single run drops from 46.3 hours to 18.7.
- 21 May 2025Dorado 1.0.0 ships v5.2: HAC grows from five LSTM layers to seven; SUP keeps its architecture and changes its weights. The R9.4.1, 4 kHz and RNA002 models and Fast5 input are dropped.
- 27 May 2025Wick: HAC has about 15% fewer read errors and 65% fewer median assembly errors; SUP reads are essentially unchanged.
- 13 Jun 2025Prior and colleagues, in the Journal of Clinical Microbiology: on 80 isolates, SUP v5.0 brings cgMLST typing close to Illumina, where v4.3 was sometimes insufficient.
- 27 Jan – 26 Feb 2026A user reports on Dorado’s issue tracker that the same reads score lower under
sup@v5.2.0. On 16 February Oxford Nanopore answers that v5.0.0 overstated its scores by about one Q point. - 18 Mar 2026Oxford Nanopore’s blog explains the transformer SUP and says it kept the LSTM’s inference-compute budget.
- 24 Mar 2026Biggel and colleagues post a preprint testing SUP v5.2 on 294 foodborne-pathogen isolates.
- 20 May 2026Dorado 2.0.0 ships v6.0: for DNA, a HAC model with custom recurrent layers and no SUP. Mike Vella, Oxford Nanopore’s VP of Machine Learning, at London Calling: “Importantly, we’re not releasing a sup model this time… we believe that this particular model is good enough that a sup tier is no longer needed.”
- 11 Jun 2026Wick:
hac@v6.0.0has about 19% fewer read errors thanhac@v5.2.0, butsup@v5.2.0is still about 43% ahead; one Klebsiella genome produces about 100 errors per assembly with v6. - 19 Jun 2026Wick polishes the assemblies: the gap narrows and does not close. Vella suggests to him that phosphorothioate backbone modifications, absent from training, cause the Klebsiella errors.
- 6 Jul 2026The preprint’s second version adds HAC v6: every one of 13 isolates carrying dnd or dpd DNA-modification systems gives a highly inaccurate assembly.
- 8–9 Jul 2026Wick’s methylation test finds no model best on every measure. The next day he attributes the Klebsiella errors to 7-deazaguanine modifications from a dpd system, citing Biggel’s preprint.
- 13 Jul 2026Dorado 2.1.0 speeds up v6.0.0 HAC on Blackwell GPUs, and v5.0.0-onward SUP on short reads.
- 15 Jul 2026Kulkarni and colleagues, in Nature Communications: the older v4 model remains the reliable choice for CpG methylation, while newer models are better for other modifications.
Put in order of date, the biggest event here is v5.0.0, when the super-accuracy model became a transformer. Put in order of evidence, it is one of the least measured. Wick’s independent series tests v4.2.0 against v4.3.0, and then v5.0.0 against v5.2.0; it never sets sup@v4.3.0 against sup@v5.0.0 read by read. What measures that step independently is the cgMLST study of Prior and colleagues, which basecalled the same raw data from 80 isolates both ways.
Its result is strong and it is a different kind of evidence. Unpolished, the average allele distance to the true genome fell from 4.53 to 0.76; with the same polishing, from 1.78 to 0.04. That is consensus accuracy, which is what most laboratories use. The per-read figure a model version is advertised on, Q26, rests on Oxford Nanopore’s own modal measurement on human data.
- 4.53 → 0.76average cgMLST allele distance, SUP v4.3 against v5.0 on the same raw data, before any polishing
- Q26Oxford Nanopore’s v5 SUP figure: modal, on human HG002 data
The Argument
Two cases about the same model Oxford Nanopore’s for HAC v6, and Ryan Wick’s against dropping SUP; both are published, and both are named here
Oxford Nanopore’s case is about a trade-off. A more accurate basecaller has usually meant a bigger model, and a bigger model means more computers, slower runs and more latency. With HAC v6, Mike Vella told London Calling, “we break that trade-off”, through neural-network layers designed in-house and low-level optimisation of Dorado. From there the company made three specific claims: bacterial assemblies comparable to SUP after polishing, modified-base calling that beats SUP on every model, and a model good enough that a SUP tier is no longer needed. It released the model on GitHub first, it said, so that early adopters could test it before it reached the instrument software.
Wick’s case is that, on bacterial isolates, the measurements do not support the last of those. Over three posts he found sup@v5.2.0 better at the read level and the assembly level, polishing narrowing the gap without closing it, and methylation results with no single winner. His plea is direct: “do not abandon sup basecalling”. He and many collaborators in microbial genomics, he writes, run SUP, having the compute to do it in real time. Two things in his account are his own reading and are offered as such: that HAC v6 was probably developed with human sequencing in mind, and that accuracy for bacterial genomes has largely plateaued.
- 3specific Oxford Nanopore claims for HAC v6 that independent bacterial tests have checked
- 5bacterial genomes in Wick’s 2026 tests — one species each
Case 1
Oxford Nanopore: HAC v6 makes SUP unnecessary
- Custom recurrent layers keep the model close to the old HAC’s size: 9,808,240 parameters against 8,790,768.
- Claimed: polished bacterial assemblies comparable to SUP v5.2, and assemblies above Q60 after polishing.
- Claimed: better short-tandem-repeat calls, and the most accurate modified-base calling Oxford Nanopore has produced.
Case 2
Wick: on bacteria, SUP is still the better model
- Median read accuracy Q20.6 for
sup@v5.2.0against Q18.1 forhac@v6.0.0. - Median errors per assembly 4 against 11, and polishing does not close the gap.
- Methylation: no model best on every measure; for some 5mC work
hac@v5.2.0may be the right choice.
- Median read accuracy Q20.6 for
Common ground
What neither side disputes
hac@v6.0.0is the most accurate HAC model yet, and in Wick’s run slightly faster thanhac@v5.2.0.- SUP costs several times HAC’s compute; HAC is the tier that keeps up with a fully loaded PromethION.
- Whether a DNA SUP v6 will ever ship is not stated by either.
What Others Add
The measurements, side by side each row is one post’s own comparison; posts ran on different Dorado versions and depths, so rows are not chained
| Comparison | Median read accuracy | Fewer read errors | Assembly errors | Tested |
|---|---|---|---|---|
| SUP v4.2.0 → v4.3.0 | Q18.5 → Q20.5 | about a third | 173 → 37 in total, nine genomes | Dec 2023 |
| HAC v5.0.0 → v5.2.0 | Q16.3 → Q17.0 | ~15% | median 37.5 → 13 | May 2025 |
| SUP v5.0.0 → v5.2.0 | essentially unchanged | — | median 3 → 3 | May 2025 |
| HAC v5.2.0 → v6.0.0 | Q17.2 → Q18.1 | ~19% | median 25.5 → 11 | Jun 2026 |
sup@v5.2.0 against hac@v6.0.0 | Q20.6 against Q18.1 | ~43% | median 4 against 11 | Jun 2026 |
| Same run, same data | HAC | SUP | SUP takes |
|---|---|---|---|
| Dorado 1.0.0, no modified bases | hac@v5.2.0 3h18m | sup@v5.2.0 18h45m | 5.7× |
| Dorado 2.0.0, modified bases on | hac@v5.2.0 8h04m | sup@v5.2.0 21h33m | 2.7× |
| Dorado 2.0.0, modified bases on | hac@v6.0.0 7h48m | sup@v5.2.0 21h33m | 2.8× |
SUP has 8.95 times HAC’s parameters, but in the same run it took 2.7 to 5.7 times as long; the parameter ratio is not the time ratio. All of Wick’s timings come from a shared node on a university cluster, which he says makes them imprecise, so the only ratios worth quoting are those taken within one run.
Two other figures about speed point different ways and are both on the record. Oxford Nanopore’s blog says the transformer SUP kept the LSTM’s inference-compute budget; Prior and colleagues found SUP v5.0 basecalling took two to three times as long as v4.3 on their equipment, before Dorado 0.9.1 cut one of their runs from 46.3 hours to 18.7. And sup@v5.2.0 ran about 33% faster than sup@v5.0.0 at an identical parameter count, but on a newer Dorado release, and Wick could not say whether the software or the load on the cluster was the cause.
- 8.95×SUP’s parameters against HAC’s, v5.2.0
- 2.7–5.7×SUP’s time against HAC’s, within one run
Quality scores
A lower score is not a worse read
- Under
sup@v5.2.0, 62.5% fewer of them passed Q20 than undersup@v5.0.0, and 17.8% fewer passed Q15; lengths and base counts barely moved. - Oxford Nanopore’s answer: v5.0.0 scores ran about one Q point above the reads’ true accuracy, and v5.2 fixed the calibration.
- Measured by alignment, SUP read accuracy did not change between the two, which fits that answer.
- Under
Atypical modifications
What HAC v6 was not trained on
- Isolates carrying dnd (phosphorothioation) or dpd (7-deazaguanine) systems: all 13 went wrong with HAC v6, with 24 to 314 mismatching alleles, median 78.
- SUP v5.2 is not immune: it failed on four Salmonella Kentucky isolates with a dnd system, at 20 to 68 mismatching alleles.
- In public genomes, dnd turns up in 44 of 67 pathogen species and dpd in up to 8% of several Klebsiella, Escherichia and Enterobacter species.
Methylation
Modified bases do not follow the version order
- For CpG methylation the older v4 5mCG model is the most reliable; the v5.2 5mCG model misses methylated CpGs surrounded by other CG residues.
- Newer v5 models are clearly better for 5mC outside CpG, for 4mC and for 6mA.
- For CpG, HAC performs almost exactly as SUP does; for 6mA and 4mC, SUP is consistently better.
Vendor and independent figures describe different things, and neither is wrong for that. Oxford Nanopore’s accuracy figure is the modal raw-read accuracy on human HG002 data; Wick reports medians on bacterial isolates, with every read included. Nanopore read accuracy is bimodal — a small peak around Q5 to Q10 and the main peak above Q15 — so mode, median and mean genuinely differ, and a read-quality filter moves all three. Wick’s own mode for hac@v6.0.0, near Q19.7, sits closer to its median of Q18.1 than to the Q23.5 shown for it at London Calling.
- Q23.5shown for HAC v6 at London Calling 2026
- Q19.7the peak of HAC v6 read accuracy on five bacterial genomes
Was It Good
Which model for which need a comparison of models ends in fit, not in a winner: each card says who it suits, what it is best at, and what it costs
sup@v5.2.0For bacterial assembly and typing, where the GPU allows
- The best result on every independent bacterial test here: reads, assemblies and polished assemblies.
- Near-identical cgMLST profiles for 97.3% of 294 foodborne-pathogen isolates at 50× coverage.
- The cost: 2.7 to 5.7 times HAC’s basecalling time — and it still fails on some genomes carrying dnd systems.
hac@v6.0.0For high-volume, compute-bound and real-time work
- About 19% fewer read errors than
hac@v5.2.0, at slightly higher speed. - The tier Oxford Nanopore recommends for most users, and the one that keeps pace with a fully loaded PromethION.
- The cost: it fails on genomes carrying dnd or dpd systems — 13 of 13 in one study. A reference-free check such as alpaqa flags affected assemblies.
- About 19% fewer read errors than
v4 5mCG model
For CpG methylation
- The most reliable model for CpG sites in an independent benchmark across bacteria, plants, mouse and human.
- HAC performs almost exactly as SUP does for CpG, so the cheaper tier suffices.
- The cost: a modification model is paired with its own basecalling model, so this choice ties the CpG calls to a v4 basecall.
v5 modification models
For 6mA, 4mC and 5mC outside CpG
- Clearly better than the v4 models for these marks.
- SUP is consistently better than HAC for 6mA and 4mC.
- The cost: on bacteria no v5.2 or v6 model was best on every measure, and for some 5mC work
hac@v5.2.0had the best recall.
- Re-examine any quality-score filter after changing model. On identical reads,
sup@v5.2.0put 62.5% fewer over Q20 thansup@v5.0.0— a recalibration, not lost accuracy. Check aligned accuracy, not the score. - Test a new model on your own data before switching. One SUP release brought no read-level gain, and the newest HAC fails on a whole class of genomes.
- Polish bacterial assemblies with the bacterial model. In Wick’s tests the older pileup bacterial model made 6 of 147 assemblies worse, against 22 and 14 for the two read-level models, and improved the most.
- Compare studies within one pore. Models are trained for one sequencing condition each, so R9.4.1 data needs an R9.4.1 model — and Dorado 0.9.6 is the last release that carries them.
What to hold loosely
Nearly every cross-version read and assembly figure here comes from one independent tester, on five to nine bacterial genomes, one per species; human, metagenomic and RNA results may differ, and Wick himself suspects HAC v6 would look better on human data. His timings come from a shared cluster node. Oxford Nanopore’s figures and his are modal against median, on human against bacterial data, so the gap between them is not by itself evidence that either is wrong. The 294-isolate study is a preprint, not yet peer-reviewed. And whether a DNA SUP v6 will ever ship is unknown: the company said only that it is not releasing one “this time”.
What would change the answer
A released DNA sup@v6.0.0; an independent test showing HAC v6 matching SUP on bacterial assemblies; or a HAC model trained on dnd and dpd modifications. Until one of those, the most accurate DNA model Oxford Nanopore ships dates from May 2025.
What could not be verified
Unconfirmed report — Clive Brown of Oxford Nanopore, at London Calling 2024 as quoted by Bio-IT World: that Q30 simplex accuracy was available at the cost of about 15% of yield and a basecaller four times slower. No model or setting for such a mode appears in Dorado’s release notes or model list.
Unconfirmed report — Mike Vella of Oxford Nanopore, as relayed by Wick in June 2026: that the company was working on an updated polishing model to correct errors linked to phosphorothioate modifications. The one Dorado release since lists no new polishing model.
Take-home and sources
- Ryan Wick, Ryan Wick’s bioinformatics blog — six posts, October 2023 to July 2026
- Oxford Nanopore Technologies — Dorado release notes, model list and model documentation, a London Calling 2024 news release, its accuracy page, a March 2026 blog post and the London Calling 2026 technology talk
- Allison Proffitt, Bio-IT World (2024)
- Dorado GitHub issue #1565 (2026)
- Prior et al., Journal of Clinical Microbiology (2025)
- Biggel et al., bioRxiv preprint (2026)
- Kulkarni et al., Nature Communications (2026). Percentages were recomputed from the published Q values and timings, with error rate
10^(−Q/10).
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