The Local Distance Network: A community consensus report on the measurement of the Hubble constant at ∼1% precision

¹ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
² Institute of Physics, École Polytechnique Fédérale de Lausanne (EPFL), Observatoire de Sauverny, 1290 Versoix, Switzerland
³ Inter-University Centre for Astronomy and Astrophysics (IUCAA), Post Bag 4, Ganeshkhind, Pune 411 007, India
⁴ NSF NOIRLab, 950 N Cherry Ave, Tucson, AZ 85719, USA
⁵ Research School of Astronomy & Astrophysics, Australian National University, Cotter Road, Weston Creek, ACT 2611, Australia
⁶ European Space Agency (ESA), ESA Office, Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
⁷ Boston University Departments of Astronomy and Physics, 725 Commonwealth Ave, Boston, USA
⁸ INAF – Astronomical Observatory of Abruzzo, Via Maggini, 64100 Teramo, Italy
⁹ Max-Planck-Institute for Astrophysics, Karl-Schwarzschild-Str. 1, 85741 Garching, Germany
¹⁰ Sorbonne Université, CNRS, Laboratoire de Physique Nucléaire et de Hautes Energies, 75252 Paris, France
¹¹ School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK
¹² School of Mathematical and Physical Sciences, University of Sheffield, Hounsfield Road, Sheffield S3 7RH, United Kingdom
¹³ Institute of Space Sciences (ICE-CSIC), Campus UAB, Carrer de Can Magrans, s/n, E-08193 Barcelona, Spain
¹⁴ Institut d’Estudis Espacials de Catalunya (IEEC), 08860 Castelldefels, Barcelona, Spain
¹⁵ Institut de Ciéncies del Cosmos (ICCUB), Universitat de Barcelona (UB), c. Martí i Franquès, 1, 08028 Barcelona, Spain
¹⁶ Departament de Física Quàntica i Astrofísica, Universitat de Barcelona, Martí i Franquès 1, E08028 Barcelona, Spain
¹⁷ Polish Academy of Sciences, Nicolaus Copernicus Astronomical Center, Department of Astrophysics, ul. Rabiańska 8, 87-100 Toruń, Poland
¹⁸ Center for Astrophysics | Harvard & Smithsonian, 60 Garden Street, Cambridge, MA 02138, USA
¹⁹ Department of Physics, Utah Valley University, 800 West University Parkway, Orem, UT 84058, USA
²⁰ LIRA, Observatoire de Paris, Université PSL, Sorbonne Université, Université Paris Cité, CY Cergy Paris Université, CNRS, 92190 Meudon, France
²¹ French-Chilean Laboratory for Astronomy, IRL 3386, CNRS and U. de Chile, Casilla 36-D, Santiago, Chile
²² European Southern Observatory, Karl-Schwarzschild-Strasse 2, 85748 Garching, Germany
²³ Department of Physics & Astronomy, Johns Hopkins University, Baltimore, MD 21218, USA
²⁴ Department of Astronomy, University of California, Berkeley, CA, USA
²⁵ Department of Physics & Astronomy, College of Sciences, University of Texas Rio Grande Valley, 1201 W University Blvd, Edinburg, TX 78539, USA
²⁶ Black Hole Initiative at Harvard University, 20 Garden Street, Cambridge, MA 02138, USA
²⁷ School of Mathematics and Physics, University of Queensland, Brisbane, QLD 4072, Australia
²⁸ University Observatory, Faculty of Physics, Ludwig-Maximilians-Universität, Scheinerstr. 1, 81677 Munich, Germany
²⁹ Excellence Cluster ORIGINS, Boltzmannstr. 2, 85748 Garching, Germany
³⁰ Department of Physics, Duke University, Durham, NC 27708, USA
³¹ Scuola Superiore Meridionale, Largo S. Marcellino 10, 80138 Napoli, Italy
³² INAF-Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Napoli, Italy
³³ Astronomical Observatory, University of Warsaw, Al. Ujazdowskie 4, 00-478 Warszawa, Poland
³⁴ American Public University System, 111 W. Congress St., Charles Town, WV 25414, USA
³⁵ Center for Astronomy, Space Science and Astrophysics, Independent University, Bangladesh, Dhaka 1245, Bangladesh
³⁶ Institució Catalana de Recerca i Estudis Avançats, Passeig de Lluís Companys, 23, 08010 Barcelona, Spain
³⁷ International Space Science Institute, Hallerstrasse 6, 3012 Bern, Switzerland

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Received: 5 November 2025
Accepted: 2 December 2025

Abstract

Context. The direct empirical determination of the local value of the Hubble constant (H₀) has markedly advanced thanks to improved instrumentation, measurement techniques, and distance estimators. However, combining determinations from different estimators is nontrivial due to their correlated calibrations and different analysis methodologies.

Aims. Using covariance weighting and leveraging community expertise, we have constructed a rigorous and transparent “Distance Network” to find a consensus value and uncertainty for the locally measured Hubble constant.

Methods. Experts across all relevant distance measurement domains were invited to critically review the available datasets spanning parallaxes, detached eclipsing binaries, masers, Cepheids, the tip of the red giant branch, Miras, carbon-rich asymptotic giant branch stars, Type Ia (SNe Ia) and Type II supernovae, surface brightness fluctuations, the fundamental plane, and Tully–Fisher relations. Before any calculations, the group voted for first-rank indicators to define a “baseline” Distance Network. Other indicators were included to assess the robustness and sensitivity of the results. We provide open-source software and data products to support full transparency and future extensions of this effort.

Results. Our key findings are as follows: (1) The local H₀ is robustly determined, with first-rank indicators internally consistent within their uncertainties. (2) A covariance-weighted combination yields a relative uncertainty of 1.1% (baseline) or 0.9% (all estimators). (3) The contribution from SNe Ia is consistent across compilations of optical or NIR magnitudes. (4) Removing either Cepheids or the tip of the red giant branch has a minimal effect on the central value of H₀. (5) Replacing SNe Ia with galaxy-based indicators changes H₀ by less than 0.1 km s⁻¹ Mpc⁻¹ while doubling its uncertainty. (6) The baseline result is H₀ = 73.50 ± 0.81 km s⁻¹ Mpc⁻¹, 7.1σ from the early Universe plus ΛCDM result 67.24 ± 0.35 km s⁻¹ Mpc⁻¹ and 5.0σ from BBN+BAO within a flat ΛCDM DESI DR2 (68.51 ± 0.58 km s⁻¹ Mpc⁻¹).

Conclusions. A networked approach, such as the one presented here, is invaluable for enabling further progress in Hubble constant measurements, as it provides the much needed advances in accuracy and precision without overreliance on any single method, sample, or group.