Q‑Day.org exists to cut through the hype around “Q‑Day” – the moment quantum computers can break today’s public‑key cryptography.

I’m Marin Ivezic, founder of Applied Quantum and a longtime writer at PostQuantum.com. Seeing how much noise distorts timelines, I built this site to share a transparent, model‑driven way to forecast the quantum risk. You’ll find a curated set of my most relevant articles from PostQuantum.com, a plain‑English walkthrough of the assumptions behind my own forecast, and a simple Q‑Day Estimator that lets you adjust the key parameters and generate your own timeline. The goal isn’t to hand you a date; it’s to equip you with a method you can stress‑test and refine.

Make Your Own Q-Day Prediction

These resources give you the tools to understand quantum computing progress and estimate when cryptographically relevant quantum computers (CRQCs) will arrive.

How the Methodology Works

The prediction framework has three layers that build on each other: Eight Capabilities → Three Levers → One Benchmark Score → Timeline Prediction

1. The full methodology The Path to CRQC – A Capability‑Driven Method for Predicting Q‑Day identifies eight fundamental capabilities needed to break RSA-2048 encryption

2. These combine into three key levers that capture what matters most:
– LQC (Logical Qubit Capacity): How many error-corrected qubits are available
– LOB (Logical Operations Budget): How many quantum gates can run reliably in sequence
– QOT (Quantum Operations Throughput): How many operations per second the system achieves

3. The CRQC Readiness Benchmark – Benchmarking Quantum Computers on the Path to Breaking RSA-2048 explains these three levers and combines them into a single score showing current progress toward RSA-2048 breaking capability (currently ~0.05%). Simplified how-to How You, Too, Can Predict Q-Day (Without the Hype) shows you how to use those three levers.

4. The CRQC Readiness Benchmark (Q-Day Estimator) Tool helps you tweak your own parameters and assumptions to come up with your own current capability scope (the CRQC Benchmark). It then takes that current capability score plus an annual growth factor to project when we’ll reach 100% (Q-Day)

5. The Quantum Computing Roadmaps track all main quantum hardware companies, assessing them on track record – have they consistently hit past milestones? This separates credible roadmaps from marketing hype, helping you weight vendor predictions appropriately. It gives you a reality check: who’s actually delivering and how close to your prediction are their roadmaps?

How They Work Together? Learn the framework → See where we are today → Project your own timeline → Validate against real progress

Why This Matters to You

The current consensus points to 2030 ±2 years for CRQC capability. But rather than trusting any single prediction (including mine), these resources empower you to:

– Evaluate vendor announcements critically
– Adjust timelines as technology advances
– Make informed decisions about post-quantum cryptography migration
– Explain quantum threats to leadership with data-backed reasoning

Your organization’s cryptographic migration timeline is 5-10+ years. Understanding when quantum computers become cryptographically relevant isn’t just academic – it helps you with the risk exposure prediction.

CRQC Quantum RSA-2048

The Path to CRQC – A Capability‑Driven Method for Predicting Q‑Day

This guide is the most detailed, end‑to‑end map I know of for understanding what it will actually take to reach a cryptographically relevant quantum computer (CRQC), i.e. break RSA-2048 - not just headline qubit counts. It breaks the problem into the capabilities that determine CRQC feasibility and timing, shows their interdependencies, and anchors each one in observable metrics, current status, gaps, and TRLs. If you’re trying to forecast Q‑Day with rigor (or defend against it), ...
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CRQC Readiness Benchmark

CRQC Readiness Benchmark – Benchmarking Quantum Computers on the Path to Breaking RSA-2048

Benchmarking quantum capabilities for cryptography is both critical and challenging. We can’t rely on any single metric like qubit count to tell us how near we are to breaking RSA-2048. A combination of logical qubit count, error-corrected circuit depth, and operational speed must reach certain thresholds in unison. Existing benchmarks – Quantum Volume, Algorithmic Qubits, etc. – each address parts of this, but a CRQC-specific yardstick brings them together. By focusing on a concrete goal ...
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How to estimate q-day

How You, Too, Can Predict Q-Day (Without the Hype)

For three decades, Q-Day has been “just a few years away.” I want to show you how to make your own informed prediction on when Q-Day will arrive. Counting physical qubits by itself is misleading. To break RSA you need error‑corrected logical qubits, long and reliable operation depth, and enough throughput to finish within an attack‑relevant time window ...
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Do Your Own Prediction

Read about the approach and relevant attributes in the two articles above. Then use the CRQC Readiness Benchmark (Q‑Day Estimator) tool below to turn assumptions into a defensible, crypto‑specific forecast. The tool converts four inputs, LQC (logical qubits), LOB (logical operations budget), QOT (logical ops/sec), and an annual growth factor, into a Composite CRQC Readiness Score and a projected “Q‑Day” (when week‑scale factoring of RSA‑2048 becomes practical). Start with Conservative / Median / Aggressive presets, then tweak to match vendor claims or your own view of roadmaps and error‑correction progress. This is intentionally focused on cryptographic breakability, not generic “quantum advantage,” so it may diverge from headline qubit counts.

For readers who want the most detailed, capability‑driven approach to forecasting Q‑Day, see my full methodology article article Path to CRQC – A Capability‑Driven Method for Predicting Q‑Day. It maps the eight technical capabilities behind CRQC, their interdependencies, and TRLs. By design, the Q‑Day Estimator and its methodology presented here are simpler and immediately usable: they compress those capabilities into three executive levers – Logical Qubit Capacity (LQC), Logical Operations Budget (LOB), and Quantum Operations Throughput (QOT) – so non‑expert users can track tangible milestones and run scenario analyses without wading through the full stack.

Another useful signal I track is vendor execution: announcements and public roadmaps from quantum hardware manufacturers, weighted by their historical hit‑rate on milestones teams that consistently deliver earn more credibility on future targets, and their claims map more directly to LQC/LOB/QOT in the estimator. See the list here: Quantum Hardware Companies and Roadmaps Comparison (2025 Edition).
[Disclaimer: this estimator is for education and scenario exploration only – it is not a prediction, guarantee, or formal risk assessment, and it should not be relied on for policy, compliance, investment, or procurement decisions. Methodology and assumptions used for this estimator: “CRQC Readiness Benchmark – Benchmarking Quantum Computers on the Path to Breaking RSA-2048.”]

CRQC Readiness Benchmark (Q-Day Estimator)

An interactive way to explore how close we may be to a cryptographically relevant quantum computer (CRQC) for breaking RSA-2048. Adjust assumptions below to see how the projected Q‑Day shifts. Methodology & discussion. Disclaimer: this tool is for experimentation and scenario analysis only.

Scenarios: Load a starting scenario, then tweak parameters to explore.
Count of error-corrected (logical) qubits available.
x
Reliable logical operations available (circuit depth).
x
Logical operations per second (throughput).
Annual capability multiplier for the composite score.
Advanced formula (optional)
Composite CRQC Readiness Score
0.00
Projected Q-Day
—
Projected CRQC Readiness score over time
Score 1.0 ≈ quantum capability to factor RSA-2048 in about one week. Adjust inputs and formula to explore scenarios. Estimates are illustrative only.

All Q-Day Related Articles from PostQuantum.com

Countdown to my predicted Q-Day

 

A series of breakthroughs, from improved quantum computing algorithms to enhanced error correction and quantum hardware scaling, signals a shift in the quantum computing landscape. In my opinion. These developments indicate that quantum supremacy and cryptographically relevant quantum computing (CRQC) are transitioning from primarily scientific challenges to practical engineering problems. I track all significant research papers and engineering milestones that inform my prediction in a timeline listed here:

Marin’s Q-Day Prediction – Timeline