The blockchain scalability trilemma is the observation, popularised by Ethereum co-founder Vitalik Buterin, that a blockchain built with simple techniques can achieve only two of three properties at once: scalability, decentralisation and security. Raising throughput usually means bigger blocks or fewer validators, which makes nodes costlier to run and concentrates control.
What are the three properties in the trilemma?
Buterin defines the three properties precisely in his 2021 essay on sharding:
- Scalability: the chain "can process more transactions than a single regular node (think: a consumer laptop) can verify."
- Decentralisation: the chain "can run without any trust dependencies on a small group of large centralized actors."
- Security: the chain "can resist a large percentage of participating nodes trying to attack it."
The definitions matter. Scalability here does not just mean "fast"; it means handling more activity than one ordinary computer could check by itself, without asking users to trust whoever owns the bigger machines.
Why can't a blockchain simply have all three?
In a traditional blockchain, every full node downloads and re-executes every transaction, so throughput is capped by what an ordinary node can handle. There are three obvious ways to push past that cap, and each gives something up:
- Bigger or faster blocks raise hardware and bandwidth requirements, so fewer people can run nodes. Decentralisation falls.
- A small set of powerful validators can process more, but users must trust that group. Decentralisation falls.
- Many separate chains spread the load, but each is secured by only a fraction of the validators, so attacking one is cheaper. Security falls.
The Bank for International Settlements reached a similar conclusion in 2022, writing that permissionless blockchains "can achieve only two of three properties" and pointing to congestion and high fees as the visible symptom.
How do real blockchains trade off the three?
| Network or design | Leans towards | How | Trade-off |
|---|---|---|---|
| Bitcoin | Decentralisation and security | Blocks about every 10 minutes with a capped block size | Limited base-layer throughput; payments scaled through layers such as Lightning |
| Ethereum (Layer 1) | Decentralisation and security | 12-second slots; anyone with 32 ETH can run a validator | Base-layer capacity kept modest; most scaling moved to rollups |
| BNB Smart Chain | Scalability and security | 0.45-second blocks; 45 active validators chosen by stake (PoSA) | Far fewer block producers than Bitcoin or Ethereum |
| DPoS chains such as TRON | Scalability and security | 27 elected Super Representatives produce 3-second blocks | Small producer set and concentrated voting power |
| Many independent chains | Scalability and decentralisation | Activity spread across chains, each with its own validators | Each chain is only as secure as its own validator set |
These rows match the three groups Buterin describes: traditional blockchains that are decentralised and secure but not scalable, high-throughput chains that rely on a small set of nodes, and multi-chain ecosystems where each chain is easier to attack.
How are developers trying to solve the trilemma?
Ethereum's answer is a modular, rollup-centric design. The base layer stays relatively small and decentralised, while Layer 2 networks that settle on Layer 1 execute most transactions and post compressed data back to it. Recent upgrades expand the data space rollups use:
- Dencun (13 March 2024) introduced "blobs" (EIP-4844), a cheaper data space for rollups that is deleted after about 18 days.
- Pectra (7 May 2025) raised the blob target from three to six per block and the maximum from six to nine, according to ethereum.org.
- Fusaka (3 December 2025) added PeerDAS, which lets each node hold about one-eighth of the blob data and verify the rest by sampling, allowing up to eight times more blob capacity in theory.
- Bitcoin scales payments off-chain through payment channels such as the Lightning Network.
Buterin argues that sharding combined with data availability sampling "gets you all three." For the different approaches in use today, see types of layer 2 solutions.
Is the trilemma a law or a rule of thumb?
It is a rule of thumb, not a mathematical proof. Buterin's own framing is that the trade-off binds when you stick to simple techniques. Rollups and data sampling relax it, but introduce new trust assumptions: many Layer 2 networks still rely on a single sequencer and upgradeable contracts, which L2BEAT's stages framework tracks network by network.
When a project claims to have "solved" the trilemma, ask which of the three properties it measured, and how. Our guide to blockchain limitations covers other constraints, and decentralisation explained shows how to check the decentralisation side of the claim.
Where Wealtii's funds sit on the trilemma: Wealtii's funds run on BNB Smart Chain, which leans towards throughput and low fees (network gas fees are typically under $0.50) at the cost of a smaller validator set than Ethereum's. Learn more in what BNB Smart Chain is, or see every cost on Wealtii's fees page.
Frequently Asked Questions
What is the blockchain trilemma?
The blockchain trilemma, or scalability trilemma, says that a blockchain built with simple techniques can achieve only two of three properties at once: scalability, decentralisation and security.
Who came up with the scalability trilemma?
The idea was popularised by Ethereum co-founder Vitalik Buterin, who set out precise definitions of the three properties in a 2021 essay on sharding. The Bank for International Settlements used the same framing in its 2022 annual report.
Has any blockchain solved the trilemma?
No network has clearly solved it. Ethereum is pursuing rollups and data availability sampling to scale without giving up decentralisation, while faster chains such as BNB Smart Chain accept smaller validator sets. Each approach makes different trade-offs.
How do Layer 2 networks help with the trilemma?
Layer 2 rollups execute transactions off the main chain and post compressed data or proofs back to it, so the base layer can stay decentralised and secure while total throughput grows. They add their own risks, such as centralised sequencers.
Sources & References
- Buterin, V. (2021) — Why sharding is great: demystifying the technical properties (accessed 21 Oct 2026)
- Bank for International Settlements — Annual Economic Report 2022, chapter III (accessed 21 Oct 2026)
- ethereum.org — Danksharding and proto-danksharding (EIP-4844) (accessed 21 Oct 2026)
- ethereum.org — Fusaka upgrade (PeerDAS) (accessed 21 Oct 2026)
- BNB Chain Docs — BNB Smart Chain introduction (accessed 21 Oct 2026)
Disclaimer: This content is for educational purposes only and does not constitute financial, tax, or legal advice. Digital assets are volatile and carry risk of loss. Wealtii is early-stage and is not regulated by any financial authority.
