Blockchain Technology
ByAUJay
Sidechains vs Rollups: Ethereum.org’s Take and a Real Throughput–Cost Comparison
Summary: Decision-makers don’t need a generic primer—they need the most current, quantitative picture. This post distills Ethereum.org’s definitions, then compares today’s real-world throughput, fees, and security trade-offs across rollups and sidechains, with practical benchmarks and implementation checklists.
TL;DR for CTOs and product leaders
- Rollups inherit Ethereum security and now post data into “blobs” (EIP‑4844), pushing typical L2 user fees into low‑cent ranges; throughput is ultimately limited by L1 data bandwidth and a project’s compression/prover pipeline. (ethereum.org)
- Sidechains run their own consensus. They routinely deliver higher raw TPS and sub‑cent fees but carry independent validator/bridge risk; choose only when that trust model is acceptable. (ethereum.org)
- Snapshot of costs (Jan 2026): ETH transfers on major rollups range roughly $0.04–$0.19; token swaps often $0.18–$0.57. Large sidechains show $0.002–$0.03 typical medians, with some pushing ~$0.001. (l2fees.info)
- Governance maturity matters: Several leading optimistic stacks have activated permissionless fault/fraud proofs, materially reducing trust in operators; use L2BEAT’s Stages and DA-risk frameworks to assess decentralization and DA assumptions. (docs.optimism.io)
What Ethereum.org says you’re choosing between
- Sidechains: independent EVM chains bridged to Ethereum, with their own validators and block parameters; they do not inherit L1 security or post full transaction data/state changes back to Ethereum. (ethereum.org)
- Rollups: off-chain execution with settlement and data availability on Ethereum.
- Optimistic rollups: assume correctness; allow challenges during a roughly week-long window before withdrawals finalize to L1. (ethereum.org)
- ZK rollups: prove correctness up front using validity proofs; withdrawals finalize once proofs are verified on L1. (ethereum.org)
- Validium/Volition: ZK proof systems that keep data off-chain (validium) or let apps choose per-transaction DA mode (volition); higher throughput/lower fees, but DA trust shifts to a committee or external DA layer. (ethereum.org)
Why this matters: the blend of settlement (L1), DA path (L1 blobs vs off‑chain DA), and proof scheme determines both the security envelope and the throughput–cost curve your product experiences.
Cost drivers in 2026: what actually moves your bill
- On rollups, L1 data availability dominates costs. EIP‑4844 introduced blob-carrying transactions with their own market and fee mechanics; most major L2s moved from calldata to blobs, cutting costs materially. Blobs target 3 per block (max 6), each ~128 KiB, retained ~18 days; pricing uses a separate blob base fee with an EIP‑1559‑like update rule. (eips.ethereum.org)
- The upshot for users: today’s ETH transfers on popular rollups typically cost low cents; swaps remain cents to sub‑dollar depending on compression, batch size, and stack. Check live snapshots at L2Fees.info when scoping SLAs. (l2fees.info)
- Sidechains don’t pay L1 DA per tx; their cost structure is native gas economics. Typical medians have been:
- BNB Smart Chain: ~$0.01 median in 2024–2025 annual/forward-looking reports; proposals and updates in late 2025 targeted ~$0.005. (bnbchain.org)
- Polygon PoS: ~$0.01 average (Q1 2025) with many days sub‑cent; examples around ~$0.007. (messari.io)
- Gnosis Chain: explorer-reported averages around ~$0.001 in recent snapshots. (gnosisscan.io)
Practical implication: if your workload is bandwidth‑heavy (big calldata/state diffs) and latency‑tolerant, sidechains or validium modes can drop fees to near‑zero. If you need Ethereum‑grade settlement assurances, blobs have made rollups cheap enough for many B2C flows.
Throughput realities: observed, not theoretical
- Rollups scale with L1 data bandwidth, compression, and proving cadence. Ethereum.org’s own walkthrough shows how aggressive compression can push theoretical limits to thousands of TPS across L2s—but rollups still share finite L1 blobspace. (ethereum.org)
- In practice, the ecosystem often sets new highs via specialized chains. Recent L2BEAT/press snapshots reported combined L2/Layer‑3 peaks in the hundreds of TPS (e.g., June 2024 all‑time highs around ~246 TPS across the scaling stack). Expect spikes around app‑specific chains and gaming L3s. (cointelegraph.com)
- Sidechains scale by choosing faster blocks and bigger gas limits. BNB Chain reported averages near 4M–12M daily tx and fees near a cent; Polygon PoS handled ~3.4–3.8M daily tx in 2025 reports; Gnosis Chain targets 5s blocks and 30M gas blocks. (bnbchain.org)
Key takeaway: if you need very high sustained TPS independent of Ethereum blobspace—or strict, predictable low-latency finality—sidechains (or validium/app‑specific rollups leveraging external DA) remain compelling. If you need Ethereum’s settlement guarantees, rollups are now cheap and fast enough for many at-scale consumer apps.
Security and maturity: what changed in 2024–2025
- OP Stack fault proofs went live on OP Mainnet (June 10, 2024) and were later announced as permissionless, moving OP chains into L2BEAT Stage‑1 territory. (docs.optimism.io)
- Arbitrum activated BoLD (permissionless validation) on Arbitrum One and Nova on Feb 12, 2025, after DAO approval—a substantive decentralization milestone. (theblock.co)
- Use L2BEAT’s Stages and DA Risk frameworks to evaluate whether a network is a rollup (DA on Ethereum), a validium/optimium (external DA), and how upgradeability/committees affect exits. This is crucial for policy, treasury, and custody approvals. (l2beat.com)
Sidechains, by design, rely on their own validators and bridges; you’re accepting separate consensus/bridge risk in exchange for speed and cost. Ethereum.org’s guidance is consistent on this trade-off. (ethereum.org)
Concrete cost-throughput snapshots (Jan 2026)
Rollups (user-facing fees, live snapshots vary with ETH price and blob demand):
- Arbitrum One: send ≈ $0.09; swap ≈ $0.27.
- Optimism: send ≈ $0.09; swap ≈ $0.18.
- zkSync Era: send ≈ $0.07.
- Starknet: send ≈ $0.19; swap ≈ $0.57.
- Polygon zkEVM: send ≈ $0.19; swap ≈ $2.75. (l2fees.info)
Sidechains (representative medians/averages; confirm in your env):
- Polygon PoS: average around ~$0.01 in Q1 2025; daily activity in the 3–4M tx range; Coindesk observed ~$0.007 days. (messari.io)
- BNB Smart Chain: 2024 annual median ~$0.03; 2025 outlook notes ~$0.01 median with peaks to >12M daily tx. (bnbchain.org)
- Gnosis Chain: explorer averages around ~$0.001. (gnosisscan.io)
Observed throughput context:
- Ecosystem peaks across L2/L3 hit ~246 TPS on June 16, 2024; individual chains vary widely by day and app mix. (cointelegraph.com)
Practical examples with precise numbers
Scenario A: 100,000 on‑chain transfers/hour (payments rail)
- Rollup baseline: assume $0.07 per transfer (midpoint of current ranges). Hourly fee ≈ $7,000; daily ≈ $168k. Execution time: seconds on L2; L1 settlement immediate for optimistic “soft” UX but L1‑final withdrawals take ~7 days; ZK rollups finalize within hours post‑proof. (l2fees.info)
- Polygon PoS: assume $0.005–$0.01 average; hourly fee ≈ $500–$1,000; daily ≈ $12k–$24k; near‑instant finality on the sidechain; settlement back to Ethereum governed by the bridge. (messari.io)
- Gnosis Chain: assume ~$0.001; hourly fee ≈ $100; daily ≈ $2,400. (gnosisscan.io)
Scenario B: Exchange‑like throughput target, 2,000 TPS of small transfers for a promo window (15 minutes)
- Rollups: feasible if you secure enough blobspace capacity and compress to small state diffs; monitor blob base fee and batch sizing, consider multiple parallel rollups or L3 for spikes. (eips.ethereum.org)
- Sidechains: scale block gas limits and validator throughput; BNB Chain reports handling >12M daily tx with ~3s blocks and cent‑level fees. (bnbchain.org)
Scenario C: NFT game with millions of micro‑actions
- Consider validium/volition (e.g., StarkEx/Immutable) to push fees toward zero and keep L1 settlement for proofs. Immutable commonly cites 9,000+ TPS capabilities (validium mode) and no per‑tx gas to users, monetized via protocol/market fees. (immutable.com)
Best emerging practices we recommend in 2026
- Start with a security envelope, then pick the DA mode
- If the business cannot tolerate DA committee risk, stick to full rollup (DA on Ethereum). If margins are razor‑thin and UX needs sub‑cent, consider validium/volition or a sidechain—but document DA/bridge assumptions (board and risk will ask). Lean on L2BEAT DA‑risk scoring. (forum.l2beat.com)
- Design for blob‑aware operations on rollups
- Compress aggressively; fill blobs fully (avoid paying for unused space). Watch the blob base fee (EIP‑7516 BLOBBASEFEE) in your contracts and batchers; consider proof aggregation cadence vs. UX finality promises. (eips.ethereum.org)
- Use the decentralization scorecards, not marketing slides
- Require Stage‑1 or better (permissionless exits) for any network holding significant user balances. Check whether proofs are live in production, not just “coming soon.” Track OP Stack and Arbitrum BoLD status changes in your vendor checklist. (optimism.io)
- Bridge policy: canonical first, then specialized if you must
- Prefer canonical L1<->L2 bridges. For optimistic systems, communicate the ~7‑day withdrawal to treasury/custody; if you need fast exits, integrate reputable LPs with pre‑funding and clear SLAs. (ethereum.org)
- Throughput planning: test at blob peaks, not averages
- If your launch window coincides with a congested market, blob fees can spike. Model worst‑case blob pricing from historical ranges and rehearse fallback modes (e.g., defer heavy ops, switch to cheaper DA mode on a volition chain, or burst to an app‑specific L3). (blocknative.com)
- For sidechains: operational due diligence equals security
- Validate validator set size/diversity, block producer rotation, bridge governance, incident history, MEV/ordering protections, and fee‑policy stability (e.g., BNB fee halving proposals). Budget for L1 settlement exposure if you bridge. (bnbchain.org)
Rollups vs sidechains: when to pick what (2026 edition)
Choose a rollup when you need:
- Ethereum‑level settlement guarantees, transparent DA on L1, and predictable compliance/audit posture.
- Reasonable costs at scale post‑Dencun; you can design around blob variability and proof cadences. (ethereum.org)
Choose a sidechain (or validium/volition) when you need:
- Sub‑cent fees at very high throughput and can accept independent validator/bridge trust.
- Ultra‑low latency and elastic capacity for spikes (gaming, high‑frequency payments, micro‑interactions). (ethereum.org)
Hybrid patterns we see working:
- Product on an L2 rollup; high‑volume, low‑security‑sensitivity flows (e.g., in‑game actions) on a validium or sidechain; settle high‑value states to L1/L2 on a schedule. (ethereum.org)
A quick, honest comparison (numbers you can plan with)
- Security anchor:
- Rollups: Ethereum.
- Sidechains: their own validators/bridges. (ethereum.org)
- Finality to L1:
- Optimistic rollups: user withdrawals ~7 days; “soft” UX is near‑instant on L2. (ethereum.org)
- ZK rollups: proofs posted and verified in hours (varies by stack and aggregation). (docs.zksync.io)
- Fees today:
- Rollups: cents per transfer, cents‑to‑sub‑dollar per swap. (l2fees.info)
- Sidechains: sub‑cent to a few cents. (messari.io)
- Throughput:
- Rollups: collectively hundreds of TPS in the wild, higher with app‑specific L3 spikes; bounded by blobspace. (cointelegraph.com)
- Sidechains: scale with block params; multi‑million daily transactions are routine. (bnbchain.org)
Implementation checklist (what we do with clients)
- Define your security envelope: do you require DA on Ethereum? If not, could volition reduce your unit costs for specific flows? (ethereum.org)
- Pick a short list and check L2BEAT Stages/DA risk; require Stage‑1+ and clearly documented DA path. (l2beat.com)
- Model fees under stress: simulate blob spikes (EIP‑4844) and ETH price bands; design batch sizes to fill blobs. (eips.ethereum.org)
- Decide finality UX: if ZK, communicate “soft seconds, hard hours”; if optimistic, communicate the ~7‑day L1 exit while offering fast‑withdraw partners with strict SLAs. (ethereum.org)
- Bridge guardrails: canonical first; if using third‑party bridges, document signers, upgrade keys, timelocks, and incident response. (ethereum.org)
- Throughput drills: load‑test at your peak business cadence; for sidechains, validate validator capacity and gas policy; for rollups, monitor blob base fee and purposely saturate batchers in staging. (eips.ethereum.org)
Bottom line
- If you must inherit Ethereum security and want mainstream‑ready fees, rollups are now “cheap enough” for many consumer and enterprise apps, especially post‑Dencun. Use OP Stack/Arbitrum stacks that have shipped permissionless proofs, and keep an eye on their Stages status. (ethereum.org)
- If your business model lives or dies by sub‑cent fees at extreme throughput and you can accept added trust assumptions, a well‑run sidechain or validium/volition can be optimal—especially for gaming, loyalty, and micropayments—while anchoring critical settlements on Ethereum. (ethereum.org)
7Block Labs helps architecture teams quantify these trade‑offs with cost profiles, throughput drills, and governance due diligence so you can deploy with confidence.
References and further reading:
- Ethereum.org on sidechains, scaling, optimistic and ZK rollups. (ethereum.org)
- EIP‑4844 and blob gas market. (eips.ethereum.org)
- Live fee snapshots (L2Fees) and ecosystem activity (L2BEAT monthly). (l2fees.info)
- Polygon PoS costs and activity. (messari.io)
- BNB Chain fees and throughput. (bnbchain.org)
- Gnosis Chain specs and fees. (docs.gnosischain.com)
- L2 decentralization and DA risk frameworks. (l2beat.com)
- Fault/fraud proof milestones (OP Stack, Arbitrum BoLD). (docs.optimism.io)
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