Bitcoin onchain transfer estimates vary sixfold in BIS study

Why transaction output treatment matters

Researchers at the Bank for International Settlements found that estimates of Bitcoin's onchain transfer value can differ by as much as sixfold depending on how transaction outputs are treated. The study, released in September 2026, highlights inconsistencies in measuring blockchain activity across different analytical methods. The findings raise concerns about the reliability of onchain data used for economic research and policy decisions.

The BIS working paper analyzed how various heuristics for identifying economic transactions affect the total value transferred on Bitcoin's blockchain. Researchers compared multiple approaches to filtering out change addresses and non-economic transfers, discovering that the choice of method significantly alters results. For Ethereum and stablecoins, variations were smaller but still notable, suggesting that measurement challenges extend beyond Bitcoin alone. The study emphasizes that without standardized protocols, comparisons between chains or over time may be misleading.

How reliable are current onchain metrics for policy?

The core issue lies in distinguishing between funds moved for economic purposes and those returned to the sender as change. Bitcoin transactions often include multiple outputs, one of which may be change sent back to the payer's wallet. Different analytical models apply varying rules to identify and exclude these outputs, leading to wide discrepancies in final transfer value estimates. Some methods count nearly all outputs as economic activity, while others apply strict filters that remove a large portion of transactions. This variability undermines confidence in onchain metrics used to assess network usage or adoption trends.

The BIS researchers caution that policymakers and analysts relying on raw onchain data may draw incorrect conclusions about cryptocurrency usage. They note that while Ethereum and stablecoin transfers show less variation, the absence of a universal standard still poses risks for cross-chain comparisons. The paper calls for greater transparency in methodology when reporting blockchain statistics and suggests developing industry-agreed guidelines for filtering transaction data. Without such steps, the risk of misinterpreting blockchain activity remains high.

What caused the sixfold variation in Bitcoin transfer estimates? The variation stemmed from differing approaches to identifying and excluding change outputs in Bitcoin transactions, which significantly altered the calculated value of economic transfers.

Frequently Asked Questions

Does this issue affect Ethereum and stablecoin measurements? Yes, though to a lesser extent; Ethereum and stablecoin transfer estimates also showed variability depending on methodology, though the range was narrower than for Bitcoin.

What do researchers recommend to improve data reliability? They recommend standardizing heuristics for transaction filtering, increasing methodological transparency, and developing industry-wide guidelines to ensure consistent and comparable onchain metrics.