Bitcoin, the world’s largest cryptocurrency, has long faced scrutiny over its environmental impact. Central to this debate is the energy-intensive process of mining that underpins its decentralized network. In this article we explore in detail, the Bitcoin carbon footprint.

Data centers convert electricity to computation which is the source of carbon emissions.
In recent years, the rapid development of large-scale computing systems has driven a significant increase in global electricity consumption. From the proliferation of large language models (LLMs) powering artificial intelligence applications to the energy demands of social media platforms, computational power has become a cornerstone of modern infrastructure.
These technologies rely on vast data centers and specialized hardware, consuming substantial amounts of electricity. Bitcoin, as one of the most prominent examples of energy-intensive computation, exemplifies how the rise of decentralized systems has contributed to this trend.
Prior, ShrinkThatFootprint has covered the carbon footprint of training and using language models, as well as social media. This article explores the carbon footprint or carbon cost of Bitcoin, distinguishing between the emissions from mining and those tied to transactions, while providing meaningful comparisons for context.
Bitcoin, Carbon Footprint from Mining and Transactions
How Mining Works
Bitcoin mining relies on a consensus mechanism known as proof-of-work (PoW), where miners solve complex cryptographic puzzles to validate transactions and secure the blockchain. This process ensures decentralization and security but comes at a significant energy cost. Mining is a continuous operation, requiring powerful hardware and vast amounts of electricity.
The total mining activity is estimated to be approximately 350 exahashes per second (EH/s). This means that the combined effort of all active miners globally is generating 350 quintillion (350 × 10¹⁸) hash computations every second. The network does not inherently operate at this hash rate by design; instead, this figure reflects the estimated total contribution of all mining hardware currently active.
Each miner contributes a portion of this total, with their individual machines performing hashes at speeds typically measured in terahashes per second (TH/s). The aggregate hashrate depends entirely on the number of miners participating and the computational power of their hardware. If miners join or leave the network, the total hashrate adjusts accordingly.
Computing Mining Carbon Costs from First Principles
To compute the carbon cost of Bitcoin mining, we start with the three key variables:
- Network Hashrate: Bitcoin’s total computational power is approximately 350 exahashes per second (EH/s).
- Energy Efficiency: Modern mining hardware (e.g., Antminer S19) operates at around 30 joules per terahash (J/TH). Tera is a prefix that represents 10^15, which is 1000 times more than “Giga” or 1000 times less than “Peta”.
- Global Energy Intensity: The average carbon intensity of electricity is approximately 450 grams of CO₂ per kilowatt-hour (gCO₂/kWh).
Step 1: Total Energy Consumption
To calculate the total energy consumed by mining annually, use the following formula:
Energy (kWh) = Hashrate (EH/s) × Energy Efficiency (kWh/TH) × Seconds in a Year
Breaking it down step by step:
- Hashrate: 350 EH/s is equivalent to 350 million terahashes per second (350 × 10⁶ TH/s).
- Energy efficiency: 30 J/TH can be converted to kilowatt-hours as 30 ÷ 3,600,000 = 8.33 × 10⁻⁶ kWh/TH.
- Seconds in a year: There are 31.5 million seconds in a year (365 × 24 × 60 × 60).
Now substitute these values into the formula: Energy (kWh) = 350 × 10⁶ × 8.33 × 10⁻⁶ × 31.5 × 10⁶
This simplifies to: Energy (kWh) ≈ 91.6 terawatt-hours per year (TWh/year).
Thus, Bitcoin mining consumes approximately 91.6 TWh annually.
Step 2: Carbon Emissions
Globally, the average carbon intensity of electricity generation is estimated to be 450 grams of CO₂ per kilowatt-hour (gCO₂/kWh). This figure reflects a mix of energy sources, including fossil fuels like coal and natural gas, which are high-emission, as well as renewable sources like hydro, wind, and solar, which are low or zero-emission.
To compute the carbon emissions, use the formula:
Carbon Emissions (CO₂) = Energy (kWh) × Carbon Intensity (gCO₂/kWh)
Substitute the values:
- Energy consumption: 91.6 × 10⁹ kWh/year.
- Carbon intensity: 450 gCO₂/kWh.
Carbon Emissions (CO₂) = 91.6 × 10⁹ × 450
This simplifies to: Carbon Emissions (CO₂) ≈ 41.2 million metric tons of CO₂ (MtCO₂/year).
The Bitcoin network’s mining operations consume an estimated 91.6 terawatt-hours (TWh) of electricity annually—comparable to the energy usage of countries like Finland (which currently emits about 25% less than this number). The associated carbon emissions are approximately 41.2 million metric tons of CO₂ (MtCO₂) per year. These emissions are heavily influenced by the energy sources miners use, with coal and natural gas dominating in some regions, while renewables play a role in others.
The Carbon Cost of Bitcoin Transactions
What is a Transaction
Mining is not the only computation that contributes to the bitcoin carbon footprint. There are also transactions. A Bitcoin transaction occurs when someone sends Bitcoin to another party. While transactions are verified and included in blocks by miners, the computational effort for individual transactions is relatively small. Instead, the energy consumed for transactions arises from the network of Bitcoin nodes—computers that validate and relay transactions globally.
Transaction-Specific Emissions
Bitcoin has roughly 50,000 active nodes globally, each consuming about 200 watts of electricity. The network processes approximately 350,000 transactions daily, translating to:
- Daily node energy consumption: 240,000 kWh.
- Energy per transaction: 0.686 kWh.
- Carbon emissions per transaction: 309 grams of CO₂.
On an annual scale, transaction-related emissions total 39,431 metric tons of CO₂. This represents just 0.1% of the network’s mining-related emissions, highlighting the negligible direct impact of transactions compared to mining.
Mining vs. Transaction Emissions
Key Metrics
- Annual mining emissions: 41.2 MtCO₂ (~99.9%).
- Annual transaction emissions: 39,431 tCO₂ (~0.1%).
Implications
Mining dominates Bitcoin’s environmental impact. Even if transaction volumes were to double, the overall energy use and emissions from transactions would remain a fraction of those from mining.
Contextualizing Bitcoin’s Carbon Footprint
Comparisons with Countries
Bitcoin mining’s annual emissions of 41.2 MtCO₂ are comparable to the total carbon emissions of Sweden, a developed nation with a population of 10 million. In contrast, the total transaction-related emissions of 39,431 tCO₂ are equivalent to the annual emissions of approximately 4,300 average U.S. citizens.
Comparisons with Other Activities
- The annual emissions from mining are equivalent to those of about 9 million gas-powered cars, each driving 11,500 miles per year.
- A single Bitcoin transaction (309 gCO₂) is comparable to driving a gas-powered car approximately 1.2 kilometers (0.75 miles).
Comparisons with Traditional Financial Systems
Traditional payment systems like Visa and Mastercard are vastly more energy-efficient. Visa’s estimated energy use per transaction is around 0.01 gCO₂, a negligible figure compared to Bitcoin’s 309 gCO₂ per transaction! This stark contrast highlights the inefficiency of Bitcoin’s PoW mechanism for transaction processing.
Conclusion – The Bitcoin Carbon Footprint
Bitcoin’s carbon footprint is overwhelmingly driven by its mining operations, which account for nearly all of the network’s emissions. Transactions contribute a minuscule share, both in energy consumption and carbon cost.
To put this into perspective, Bitcoin mining’s emissions rival those of entire nations, while transaction emissions are equivalent to the activities of a small town. By separating these two sources, we get a clearer understanding of where Bitcoin’s environmental impact truly lies and the scale of its footprint relative to other activities and systems.