Digital Storage Carbon Footprint Calculator (Cloud vs Local)
What this calculator estimates
Storing data isn’t “weightless.” Whether your files sit in a cloud data center or on a local hard drive/NAS, hardware must stay powered (and often cooled) and that electricity use creates greenhouse gas emissions when the grid is not 100% renewable. This calculator estimates the annual operational emissions associated with keeping a given amount of data stored for a year, expressed as kg CO2e per year.
It is designed for quick comparisons—especially cloud vs local—using a simple model built from an energy-intensity factor (kWh per GB-year) and your electricity emission factor (kg CO2e per kWh). The result is best used as an order-of-magnitude estimate and a starting point for reducing the footprint of your digital storage.
Inputs: what to enter
1) Stored data (GB)
Enter the amount of data you want to account for, in gigabytes (GB). For context:
- 1,000 GB = 1 TB (terabyte).
- A phone backup or photo library may be 50–300 GB; a small business file share could be multiple TB.
2) Storage type (Cloud vs Local)
Select where the data primarily lives:
- Cloud storage: data stored in a provider’s data centers. This can include additional overhead such as cooling, networking, and multi-tenant infrastructure.
- Local storage: data stored on your own device(s), external drive, NAS, or on-prem server. Energy use depends heavily on whether equipment runs 24/7 and how efficiently it’s utilized.
3) Grid emission factor (kg CO2e per kWh)
This is the carbon intensity of the electricity used to power the storage. A default of 0.50 kg CO2e/kWh is a rough global-ish placeholder. In practice, this varies widely by country/region and by time of day. If you know your local value (or a supplier-specific value), use it for a better estimate.
How the calculation works (formula)
The model is:
Where:
- E = annual emissions (kg CO2e/year)
- D = stored data (GB)
- I = energy intensity (kWh per GB-year)
- f = grid emission factor (kg CO2e per kWh)
This calculator uses typical intensity factors:
- Cloud: 1.5 kWh per GB-year
- Local: 0.5 kWh per GB-year
These values are intentionally simple for usability. Real-world intensity can be lower or higher depending on data center efficiency (PUE), storage media, replication, utilization, and how local devices are powered and used.
Worked example
Scenario: You store 2 TB of data (2,000 GB). You want to compare cloud vs local. Your grid factor is 0.40 kg CO2e/kWh.
- Cloud: E = 2,000 × 1.5 × 0.40 = 1,200 kg CO2e/year
- Local: E = 2,000 × 0.5 × 0.40 = 400 kg CO2e/year
Interpretation: Under these assumptions, cloud storage has ~3× the annual operational footprint of local storage for the same stored GB. That doesn’t automatically mean “local is always greener”—for example, if your local NAS runs inefficiently 24/7, or your cloud provider uses very low-carbon electricity, the comparison can change.
Comparison table (quick intuition)
| Stored data | Cloud (1.5 kWh/GB-yr) | Local (0.5 kWh/GB-yr) | What drives the difference? |
|---|---|---|---|
| 100 GB | Emissions = 100 × 1.5 × f | Emissions = 100 × 0.5 × f | Data center overhead (cooling/network) vs device-level storage |
| 1 TB (1,000 GB) | Emissions = 1,000 × 1.5 × f | Emissions = 1,000 × 0.5 × f | Replication and utilization assumptions matter more at larger sizes |
| 10 TB (10,000 GB) | Emissions = 10,000 × 1.5 × f | Emissions = 10,000 × 0.5 × f | At scale, electricity mix (f) dominates; efficiency improvements have big impact |
How to interpret your result
- It’s annual: the estimate assumes the data is stored for ~12 months. If you store it for 3 months, divide by 4.
- Linear model: doubling GB doubles the estimate. This is a simplification—real systems have fixed overheads and utilization effects.
- Most sensitive input: the grid emission factor can vary dramatically, so customizing it often changes the result more than small changes in the GB estimate.
Ways to reduce the footprint of stored data
- Delete ROT data (redundant, obsolete, trivial) and duplicate backups you no longer need.
- Compress/encode efficiently (e.g., modern video codecs) to reduce stored GB.
- Use lifecycle policies (hot → cool → archive tiers) for cloud storage where feasible.
- Choose lower-carbon electricity (green tariffs, on-site solar, or regions/providers with cleaner grids).
- Right-size local hardware: avoid always-on devices when unnecessary; enable drive sleep; consolidate storage onto fewer, more efficient devices.
Assumptions & limitations (read this)
- Typical intensity factors: Uses fixed kWh/GB-year values (cloud 1.5; local 0.5). Actual values depend on storage medium (HDD/SSD/tape), redundancy, utilization, and facility efficiency.
- Operational electricity only: This model estimates emissions from electricity used to keep data stored. It does not include embodied emissions from manufacturing hardware (servers, drives, devices) or constructing data centers.
- Replication and durability: Many cloud services replicate data across multiple devices/locations; some local setups also do (RAID, backups). The model does not separately parameterize replication—it's “baked into” the typical intensity assumption.
- Data transfer excluded: Uploading/downloading data and ongoing network traffic can add emissions. This calculator is focused on storage-at-rest.
- Grid factor is user-supplied: Using a national average may differ from your provider’s actual mix, time-of-use variation, or a cloud provider’s contracted renewable sourcing.
- Not a compliance tool: For formal reporting (GHG Protocol scopes, supplier questionnaires), use audited provider data and region/provider-specific figures.
FAQ
Is cloud storage always worse than local?
Not necessarily. Cloud can be more efficient per stored GB in some cases (high utilization, efficient facilities, low-carbon electricity). Local can be worse if devices are underutilized and always on. Use this tool for a baseline and refine assumptions for your situation.
What grid emission factor should I use?
Use the most specific value you can (your region or supplier). If unsure, keep the default as a rough placeholder and treat the result as a directional estimate.
Why are the results sometimes large?
At high data volumes (TBs), even small per-GB energy intensities add up over a year. Also, a high grid factor (carbon-intensive electricity) can significantly increase kg CO2e.
Does this include backups and redundancy?
Only indirectly via the typical intensity assumptions. If you keep multiple copies (e.g., 3 backups), consider multiplying your stored GB by the effective number of copies to approximate the added footprint.
Can I use TB instead of GB?
Yes—convert TB to GB by multiplying by 1,000 (e.g., 2.5 TB = 2,500 GB) and enter that value.