> ## Documentation Index
> Fetch the complete documentation index at: https://docs.variable.global/llms.txt
> Use this file to discover all available pages before exploring further.
# Adding inputs to your Product (LCA)
Inputs are how the footprint of a product actually adds up — each row is a quantity of something, and its calculated impact rolls up into the Product (LCA)'s total. This guide explains life-cycle stages and walks you through adding the different types of inputs.
**Input vs. Element vs. Dataset**
* **Input** - *single instance.* A row in a Product (LCA), with a quantity and unit. Each Input belongs to one Product (LCA).
* **Element** - *reusable.* The thing the Input points to (a Material, Energy source, Process, or Transport lane). Elements live in your Inventory and can be referenced by Inputs across many Product (LCA)s.
* **Dataset** - *reusable.* The emission-factor source attached to an Element, supplying impact values per unit.
In this guide you'll add Inputs and point them at Elements. Assigning a Dataset to each Element - covered in [the next guide](/docs/getting-started/assign-datasets) - is what produces calculated impacts.
## Understanding life-cycle stages
Life-cycle assessment divides the environmental impact of a product into stages. Variable supports the standard life-cycle stages:
| Stage | Name | Description |
| :-------- | :-------------------- | :---------------------------------------------------------------------------------- |
| **A1** | Materials | The material inputs that go into your product, plus their cradle-to-gate impacts |
| **A2** | Transport | Transport of those inputs to your manufacturing facility |
| **A3** | Manufacturing | Energy and processes at your facility, as well as waste generated during production |
| **A4** | Transport to customer | Distribution logistics |
| **A5** | Installation | Assembly and installation at customer site |
| **B1-B7** | Use phase | Product operation, maintenance, repair |
| **C1-C4** | End of life | Demolition, waste processing, disposal |
| **D** | Benefits | Credits from recycling and energy recovery |
Stages A1-A3 are often called "cradle to gate" and are the most common scope for a Product Carbon Footprint (PCF). PCFs can also extend beyond A1-A3 to cover downstream stages (A4-A5, B, C, D) when a broader system boundary is needed.
## Adding an input
In the life-cycle stage where you want to add an input (for example, **Cradle to gate (A1-A3)**), click the **+** button to open the input menu.
Select an option from the menu:
Re-use an existing element from your company Inventory
Model a new material and add it to your Inventory
Set energy usage in a production process
Add a transportation leg for distribution and storage
In B-stages, you will also see an **Add Use stage** option for modeling the operation, maintenance, or repair of a product.
Once the input is added, you can edit it directly in the row:
* **Quantity** - amount per functional unit of the product
* **Unit** - unit of measure (kg, m, kWh, etc.)
* **Stage** - move the input to a different life-cycle stage
* **Material group** - taxonomy classification used for dataset matching
For example, if the product is a chair and you use 2 kg of steel, enter "2" with the unit "kg".
## Understanding the input row
After adding an input, you will see it displayed as a row in your Product (LCA). Each row shows:
| Column | Description |
| :------------------------------- | :--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Element** | The named source the Input points to - a Material, Energy, Process, or Transport Element from your Inventory |
| **Notes** | Optional free-text notes for the input |
| **Quantity** | Amount per functional unit, with its unit (item, kg, m, kWh, etc.) |
| **Weight** | Calculated mass of the input |
| **Stage** | The life-cycle stage the input belongs to (A1, A2, etc.) |
| **Material group** | Classifies the input as Product, Packaging, or Other (ancillary). Additional options may appear if the LCA uses a PCR with pre-defined groups. |
| **Data quality** | Aggregate Data Quality Rating (DQR) for the input, computed per the [PACT Methodology v2.0](https://www.carbon-transparency.org/) across the technological, temporal, geographical, completeness, and reliability dimensions |
| **Selected indicator** | Any additional impact indicator you choose (e.g., AP, PENRT, ODP) - switch the indicator using the column header dropdown, and toggle the value between its native unit and % of total using the unit dropdown |
| **GWP-fossil kgCO2e** | Calculated fossil carbon impact in kgCO2e |
| **GWP-fossil % of total** | The input's share of the total fossil GWP of the Product (LCA) |
| **Actions** | Edit, duplicate, or delete the input (via the `⋯` menu) |
**GWP-fossil is Variable's main indicator and is always shown.** The two GWP-fossil columns are always visible on every input row; the **Selected indicator** column is an additional slot you can swap to any other indicator (AP, PENRT, ODP, water use, etc.) for side-by-side comparison.
If the GWP-fossil column shows `--.--`, it means no value is available - typically because the Element the Input points to doesn't have a Dataset assigned yet. A value of `0` is a real result (zero impact), not missing data.
## Adding different input types
### Materials (A1)
A1 Inputs point to **Material** Elements - the materials and components you bring in to manufacture the product. Depending on your perspective that might be what you'd call a raw material - ore, timber, sand - or it might already be processed or pre-formed by the time it reaches you, like steel sheet, plastic pellets, a steel pipe, or a molded housing. They are all valid A1 Elements.
The Dataset connected to a Material Element covers its upstream production from cradle to your gate.
### Transport (A2)
A2 Inputs point to **Transport** Elements - modeled lanes from origin to destination. A lane already encodes everything about the journey: it can have one or many legs, and each leg has its own mode (truck, rail, ship, air), origin/destination, and distance. To add transport to a Product (LCA), pick (or create) a lane and set the weight of material being transported on that Input. Variable calculates the impact from the lane's legs and the weight you provide - you don't re-enter modes or distances on each Input.
### Manufacturing (A3)
A3 Inputs point to **Process** Elements covering what happens at your facility, including things like:
* Electricity usage - whether from the grid (with the appropriate regional or supplier-specific Dataset) or from on-site sources like rooftop solar, on-site wind, or co-generation. Model each source as its own Element so you can mix grid and self-generated electricity in the same Product (LCA).
* Natural gas or other fuels
* Manufacturing processes (welding, machining, coating)
* Water and wastewater treatment
* Waste generated during production - off-cuts, scrap, defects, and any other production waste, with a Dataset for the corresponding waste-treatment or disposal process
Each Input has a quantity in the appropriate unit (kWh, MJ, m3, kg, h, etc.) and points to a Process Element whose Dataset supplies the per-unit impact data for that process.
## Tips for building your Product (LCA)
If you already have a bill of materials in your ERP or PLM system, use it as a starting point. Variable can import BOMs from spreadsheets so you don't have to re-enter inputs by hand.
Prioritize the materials that make up the majority of your product by weight or cost. These typically drive the largest share of environmental impact.
Include packaging materials if they're part of the scope of the product. Add them as separate line items, and set their **Material group** column to **Packaging** so they roll up correctly in reports and EPDs.
## What's next
Each Element your inputs point to needs a dataset assigned before Variable can calculate environmental impact. Learn how to find and assign the right dataset for each Element.
Assign a dataset to each Element to supply its environmental impact data