Some operations in Firefly Graph have costs that can't be calculated in advance. When that's the case, you'll see a Credits vary indicator next to the Run button instead of a fixed credit estimate. This section explains what that means, why it happens, and what's expected of you when you run a workflow with undetermined costs.
What does "Credits vary" mean?
A standard node has a predictable cost. If you run an image generation node that produces one 1024×1024 image, Firefly Graph knows what that costs and shows you the cost before you run it.
An undetermined-cost node is different: Graph can confirm that credits will be consumed, but the exact total can't be known until the workflow finishes executing. The actual cost is calculated from real usage and reconciled against your account once the run completes.
Why can't some costs be predicted?
There are two distinct reasons a workflow may have undetermined costs.
- The node itself produces variable output: Some nodes are non-deterministic by design. The clearest example is a large language model node — the cost depends on how many tokens the model generates in response to your prompt, and that isn't known until generation is complete. A short answer and a long answer cost different amounts, and Graph has no way to predict which one the model will produce. Other nodes in this category include those that return a variable number of items (for example, an entity-segmentation node that returns however many entities it finds in an input image) or nodes whose output structure depends on the content of the input.
- The graph runs the node a variable number of times: Even a node with a fixed per-execution cost can become undetermined when it's used inside a list, loop, or stream context. If a node runs once per item in an upstream list, and the size of that list is itself produced by an earlier non-deterministic node, the total number of executions — and therefore the total cost — can't be calculated until the workflow runs. This is common in workflows that fan out: a segmentation node returns N entities, and a downstream generation node runs once per entity. Both the count and the per-item cost contribute to a total that's only knowable after the fact.
How undetermined costs are surfaced
Whenever a workflow contains at least one undetermined-cost node or has execution paths that produce variable invocation counts, Graph replaces the usual credit estimate with the Credits vary label. You'll see this in the Run controls before you start a workflow.
Hovering or expanding the indicator shows which nodes in your graph contribute to the variability, so you can inspect the workflow before running it.
What are you acknowledging when you run a workflow?
Running a workflow with Credits varies is your acknowledgment that:
You can review your generative credits at any time by looking at your balance, and you should always monitor graph execution as it begins to process in order to identify cases where it is running more iterations than you would expect.
Managing undetermined costs
A few practical ways to stay in control:
