Why Complexity Matters

Unlike traditional REST endpoints, GraphQL lets clients request exactly the data they need. However, a deeply nested query can inadvertently trigger expensive database joins or third-party calls. Many API gateways therefore assign a cost to each field and limit the total complexity a query may consume.

Formula Overview

Our calculator keeps things simple by assuming each selected field has the same cost. The total complexity is therefore:

where $n$ is the number of fields and $w$ is the weight or cost per field. A more advanced approach assigns different costs to individual fields based on database impact, but this baseline model quickly highlights queries that might be too demanding.

Practical Use

Enter how many fields the client is requesting and the estimated cost per field. For instance, if an image transformation counts as 5 points while simple text retrieval counts as 1, you can approximate the total complexity and enforce a threshold. This helps protect your backend from overly expensive operations, keeping response times predictable for all users.

Best Practices

When designing a GraphQL schema, think carefully about which fields expose heavy logic. You may want to assign higher weights or move those operations behind specialized endpoints. Monitoring production queries also reveals how real clients interact with your API, informing more accurate cost models.