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Fathom Layer

Fathom Layer / Decision instruments

AI calculators.
Run the numbers.

Estimate model memory, cloud versus local costs, prompt spending and vector storage. Change the inputs and see where your decision changes.

Open the workbench Choose a question

Estimates, not quotes. Every input stays editable.

01 / Find your question

Choose the constraint.

Each instrument solves a different part of a technology decision. Start with the uncertainty in front of you.

01 / INSTRUMENTWill it fit?Model memoryEstimate weights, context cache and runtime overhead for local inference.Open instrument 02 / INSTRUMENTWhen does it pay back?Cloud or localChange workload and operating assumptions to explore a break-even point.Open instrument 03 / INSTRUMENTWhat happens at scale?Prompt volumeTurn a prompt and request volume into a comparable cost estimate.Open instrument 04 / INSTRUMENTHow much memory?Vector storageSize raw embeddings, index overhead and a working memory buffer.Open instrument

02 / Workbench

Change an input.
Watch the answer move.

Use a starting scenario or build your own. Results update as you adjust the controls; the underlying assumptions remain visible.

Instrument 02 / 04

When does it pay back?

Modeled estimate
Explore the sensitivity

Keep a reference. Change one input.

Hold the current estimate, then adjust the controls. Compare how the modeled result changes; the reference stays separate for each instrument.

Current / Live75.00USD/month

Modeled API cost

Includes this scenario's assumed cache discount

USD per 1M tokens: $2 input / $10 output · Standard. Checked 2026-09-16. Official pricing

Cloud Workload

50M
2M
50%

Local Infrastructure

FinOps Summary

API Cost (Monthly)$75.00
Local Energy (Monthly)$124.20
Break-Even PointNo cost break-even
12-mo Savings$-6590
36-mo Savings$-7771
Trade-offsLocal hosting can offer more control over data, but adds maintenance and capacity planning. Cloud APIs can scale with demand, while rates and provider terms may change. This scenario assumes a 90% discount on cached input tokens; verify the selected provider's actual cache terms.

Results depend on the entered assumptions. Recorded prices and modeled memory are not live quotes or measured deployment results.

Continue the decision

Keep your inputs in view as you inspect the next part of the decision.

Energy cost is carried as local running cost. The workbench cache discount is not carried over; include other local expenses.

Open the break-even calculatorExplore compute hardware

03 / Starting points

Begin with a real question.

These are editable example inputs. They are not measurements of a deployed system or current vendor quotes.

ALocal inferenceA 70B model at Q4Start with model weights and a 32K context window. Then change concurrency and see the memory move.Size the model BOperating costA heavier API workloadBegin with 50 million monthly input tokens and a hardware budget. Edit the assumptions before interpreting payback.Explore break-even CVector infrastructureTen million embeddingsExplore memory for 1536-dimensional vectors with an HNSW index. The result is an estimate, not a deployment quote.Size the index

04 / Read the result

A number is only as useful
as its assumptions.

These calculators model a scenario. Memory estimates include model weights, context cache and overhead; cost estimates depend on the workload and rate values shown in the tool. Actual hardware behavior, provider terms and deployment costs may differ.

How Fathom handles evidence Explore hardware on record