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CALCULATORS / MOLDING, CASTING AND TOOLING

Tooling versus unit-cost break-even calculator

Fixed tooling cost versus per-part savings; currency is dimensionless account units.

molding-tooling-break-even.napkin / editable
✓ checks pass

SCENARIO COMPARISON

Compare the numbers.

This source describes an analytical model. Its quantities and checks are the view.

Scenariosavingsquantity
15667
15534

All calculated quantities are listed with the inputs. Switch to Source to inspect the equations.

SCENARIOS / CALCULATED VALUESSAME SOURCE

Change an input to see the consequences.

positive unit savings15.00 ✓ passes

BASELINE INPUTS

CALCULATED

savings15
quantity667

Edits change the baseline source.

Calculated from your source · not saved
Baseline · Baseline
positive unit savings15.00 ✓ passes
alternative · alternative
positive unit savings15.00 ✓ passes

Illustrative first-order example. Checks are editable requirements, not design standards. The broader topic may require additional equations, data, and validation.

Formula and units

This example uses the following equations. Input names and units match the editable source above.

savings
savings = alternativeUnit-moldedUnit
quantity
quantity = ceil(tooling/savings)

Original worked example

These are the baseline values in the downloadable source. Edits above let you test your own values.

Given

tooling
10000
alternative unit
20
molded unit
5

Calculated

savings
15
quantity
667

Assumptions and limits

Fixed tooling cost versus per-part savings; currency is dimensionless account units.

The requirement checks use the limits written in this example. Passing a check does not establish that the model covers every load, material behavior, or operating condition in a real design.

Download this .napkin example ↓

Take it further with your agent

Napkin keeps the inputs, equations, checks and assumptions together in one study. Your agent sets it up; you change the numbers.

Try with Claude ↗

codex 'Use Napkin (https://napkin.engineering/mcp, or the local Napkin plugin) to build a study: Tooling versus unit-cost break-even. Inputs: tooling costs; unit costs; scrap; demand. Outputs: break-even quantity; total-cost curves. Model scope: Early process estimates with material and supplier data. Read napkin_capabilities and the current snapshot. Ask me for the values that matter, label assumptions with units, author .napkin source, validate it and apply it with napkin_source using the current revision, then open the study. Add checks for the limits I supply. Keep unsupported analyses explicit.'

Claude needs the Napkin connector; Codex needs the Napkin plugin. Set up your agent ↗

The broader study

The topic brief below describes the broader scope. The worked example above states the particular calculation it implements.

  • Inputs: tooling costs, unit costs, scrap, demand
  • Outputs: break-even quantity, total-cost curves
  • Modes: calculate, compare, sweep
  • Drawing: Part, cavity and runner diagram

EXECUTABLE WORKED EXAMPLE · FIRST-ORDER MODEL · CHECK THE SCOPE & ASSUMPTIONS

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