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Part 6 of 7 · Menu cost calculator series ~5 min read

What the menu cost calculator costs

The only model call is reading an invoice, and costings recompute weekly across the whole menu. A hundred and twenty dishes is a substantial menu or several sites. Here is where each cent goes.

Key takeaways

  • About $49 a month at 120 dishes. Roughly $202 at 500 dishes.
  • One Bedrock read per dish is the only line that scales. Everything else is rounding.
  • Nothing is always-on, so a quiet month genuinely costs almost nothing.
  • Invoice reading is the only variable; recosting every dish weekly is a rounding error.
  • The duplicate test runs before the read, so resends are free.
  • The three real risks: a retry loop, storage nobody expires, and a bigger model than the job needs.

The bill at three volumes

These are US East prices at the time of writing, at three volumes that bracket most small businesses. Find the bar closest to your own and read across.

Monthly cost of the menu cost calculator at three volumesA stacked bar chart with three bars, one per volume tier: 40 dishes totalling about $17, 120 dishes totalling about $49, and 500 dishes totalling about $202. Each bar is stacked from bands. The largest and fastest-growing is Bedrock, one read per dish, in teal. Then SES for the messages, in pink. Then S3 and DynamoDB storage in green. Then a fixed orange band for Secrets Manager and AWS Budgets, which is eighty-six cents at every volume. Then a grey band for Lambda, SQS and CloudWatch. A note says the read is the only bar that grows with the business and the orange band never moves.$0$100$200$300$400~$17.340 dishes~$49.42120 dishes~$202500 dishesBedrock — one read per dishSES — asks, results, receiptsS3 + DynamoDBFixed — Secrets Manager, BudgetsLambda, SQS, CloudWatchThe read is the only bar that grows with the business. The orange fixed band never moves.
Fig 1. The monthly bill at three volumes. The teal band — one model read per dish — is the only part that grows; the orange fixed band is the same 86 cents at every volume.

Line by line

LineAt 120 dishesHow it scales
Bedrock read$48.00Linear. One call per dish, roughly 1,800 in and 200 out tokens.
SES$0.06Linear. About 0 messages per dish.
DynamoDB + S3$0.30Storage grows with what you retain, not with throughput.
Lambda + SQS$0.12Linear, and effectively free at this scale.
CloudWatch$0.16Flat, if you set retention. Unbounded if you do not.
Secrets Manager$0.40Flat. One secret, $0.40 a month.
AWS Budgets$0.46Flat. Two actions, so you find out before the bill does.

The read band is invoice lines rather than dishes; it is expressed per dish here for comparability. Nothing is emailed, so there is no messaging line.

The three ways this bill surprises you

Every one of these has happened to somebody, and all three are cheap to prevent.

  • Reading invoices that arrive as a file. Many suppliers provide structured data. Parsing it removes the only model cost in the system.
  • Recosting on every price change. Weekly is enough, and it produces a clean series that can be compared.
  • Storing costings without pruning. Weekly costings for five hundred dishes is tiny, but keep full detail for two years and roll up beyond that.

What it costs when nothing happens

This matters more than the headline number for a seasonal business. In a month with nothing to process the bill is the fixed band: Secrets Manager at forty cents, AWS Budgets at forty-six, and a few cents of storage. Call it a dollar. There is no instance to stop and nothing to remember to turn off.

The monthly bill at four volumes plus one failure modeA horizontal row of five boxes. Quiet month, about one dollar. 40 dishes, about $17. 120 dishes, about $49. 500 dishes, about $202. And one bad retry loop, about two hundred dollars. A note says four of these are the design working and the fifth is a missing dead-letter queue.THE BILL, AT A GLANCEQuiet month~$140 dishes~$17120 dishes~$49500 dishes~$202One bad loop~$200Four of these are the design working. The fifth is a missing dead-letter queue.
Fig 2. The bill at a glance, including the one that is not a volume at all. A retry loop with no dead-letter queue costs more than every legitimate use of the system put together.
  • Management
  • Analytics
  • Front-end & mobile

Set these on day one

  • A dead-letter queue on every SQS queue, with a maximum receive count of three.
  • Thirty-day retention on every CloudWatch log group. There is no default that is safe.
  • An S3 lifecycle rule on the object prefix, tiering at 90 days and expiring at your actual record-keeping horizon.
  • Two AWS Budgets actions — one that emails at half your expected spend, one at double it. The second is how you find out about a loop in an hour instead of a month.
  • Provisioned concurrency: none. Nothing here is latency-sensitive enough to justify paying for a warm function.

Next: the same system drawn for engineers — service names, resource identifiers, IAM scopes, table schemas and the model id.

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