Babushka for developers

Babushka Market calculators as an API

The API runs the same calculation code as this website: 46 calculators with 92 calculation modes. Send JSON inputs, receive labelled results with units and the method notes. It is free and no API key is required.

Endpoints

REST + MCP

API base: https://babushka-calculators.babushka-market.workers.dev
Catalogue: GET /v1/calculators — calculators, modes and JSON input schemas
Calculate: POST /v1/calculate/:id — inputs plus an optional "mode"
MCP: POST /mcp — one read-only tool per calculation mode

Rules

How requests are checked

Missing inputs use the calculator’s pre-filled example values; send every value you care about.
Unknown inputs, unknown modes and out-of-range values return HTTP 400 with a message.
Calculators that were merged into another tool return HTTP 410 with the replacement ID and mode.
Results are planning estimates with the same limits as the calculator pages.

Working example

Paint for one side of a 10 × 1.5 m fence

15 m² × 2 coats ÷ 10 m²/L = 3 L; with a 10% allowance 3.3 L, which is two 2.5 L tins.

curl -X POST https://babushka-calculators.babushka-market.workers.dev/v1/calculate/bm.home.paint-calculator \
  -H "Content-Type: application/json" \
  -d '{"mode":"paint-fence","length":10,"height":1.5,"sides":1,"coats":2,"coverage":10,"extra":10,"pack":2.5}'

Response (abridged)

{
  "calculatorId": "bm.home.paint-calculator",
  "mode": "paint-fence",
  "result": [
    { "label": "Paintable area", "value": 15, "unit": "m²" },
    { "label": "Paint before allowance", "value": 3, "unit": "L" },
    { "label": "Required quantity", "value": 3.3, "unit": "L" },
    { "label": "Packs to buy", "value": 2 },
    { "label": "Purchase quantity", "value": 5, "unit": "L" },
    { "label": "Left over", "value": 1.7, "unit": "L" }
  ],
  "method": ["Fence calculation uses full face area; slats and gaps alter real use. …"],
  "url": "https://babushka-market.com/home/paint-calculator?mode=paint-fence"
}

MCP configuration

Connect an MCP client

Use the streamable HTTP endpoint below. Tools are named after the calculator ID and mode, for example bm_home_paint-calculator_paint-fence.

URL: https://babushka-calculators.babushka-market.workers.dev/mcp

Supported methods: initialize, ping, tools/list and tools/call. Responses contain MCP text content and structured calculator output.

Optional

Register a free key

A key is not required today, and calls are not linked to keys while that remains true. If you register one, the service stores a one-way hash of your email address, a one-way hash of the key and the key’s first characters so it can be recognised later. The key itself is shown to you once.

What is Babushka Market for?

Babushka Market helps plan quantities and purchases for cooking, home projects, gardens, crafts, parties and shopping. Its calculators show the inputs and assumptions behind a result. They do not inspect your materials or circumstances, so compare the output with product instructions and the measurements you actually have.

Worked planning example

Yes. The moving-box example divides each contents volume by its box capacity and rounds after a 10% allowance: 11 small, 15 medium and eight large boxes. Check the displayed formula and pack rounding, then replace the example measurements and rates with your own inputs.

How can I find the supported calculator IDs?

The existing public calculator catalogue lists 46 calculators and 92 modes checked for this migration. Retrieve /v1/calculators from the documented Babushka calculation-service hostname, then use the returned calculator ID and mode. The catalogue provides fields and defaults; do not invent an ID from the website page title or slug.

What does the moving-box API example return?

The verified moving-volume example returns eleven small, fifteen medium and eight large boxes: 34 in total, plus three tape rolls. It uses 0.3, 0.8 and 0.6 m³ of contents, capacities of 30, 60 and 90 L, a 10% allowance, 3 m of tape per box and 50 m rolls.

Does the website migration change the calculation API?

No. The website continues to call the existing public calculator service and preserves its calculator IDs, modes and input contracts. Only the website source is rebuilt for Cloudflare hosting. Read the existing service documentation for API and MCP usage; no additional authentication credential or replacement calculation Worker is introduced here.

Calculation/content reviewed 4 October 2026. Source: Babushka Market’s displayed formulas, units and labelled editable assumptions. How the estimates work