---
title: "Calculate the difference between two dates in days, weeks, months, years, and business days. Accepts dates in YYYY-MM-DD format. Returns the absolute difference (order doesn't matter) plus a flag indicating whether the end date is in the future relative to start. Business days count only Monday through Friday. Useful for project planning, deadline tracking, contract duration calculations, and age computations."
method: POST
path: "/api/date_difference"
tags: ["general"]
---

# Calculate the difference between two dates in days, weeks, months, years, and business days. Accepts dates in YYYY-MM-DD format. Returns the absolute difference (order doesn't matter) plus a flag indicating whether the end date is in the future relative to start. Business days count only Monday through Friday. Useful for project planning, deadline tracking, contract duration calculations, and age computations.

`POST /api/date_difference`

## Request

- Base URL: `https://calc.engineer`
- URL: `https://calc.engineer/api/date_difference`
- Auth: none declared

## Request body

- object
  - `start_date` string, required: Start date in YYYY-MM-DD format (e.g., '2024-01-15').
  - `end_date` string, required: End date in YYYY-MM-DD format (e.g., '2024-12-31').

## Response `200`

Computed result for date_difference

- object
  - `result` object, required
    - `days` number, required: Total number of days between the two dates (absolute value).
    - `weeks` number, required: Number of complete weeks.
    - `months` number, required: Approximate number of months (days / 30.44).
    - `years` number, required: Approximate number of years (days / 365.25).
    - `business_days` number, required: Number of weekdays (Monday-Friday) between the dates.
    - `is_future` boolean, required: True if end_date is after start_date.
  - `tool` string, required
  - `version` string, required
  - `computed_at` string, date-time, required
  - `chain` object, required
    - `feeds` unknown[]
      - unknown
    - `accepts_from` unknown[]
      - unknown

## Other responses

- `400`: Validation error or invalid JSON
- `404`: Tool not found

---

[API](https://skmtc.dev/calc/apis/calc-engineer-api.md) · [All operations](https://skmtc.dev/calc/apis/calc-engineer-api/llms.txt) · [OpenAPI document](https://skmtc.dev/calc/apis/calc-engineer-api/revisions/8830480ec488?raw)