Count the span between two dates - all days, business days only, or weekends only - with the breakdown and a visual timeline of the range. Useful for deadlines quoted in working days, notice periods and billing windows. Runs fully client-side. Imported Claude artifact. Source: https://github.com/simonw/tools (date-calculator.html, Apache-2.0).

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Details

PricingCompletely free

Security scanClean — skill and frontend scanned

Source simonw/tools

Created2026-08-25

Updated2026-08-25

View source prompt + release files — fork-enabled apps share their full source

System prompt (SKILL.md)

---
name: date-calculator
description: Count the days between two dates - all days, business days only, or weekends only - with a visual timeline.
metadata:
  tags:
    - artifact-import
    - productivity
  source_url: https://tools.simonwillison.net/date-calculator
  github_repo_url: https://github.com/simonw/tools
---

# Date Calculator

An imported Claude artifact. Pick a start and end date, choose whether to count
all days, business days only, or weekends only, and get the span broken down
alongside a visual timeline of the range.

Useful for deadlines and SLAs quoted in working days, notice periods, billing
windows, and any question of the form "how long is that, really?"

The whole calculation runs in the page. Nothing is uploaded, no model is
called, and nothing is metered.

Release files (files)

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