Add/subtract to a date | Calculate Date Changes Effortlessly
Calculate new dates by adding or subtracting days, months, or years. Input a starting date and adjustment amount for immediate results.
Result
How to Use the Date Calculator
1. Select your starting date and time
2. Choose whether to add or subtract time periods
3. Enter values for years, months, weeks, days, hours, minutes, or seconds
4. Click Calculate to see the result
Key Features
- Calculate future and past dates with precision
- Support for multiple time units
- Instant calculations with real-time validation
- Copy results with one click
Common Use Cases
- Project deadline planning
- Contract term calculations
- Event planning and scheduling
- Age calculations
Use this tool from your AI agent
Free JSON API and Model Context Protocol (MCP) server. No signup, no API key, CORS open. Designed for Claude, ChatGPT, Cursor, scripts and frontend apps.
curl -X POST https://mate.tools/api/v1/date-math.php \
-H "Content-Type: application/json" \
-d '{"start":"2026-05-10","add":"+90 days"}'import urllib.request, json
req = urllib.request.Request(
"https://mate.tools/api/v1/date-math.php",
data=json.dumps({"start":"2026-05-10","add":"+90 days"}).encode(),
headers={"Content-Type": "application/json"},
)
with urllib.request.urlopen(req) as r:
print(json.load(r))const r = await fetch("https://mate.tools/api/v1/date-math.php", {
method: "POST",
headers: { "Content-Type": "application/json" },
body: JSON.stringify({"start":"2026-05-10","add":"+90 days"}),
});
console.log(await r.json()); Add to claude_desktop_config.json (Claude Desktop), ~/.cursor/mcp.json (Cursor), or any other MCP-compatible client:
{
"mcpServers": {
"mate-tools": {
"command": "npx",
"args": ["-y", "@mate-tools/mcp-server"]
}
}
}Frequently Asked Questions
The calculator automatically adjusts for daylight saving time based on your system's timezone settings.
Yes, you can add or subtract any number of years, and the calculator will properly handle leap years.
The calculator automatically adjusts to the nearest valid date. For example, adding one month to January 31st will result in February 28th (or 29th in leap years).
