Date Calculator
Calculate the exact days, weeks, months, and years between two dates.
Open ToolFree Online Date Calculators & Tools
Great Tools gives you fast, accurate, browser-based calculators for date planning and utility workflows. Use our free tools to calculate date differences, add or subtract days, check business-day timelines, validate JSON, and encode Base64 without installing anything.
Use our free online tools to calculate date differences, add or subtract days, months, or years, and count business days instantly. You can also format JSON, convert JSON to C# classes, and encode or decode Base64 data. All tools are fast, accurate, and require no signup.
✓100% Free to use
✓No login required
✓Instant results
✓Accurate calculations
Browse All Tools
Choose a tool and start instantly.
Add Days to Date
Add a number of days to any date for planning deadlines and schedules.
Open ToolSubtract Days from Date
Subtract days from a target date to find start dates or lead times.
Open ToolBusiness Days Calculator
Count weekdays between dates and skip weekends for work planning.
Open ToolAge Calculator
Find exact age in years, months, and days from a birth date.
Open ToolJSON Formatter
Format, validate, and minify JSON quickly in your browser.
Open ToolJSON to C#
Convert JSON payloads into C# classes for models, DTOs, and API contracts.
Open ToolBase64 Tool
Encode and decode Base64 text for payloads, APIs, and debugging.
Open ToolExplore popular online toolsincluding date calculators, JSON formatter, Base64 encoder, and more to simplify your daily tasks quickly and accurately.
Popular Online Calculators and Tools
Why use Great Tools?
Great Tools provides fast, accurate, and easy-to-use online tools for everyday calculations and development needs. Whether you are planning schedules, calculating time differences, or working with JSON and Base64 data, our tools help you save time and avoid manual errors. All tools work directly in your browser with no installation required.
Frequently Asked Questions
Are these calculators free to use?
Yes. Great Tools calculators are free to use online with no registration required.
Do the date tools include leap-year logic?
Yes. Date calculations account for leap years and calendar boundaries automatically.
Can I use Great Tools on mobile?
Yes. Great Tools pages are responsive and work across mobile, tablet, and desktop browsers.
Is my data handled in the browser?
Core calculator operations run in the browser. Review each tool page for feature-specific privacy notes.
Are these tools free to use?
Yes, all tools on Great Tools are completely free to use without any hidden charges.
Do I need to sign up to use the tools?
No, you can use all tools instantly without creating an account or signing in.
Are the calculations accurate?
Yes, all calculations are based on standard date and data processing logic to ensure accurate results.