Enter an age and a reference date to find the approximate Date of Birth.
Select your Date of Birth. Click "Calculate Human Age". View your age and details like Zodiac, birthstone, generation, milestones, historical facts, fun facts, etc. Hover over for info. Use Share to copy results.
Select the "Pet Age" tab. Enter pet's Date of Birth. Choose Pet Type / Breed. Click "Calculate Pet Age" for age in human years.
Select the "Reverse DOB" tab. Enter the age in Years, Months, and Days. Select the "Age As Of Date" (defaults to today). Click "Find Date of Birth" to calculate the corresponding birth date and see related info like day of week and zodiac signs.
Select the "Due Date" tab. Enter the first day of the Last Menstrual Period (LMP). Optionally, enter your average Cycle Length in days (default is 28 if left blank) for a potentially more accurate estimate. Click "Calculate Due Date" to see the estimated due date, approximate current gestational age, related fun facts, and a simple timeline.
This calculator uses a dark theme by default.
Calculator Disclaimer: This calculator provides estimates for informational and entertainment purposes only. Calculations, especially for pets and due dates, are approximations based on common formulas and may not reflect individual variations. Always consult with qualified professionals (medical, legal, financial, veterinary, etc.) for critical decisions or specific advice. No data entered is stored on this site.
Ever needed to find your exact birthdate but didn’t have it written down? Whether you're completing official forms, verifying age for healthcare, or helping someone without documentation, a date of birth calculator can help. This free online tool lets you figure out a birthdate using just someone’s age or a specific reference date—quickly and accurately.
In this article, we’ll show you how our date of birth calculator works, when you might need it, and how it can save you time and guesswork. It's ideal for personal, professional, and even legal uses. Let's dive in.
A date of birth calculator is a simple, web-based tool that estimates a person’s birthdate based on:
The tool subtracts the given age from the reference date and provides an accurate result. It’s especially useful when birth records are missing or unclear.
The calculator uses a straightforward formula:
Reference Date – Age = Estimated Date of Birth
Example: If someone is 30 years old today (April 12, 2025), the calculator subtracts 30 years from today’s date and gives April 12, 1995.
Our calculator is designed to be:
It also takes into account leap years and calendar variations, ensuring the result is as precise as possible.
There are countless practical situations where a date of birth calculator becomes incredibly helpful:
Using our tool is simple and takes just seconds:
That’s it—no math, no guesswork.
Our date of birth calculator was built for real-world reliability. Here’s what makes it stand out:
It’s built for accuracy, privacy, and ease of use—no sign-up necessary.
Here’s how different people use our DOB calculator:
If the age input is exact, the result is accurate to the day. Minor discrepancies may occur if only partial age data is provided.
Yes, just enter the person’s age and your desired reference date. It’s great for caregivers, HR reps, teachers, and case workers.
You can estimate using rough age ranges. The tool will still provide a reasonably accurate birthdate.
No, we do not collect or save any data you enter. It’s 100% private and secure.
While our tool is highly accurate, it’s important to remember:
Still, for quick and reliable DOB estimates, it’s an incredibly helpful solution.
If you work in a setting that often needs DOB estimation—like a school, clinic, or immigration office—you can bookmark or even integrate the calculator into your internal systems. Its responsive design makes it perfect for both desktop and mobile environments.
“From immigration to education, knowing a date of birth isn’t optional—it’s essential. This tool makes it effortless.”
“All you need is an age and a date. We’ll do the rest—accurately, instantly, and for free.”
A date of birth calculator is more than a simple widget—it’s a smart solution to everyday problems. Whether you're confirming your own birthdate or helping others with legal, medical, or school-related needs, our calculator is designed to be your go-to tool.
You don’t need a math degree or a stack of paperwork. Just enter an age, click a button, and get the answer you need.
Try it now—and simplify your next age-related task in seconds.
Article Disclaimer: The information presented in the article above is for general informational purposes only and may not reflect all features of the specific calculator implementation on this page. It does not constitute professional advice.