Free tools for the questions everyone asks: How old am I? How many days until my vacation? What date is 90 days from now? No sign-up, no download — the math runs entirely in your browser.
Start a countdownHere's one of our tools in action, right now:
Counting down to
Your exact age in years, months, and days — plus days lived and your next birthday countdown.
How many days, weeks, and months separate any two dates.
What date is 30, 90, or 180 days from today? Do the math instantly.
Build a live countdown to anything — a wedding, a trip, the weekend — and share it with a link.
Live holiday countdowns — Christmas, Thanksgiving, Halloween, Easter and more, always counting to the next one.
Your 1,000th, 10,000th, and 30,000th day of life each happen exactly once. Find yours — and share it.
A live countdown to the next U.S. general election, with the exact date and how it's set.
Count down to the next spring forward or fall back — which way the clocks move, and when.
A live countdown to the April 15 federal filing deadline, plus extension and refund basics.
NFL teams eat thousands of Uncrustables a week. A live counter estimating this season's total, team by team.
The stories and how-tos behind the numbers — written by me, Dennis, the same person who built the calculators.
Golden birthdays, leap years, Tax Day, election rules, and the rest — plain-spoken articles about the dates behind the tools.
The year your age matches your birth date happens once. Find out if yours is still coming.
Deadlines, extensions, and what really happens if you miss it.
The quarter-day problem the calendar has been patching since Julius Caesar.
Date questions come up constantly: parents working out a child's exact age for school enrollment, travelers counting down to a flight, HR teams calculating notice periods, couples tracking anniversaries. Search engines answer the simplest versions, but the moment you need anything specific — "how old am I in days?", "what date is 120 days after March 3rd?" — a dedicated calculator is faster and less error-prone than doing it by hand or in a spreadsheet.
Everything runs in your own browser using JavaScript. No information you type ever leaves your device — there's nothing to sign up for and nothing stored on a server. That also means the tools work offline once the page has loaded, and results are instant.
Date math is done with real calendar rules, including leap years. For age calculations, "years" means full calendar years since your birthdate, not 365-day chunks. For legal or contractual questions (eligibility dates, notice periods), always double-check against the official rules of the organization involved — day-count conventions can differ by jurisdiction.
Start from the question you're asking. "How old am I, exactly?" is the Age Calculator — it breaks your age down to the day and totals up your days and weeks lived. "How many days are there between two dates?" is the Date Difference calculator, handy for counting down to a trip or measuring how long something has taken. "What date will it be in 90 days?" belongs to Add / Subtract Days. And if a date is special enough to watch it approach, the Countdown Timer turns it into a live clock you can share with a link, so everyone counts down to the same moment together.
Every tool here is free, with no accounts and no downloads, and every answer is worked out on the spot in your browser — the accuracy notes above describe the calendar rules doing the work, including leap years, shorter months, and birthdays that fall on the 29th, 30th, or 31st.
"How many days from November 1 to Christmas?" Open Days Between Dates, put November 1 as the start and December 25 as the end: the answer is 54 days — November contributes 29 days after the 1st, and December adds 25 — and it comes out the same every year, because no February sits inside the span to argue about it. "What date is 45 days after October 15?" That's Add / Subtract Days: enter October 15, 45, days, add — and you land on November 29. Try chaining it: 45 days after that is in mid-January, and the tool handles the year boundary without blinking. "When is my sister's 10,000th day?" Day Milestones takes any birthdate and returns the whole ladder of once-in-a-lifetime dates, with a share link you can send her — half the fun is that she's almost certainly never heard of the day, let alone planned for it.
Most wrong answers in date math come from four traps, and every tool here is built to sidestep them. The off-by-one trap: "days between" and "days including both ends" differ by exactly one — hotel nights use the first, some booking and deadline counts use the second, and the Date Difference page has a checkbox for it. The 30-day-month trap: months run 28 to 31 days, so "six months later" is 181 to 184 days away depending on which months you're crossing. The invisible leap day: any span crossing a February 29 is a day longer than the same span a year earlier. The midnight trap: a countdown with no time set ends at midnight at the start of the big day — great for "days until Christmas," less great for a party that starts at seven.
Every page here is built to work in a phone browser with nothing to install, so the calculator you need at the school office or the rental counter is the same one you used at home. The two shareable tools — the countdown timer and day milestones — carry everything inside their links, so sending one is as simple as pasting it into a text message; there's no account for your family to sign up for before they can see it. Bookmark the tools you reach for twice and they behave like little apps that never need updating. And because everything runs on your own device, the dates you enter — birthdates included — are never sent anywhere, which is more than can be said for most calculator apps.