Find My Age
How old were we on that date?
A Chrome extension that shows how old you and your family were on a date you select on any web page — right where you are reading, along with the Japanese era year, the weekday, and how long ago it was.
USE CASES
How old was everyone that day?
Select a date on the page. The ages of the people you registered line up for that day.
Reading an article or a timeline
A year printed on the page does not tell you how old you were at the time. Selecting the date shows it right there, so you do not have to stop reading to do the arithmetic.
Working out how old your children were that day
Counting each child’s age from the date of an entrance ceremony is fiddly enough that you usually skip it. Register up to five people, yourself included, and their ages on that day line up at once.
Checking an "as of this date, aged …" requirement
Eligibility rules are often written as an age on a fixed date, which is exactly the calculation nobody wants to do twice. Select that date and you can see whether you or your family fall inside the condition.
Reading a date on an old document or photo
A date written only in the Western calendar leaves the Japanese era year and the weekday to look up separately. When the date is precise enough, both are shown alongside the ages, together with how far it is from today.
Features
It answers only when you ask.
Reading an old news article, a company history, or a date on a photo, the question "how old was I then?" is answered in place, without leaving the page. It never annotates the dates on a page on its own.
Appears only on selection
A small "See age" button appears only when the whole of your selection can be read as a date. Ordinary selecting and copying are left alone.
Your family, side by side
Register up to five people, yourself included. Their ages on that day line up at once, and anyone not yet born is shown as "Not born yet".
Era, weekday, and distance
When the date is precise enough, it also shows the Japanese era year, the weekday, and how far the date is from today.
No external sending
Birth dates stay in this browser and are never synced. The extension has no network permissions and no means of sending anything anywhere.
PEOPLE & SETTINGS
What you register, and what you can change
Only a display name and a date of birth. No full names, no relationships, no accounts. Settings are stored on your device.
Registering people
A display name and a date of birth, for up to five people including yourself. You can also choose a colour and an order, and show or hide each person in the result.
What the result card shows
The Japanese era year, the weekday, the distance from today, and the date of birth can each be turned on or off. Everyone’s age is always shown.
Showing dates of birth
By default the result card also shows the birth dates you registered. You can turn this off before sharing your screen. What the "Copy" button writes out never includes a birth date.
Calendar
A Japanese interface shows the Japanese era year; other languages show the Gregorian date only. You can also set it manually.
ON / OFF
Turn it off and nothing appears on web pages at all. Toggle any time from the toolbar popup.
Display language
Auto-selected by your browser language.
Compatibility
Works on any web page, in the latest version of Google Chrome.
HOW IT WORKS
Select a date. That is all.
It responds only when the whole of your selection reads as a date. What cannot be stated definitively is not stated definitively.
Select a date
Drag to select a date on the page. The "See age" button appears only when the whole selection can be read as a date.
It does not react to things that are not dates, like "1,980 yen" or "03-1234-5678" — nor to a date merely sitting inside a longer sentence.
See the ages on that day
Press the button and everyone you registered lines up with their age. The era year, weekday, and distance from today appear according to how precise the date is.
A year-only or month-only date gives a range (e.g. 19–20), because rounding something undetermined into a single number would be inventing a fact.
Dismiss or copy
Press Escape, or the close button, and the card disappears. "Copy" writes out the result you can see.
What you copy is never stored and never sent anywhere. Birth dates are not included.
GET STARTED
Install & use
Add it, open it from the toolbar, and reach settings in a click.
1Install
Just press “Add to Chrome” on the Chrome Web Store.
2Pin to the toolbar
Open the extensions icon (the puzzle piece) at the top-right of Chrome and pin Find My Age so it’s always one click away.
3Register people
On the settings page, start by entering your own display name and date of birth. You can add family members later, up to five in total.
4Select a date and check
Select a date on any web page and press the "See age" button that appears — a card lines up everyone’s age on that day.
Open it any time from the extensions icon (the puzzle piece) at the top-right of Chrome.
PRIVACY
Our privacy promise
A date of birth deserves the quietest handling of anything you could entrust to a tool. So this one never takes it anywhere.
The birth dates you register stay in this browser, and are never synced.
It reads only the text you selected, and discards it the moment it has decided whether that text is a date.
Where data lives
The people you registered (display name, birth date, colour, order, visibility) and your settings are kept in chrome.storage.local. Synced storage (chrome.storage.sync) is deliberately not used — that would upload dates of birth to Google’s servers.
What is never stored
The URL, body text, and headings of pages you visit, the text you select, the results shown, and anything you copy. None of it is recorded. Browsing history, cookies, credentials, and location are not collected either.
External traffic
No server, no analytics, no telemetry. There are no network-related permissions, and the extension has no means of sending anything anywhere.
Permissions needed
Access to all sites exists because a date can appear on any page. It reads only the range of text you selected; it does not collect, record, or transmit page content. Beyond that it uses only settings storage (storage).
Frequently asked questions
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How old were we on that date?
Free and fully on-device. Add it to Chrome and start using it today.
View on Chrome Web StoreLEGAL
Before you start
Our privacy promises and usage rules are collected in the documents below.