---
title: "About Past Crumbs | Past Crumbs"
description: "What Past Crumbs is: free tools for family historians, students, teachers and writers working with old dates, calendars, Roman numerals and old money."
url: https://pastcrumbs.me/about/
---

# About Past Crumbs

Small, free tools for the dates and sums you meet in old documents.

## What it is

Past Crumbs is for family historians, history students, teachers, writers and anyone reading old papers. It answers the questions that trip people up: what day of the week a date fell on, why a letter is dated 1720/21, which calendar a country was using, when Easter fell in a given year, what MDCCCCX means and what £1 2s 6d is in today's money.

## How it works

Everything runs in your browser. The calendar rules, tables and formulas are part of the page, so nothing you type is sent anywhere, and once a page has loaded it keeps working without a connection. Your timeline and your light or dark theme choice are kept in your browser's local storage on your device and nowhere else. There are no accounts, cookies or ads; page views are counted by Cloudflare Web Analytics, as the privacy page explains.

## Accuracy

Conversions go through the Julian Day Number, using the algorithms in Jean Meeus's *Astronomical Algorithms*. Our tests check them for every day from 1 to 9999 CE, by counting the days and against a second published method (Fliegel and Van Flandern, 1968); Easter dates are checked against a second algorithm for every year from 1583 to 9999. Every page ends with its sources, linked where they are online, and anything we could not trace to a named source has been left out. Gregorian dates before 15 October 1582 are marked as proleptic, since nobody wrote them that way at the time.

## What it does not do

It converts between the Julian and Gregorian calendars only. Regnal years, other religious calendars and the many local ways of starting the year are not converted, and the old money converter gives face value, not buying power.