Several pigeons gather on a pier piling on the Sacramento River in Old Sacramento on Saturday, Feb. 2, 2013.

I don’t know if anyone else has done this, but I’ve attempted to calculate how much prices have gone up since it cost “tuppence a bag” to “Feed the Birds” from the Disney movie “Mary Poppins.” It was a bit of an odd journey given that I was trying to figure out inflation for a currency that changed pretty drastically over the past 114 years, but I think the math makes sense.

I’ve actually crunched the numbers twice over the years. The first time was when I was hosting “Evening Jazz” on Northstate Public Radio in Northern California sometime after 2011. As a volunteer DJ, I was spinning Kurt Rosenwinkel’s take on “Feed the Birds (Tuppence a Bag)” off of “Everybody Wants to be a Cat: Disney Jazz Vol. 1.”

While the song was playing, I wondered to myself what a tuppence was and how much it would be worth in modern times.

It took a while, but I crunched the numbers in between songs and came up with a number that I gleefully shared with listeners during a station break.

Fast forward to last month when I was browsing Threads as part of my social media move away from the site formerly known as Twitter. I came across a post from user andromedacat2016 noting that the original movie was set 53 years before its 1964 release and a modern version with the same time gap would be set in 1970.

The user wondered why that question popped into their head and I replied with my random question about the inflationary impact on the tuppence. Andromedacat2016 asked if I had figured it out, so I decided it was time to do the math again.

This is what I came up with —

So my best guess involved using a Bank of England inflation calculator to estimate how much inflation there was on the tuppence up to decimalization and then calculating the new pence inflation to the current year.

• 2d in 1910 might be 16.12d (£sd) at decimalization in 1971.
• Decimalization would convert that 16.12d (£sd) to 6.7 new pence.
• From there, the 6.7p would grow to 82.3p today — really 83p, due to rounding.

Still a great deal for a bag of crumbs!

As I recall from my long-ago radio shift, I think my 2011 calculation came up with something around 72p. That’s a little higher than my current guess after recent inflation, but it seems to be close.

Attempting to solve this problem was fun but challenging for several reasons:

1. In 2011, I wasn’t sure of the year that “Mary Poppins” was set in. Thankfully, I went with  Andromediacat2016’s date this time out.
2. What the heck was a tuppence? It’s clear now that it’s a variation of “two pence,” but the old pounds, shillings, pence system (£sd) of British currency prior to decimalization in 1971 remains a bit baffling to me. (As an aside, it’s popped up on some 1980s British TV that I’ve watched, including the “Doctor Who” story “Remembrance of the Daleks” and the Britcom “Hi-De-Hi!” which is set at a holiday camp in 1959.)
3. Before I could get to decimalization in 1971, I had to calculate an initial 61 years of inflation. While the Bank of England’s calculator goes back to 1209 (six years before the signing of the Magna Carta!), it only allows input in whole pounds. I may have gone off track at this point, but I started with a single pound to calculate the rate over 61 years and applied it to the tuppence.
4. When I reached decimalization (and looked back on Decimal Day via the BBC), I needed to convert the £sd value to the modern system. While this may be another point where my math may have gone astray, I think it was relatively straightforward to convert the old pence where 240 pence equaled 1 pound to the updated system where 100 new pence equalled 1 pound. At least I wasn’t trying to convert shillings, florins and crowns to decimal.
5. From there, it was back to the inflation calculator to determine how much change there’s been over the past 53 years (again being limited by the fact the calculator only allows input of whole numbers).

While I’m hopeful that my estimate is close, there may be factors I didn’t consider that I welcome someone knowledgable to point out.

It’s certainly possible I goofed somewhere. In its article on the song, Wikipedia apparently uses an inflation template to come up with £1.29 in 2023 pounds, and I’m more than a little curious about how it reached that number. Coincidentally, that figure is closer to my 2011 calculation (adjusted for 12 years of intervening inflation).

In the end, it’s fascinating to think about how money may have changed over time and how much things might have cost 114 years ago. Eighty-nine pence (or £1.29) doesn’t seem like it would go far today, and I wonder how much two pence in 1910 would help the woman after accounting for the cost of the bag and crumbs. Indeed, I think the bag would be the biggest cost without knowing how the woman obtained the bread or subsequently prepared the crumbs.

There’s also value reflecting on the message of the song — that of a beggar woman outside St. Paul’s Cathedral selling a frivolous item ostensibly to benefit pigeons, but it’s really charity to help the elderly woman. In one verse, the lyrics include the line “Their young ones are hungry, their nests are so bare/All it takes is tuppence from you.”

As we saw in the film (and can see in real life), it’s easy for some to turn away from those in need. I know that I don’t personally rise to the occasion every time, but hopefully the tragic beauty of a song such as “Feed the Birds” will push me to reconsider (or find other avenues to help).