Your most impactful Web Vital

Google is about to begin using Core Web Vitals as a ranking factor. So here’s a friendly reminder for everyone that network payload a.k.a. page weight a.k.a. page size is the most impactful metric on your Lighthouse report – even if it’s not deemed a Core Web Vital by Google.

Because of page size, a child in the U.S. – or anywhere – may have to choose between eating lunch or doing homework. Here is why…

Page size and cost

The median website weighed 2.4MB in 2020. This translates into 20 cents per page load on a cheap U.S. pre-paid plan. Cheap – that’s a best case scenario.

By the way, does it surprise you that countries like the United States, Switzerland, Ireland, or Canada lead the cost graph above?

Switch to the Cost as % of GNI tab and it almost literally flips over.

Those 20 cents per page equate to 0.13% of a person’s daily income in the U.S. and now appear way further down the list. Check out the other countries, too.

Core Web Vitals vs real life

In Mauritania (at the top of the graph above) a person would pay the equivalent of €2 in purchasing power compared to a person in Germany, or $2.3 in the United States, just to open one (1) page on an average website.

If you’re in Mauritania and you make $15 a day, I wonder how vital a Google-pleasing LCP below 2.5 seconds may feel compared to the fact the same page is burning roughly $1 per second of load time? Writing this article would have cost me more than a week’s income.

Lunch, or homework

Now, back to that child in the U.S. and their homework. 0.13% of a person’s daily income per page view may sound little until you put it into perspective (which is what I learned you’re supposed to do with numbers, otherwise they’re useless). So let’s look at how much folks in the U.S. spend for, say, groceries.

Weekly grocery expenses of a U.S. household with children under 18 averaged $160 in 2020.

That’s about $23 per day to feed a family.

For sake of example, let’s assume a household of three, including one child under 18, who eat three meals a day. Let’s also ignore price differences in those meals as well as differences in individual eating habits:

$23 daily grocery expenses 
÷ 3 humans 
÷ 3 meals 
= $2.55/person/meal/day

So on average, a child on a pre-paid plan in the U.S. can eat lunch, or spend the equal amount of money visiting 12 web pages to do their homework.

And there you have it: page size – not a Core Web Vital according to Google, but still your most impactful and, dare I say it, empathetic web performance metric.

Page weight and carbon

Note that I haven’t even dipped into environmental cost. Clearly, other factors, like servers powered by renewable energy, have a much bigger impact on carbon emissions initially. But once you start comparing equally “green” infrastructure, megabytes sent over the wire by a web page start to matter again.

According to Website Carbon Calculator, the average web page tested on their site “produces 1.76 grams CO₂ per page view. For a website with 10,000 monthly page views, that’s 211 kg CO₂ per year”.

For your perspective, four of those websites generate the yearly CO₂ emissions of one Mauritanian. And that’s another post for another time…