Count on NIST to Provide Well-Measured Holiday Cheer

Credit: B. Hayes/NIST

’Tis the season to be … measure-y? 

During the holiday season, we measurement geeks can’t help but ask — and seek the answers to — some very important holiday-related questions.

How long would it take Santa to visit every household in the U.S. with a child under the age of 18 if he spent approximately five minutes delivering presents to each house?

According to the Census Bureau, there were approximately 33.3 million households in the U.S. with children under the age of 18 in 2024. (We realize we are overcounting here because not all households celebrate Christmas, but since we don’t have data that granular, we’ll use what we have.)

Assuming the five-minute delivery window mentioned above — and we realize that’s REALLY fast given he has to land, get inside the house, take out the present(s), lay them under the tree, eat cookies, drink milk, exit the house, get back in the sleigh and take off. But we’re giving Old St. Nick the benefit of the doubt that he’s a fast guy.

So at five minutes per house, we’re looking at:

• Approximately 166,500,000 — or 166.5 million — minutes
• Or 9,990,000,000 — 9.99 billion — seconds (We wanted to figure out the seconds since it’s the base unit in the metric system.)
• Which equals 2,775,000 — 2.775 million — hours
• Or 115,625 days
• Or ~16,518 weeks
• Or ~3,801 months
• Or almost 317 years!

And that doesn’t even include the time it will take him to travel between the different houses! Given that Santa manages to deliver not just to the U.S., but to the whole world, in 24 hours … well, we can only assume that Santa is clearly quantum and can do “spooky” things that us regular humans can only imagine.

How much would Santa’s sleigh weigh if every U.S. child under the age of 18 got one book for Christmas?

There were about 73.1 million children under the age of 18 in the U.S. in 2024. (Shout out to our Commerce buddies over at the U.S. Census Bureau for these stats!) 

It’s time to do a little mathing again.

Books obviously have varying weights. Per our research, they can be as light as 113 grams (think mass market paperback) or as heavy as 1.36 kilograms (we’re talking about you, hardcover books). Children’s picture books fall in the middle, but closer to the mass market paperback end of the spectrum. So for the ease of calculations, we’re going to just split that down the middle, which gives us about 737 grams, or 0.737 kilograms. 

And doing the math, that gives us about 53,800,000 kilograms, or 119 million pounds. That’s a LOT. (In fact, one estimate is that it’s about half the weight of an aircraft carrier!)

Side note, and a quick measurement science lesson: Kilograms are a unit of mass, while pounds are a unit of force. Pounds express how much gravity pulls on a mass, like books (or a human body on a scale). The more mass something has, the more pounds it weighs. So, while they aren’t exactly the same thing, people generally consider it acceptable to convert between the two. When we do so, we usually assume a fixed value for the strength of gravity on the Earth’s surface for simplicity. So, for our friends who are not as well versed in metric, our average book mass of 737 grams would be about 1.5 pounds.

How many reindeer would it take to pull Santa’s sleigh with all those books in it?

Fun fact I found out while working on this blog post: Reindeer are pretty strong creatures. No wonder Santa chose them (over, say, Alaskan huskies) to pull his sleigh. Reindeer can pull a load of up to 300 pounds (136 kilograms) at an average of 8 miles (or 13 kilometers) per hour.

But clearly, as we calculated above, even with minimal cargo, we’re a bit over that 300-pound number. We’re even significantly above what all nine of Santa’s reindeer could pull! 

So how many reindeer would Santa need if we were in the world of normal physics? About 400,000! (We’d all need to buy a LOT more carrots if we had to provide fuel for that many reindeer on Christmas Eve!)

Thank goodness Santa and his reindeer are clearly working in the world of quantum physics, both in terms of super strength AND super speed.

If Santa limits himself to one cookie at each house he visits in the U.S., how many kilograms of cookies will he have eaten? 

So once again using the data from our colleagues at the U.S. Census Bureau, there were approximately 33.3 million U.S. households with children under the age of 18 in 2024. 

Like books, Christmas cookies obviously can have a variety of weights. But the average Christmas cookie weighs anywhere from 0.015 to 0.060 kilograms, or 15-60 grams. 

So that means Santa will be eating at least 33.3 million cookies, equal to between 200,000 and 500,000 kilograms, or somewhere between 440,000 and 1.1 million pounds!

And that’s not even accounting for the extra grams that happen when he dips them in milk. Or the times that he sneaks a second cookie because the first one was so good!

We thought about trying to convert that into weight gain, but a) we’re not into body shaming , and b) it’s not a straight calculation since how food converts to weight depends on numerous factors, including current weight, metabolism, ingredients in the cookies, and muscle mass … not to mention the balance of all the exercise Santa is doing that night getting in and out of the sled.

How much oil would you need to keep a menorah burning 24/7 for all of Hanukkah?

How much oil is needed to keep a menorah lit and burning all day and night for eight days, barring any miracles? (Bring on the math, folks!)

According to my research, a typical menorah cup would take 1-2 ounces of oil (about 30-60 milliliters) and would allow one candle to burn for 90 minutes. 

So going with the 90 minutes …

• You would have to fill one cup 16 times to keep the candle burning for one day. So that’s 16-32 ounces (about 480-960 ml) on Day 1.
• But on Day 2, you need to burn two candles. So for Day 2, you’re talking 32-64 ounces (960-1,920 ml).
• Day 3: 48-96 ounces (1,440-2,880 ml)
• Day 4: 64-128 ounces (1,920-3,840 ml)
• Day 5: 80-160 ounces (2,400-4,800 ml)
• Day 6: 96-192 ounces (2,880-5,760 ml)
• Day 7: 112-224 ounces (3,360-6,720 ml)
• Day 8: 128-256 ounces (3,840-7,680 ml)

Which comes out to a grand total of about 600-1,200 ounces, or about 18-36 liters. For those wondering what that would mean for your budget: Assuming you have a membership at a big-box store and can buy your olive oil in bulk, the oil would cost you somewhere around $140-$230 plus tax.

Please note: This question was just a thought experiment. We are an organization that studies fire and cares a lot about safety. Even if you have enough oil to do so, you shouldn’t leave your candles burning 24/7 for eight days. It’s a safety concern for a lot of reasons. Besides, tradition says you should only leave the candles burning for 30-90 minutes, depending on which day of Hanukkah it is.

How many lumens are the lights on the Rockefeller Center Christmas Tree?

Lumen is a way to measure the brightness of light. 

The Rockefeller Center Christmas tree in New York City is decorated with more than 50,000 LED lights and a Swarovski star. (Fun facts: The second official Rockefeller tree, in 1933, only had 700 lights! And when the tree first went to LEDs in 2007, it only had 30,000 lights. We’ve come a long way, baby!) 

So how bright are all those lights and the star?

Being NIST, we tried to be super accurate on this one. We reached out to both Rockefeller Center and the manufacturer of the actual lights used on the tree to try and get more information about the lumens for the specific lights used. Unfortunately, the manufacturer was not able to share that information, and Rockefeller Center did not respond.

That left us having to make some assumptions. (Sorry, science!)

We’re pretty sure the lights are faceted, and it looks like there are two main “models” — C7 and C9 — of commercial grade faceted LEDs. C9 bulbs are larger and brighter, and more often recommended for “large outdoor trees,” so we decided it’s safe to assume the C9 bulb has closer luminosity to what is used on the Rockefeller tree.

The tree has six colors of bulbs — red, orange, yellow, blue, green and cool white — and each color actually has its own luminosity. But we couldn’t find exact luminosity numbers for individual colors. Instead, we could only find a range of 80-120 lumens for commercial C9 bulbs. 

So using that range, we’re looking at 4-6 million lumens for the bulbs. Then there’s the Swarovski star, which is documented as shining at 106,000 lumens. So combined, we’re looking at a potential total of 4.1-6.1 million lumens.

If you’re wondering how bright that is, a modern LED car headlight is anywhere from 1,000-4,000 lumens. So using the middle of the range — 5,106,000 — the luminosity of the Rockefeller tree may be comparable to approximately 638 cars shining their headlights (assuming the brightest headlights and two headlights per car) or the brightness of large stadium lights.

We could keep going here. We had a lot of other questions ready to mathify, like: 

• How much thrust would you need to get Santa’s sleigh filled with the books mentioned above off the ground? (And do you think Santa somehow surreptitiously calibrates his reindeer’s thrust using items calibrated by NIST’s million-pound deadweight machine to ensure that they can get off the ground? Or is that not necessary because, as we mentioned above, the reindeer are quantum?)
• How much heat would the infamous animated yule log put off were it real?
• How much processing power would be needed for Santa’s GPS to quickly calculate the best route to visit every house — a problem that may be best put on hold until quantum computers are in practical use?

But instead of answering those questions — and keeping you online when you could be celebrating the season with your family and friends — we’ll just say: Happy Holidays and Happy New Year.