Size Comparison Game: What It's Called, How It Works, and Where to Play

Short answer: The resize-an-object game from Instagram and Facebook clips is called Size It Up. The original daily version comes from Magnitudle at magnitudle.com/size-it-up. We also built a free version with 300 objects, 44,850 possible levels, no login, and no daily limit that you can play any time: play Size It Up here.

You are scrolling and a clip stops you. Someone drags a grey silhouette bigger and smaller next to a familiar object, locks in a guess, and a ghost outline pops up to show how close they were. A score appears. You open the comments to find the name of the game and see forty people asking the same thing. Nobody answers.

So you search for “size comparison game” and get worksheets for primary school classrooms. This guide fixes that. It gives you the name of the game, explains how it works, compares the best size comparison games you can play for free, and shows you how to get better at guessing sizes.

On this page

• What Is a Size Comparison Game?
• What Is the Resize Game From Instagram and Facebook Called?
• How a Size Comparison Game Works
• The Best Size Comparison Games to Play
• Why Our Size It Up Beats the Usual Alternatives
• Size Comparison Games Side by Side
• Why Guessing Size Is Harder Than It Looks
• How to Get Better at Guessing Sizes
• Using Size Games for Learning
• Sources

What Is a Size Comparison Game?

A size comparison game asks you to judge how big one thing is compared with another. You are given a reference object whose size you can see or already know, and you have to work out the size of something else relative to it. The skill behind it is called visual estimation: judging size, length or quantity by eye instead of measuring.

Most size games fall into one of three families:

1. Resize games. You drag and scale a silhouette until it matches the true size next to a reference. This is the format in the clips going around social media.
2. Number-guess games. You type a length, height or weight and the game tells you how far off you were.
3. Zoom visualizations. Not scored. You scroll or slide from tiny to huge and take in the scale. They are great for building intuition, though they are not games in the strict sense.

Every one of them trains the same thing: your sense of scale, meaning how big things are in relation to each other. That sense is surprisingly easy to lose track of, which is exactly why these games are fun.

What Is the Resize Game From Instagram and Facebook Called?

The name is Size It Up. Magnitudle, a collection of free daily estimation games, describes itself as “the official home of Size It Up” and calls it the original daily visual game. In it you resize a silhouette beside a reference object, then lock in your guess to see the true size.

Magnitudle is an independent project created by a developer who goes by Teej and published through GriddleLink Games. It is free in a web browser, and a new daily puzzle unlocks at midnight in your game timezone.

Our own Size It Up is a separate, independent game with original art and rounds. It is not affiliated with Magnitudle, and we say so on the page. If you are looking for the daily puzzle from the clips, go to Magnitudle. If you want to play as many rounds as you like with no daily limit, ours is built for that.

Which Magnitudle Mode Was in Your Clip?

Magnitudle has more than one game, and short clips look similar. Match what you saw to the mode:

Size It Up also has variants with themes such as pop culture and geography, so if your clip showed fictional characters or maps, it may be one of those.

How to Find the Name of Any Game You See in a Clip

Comment sections rarely answer this, mostly because a short clip does not show the title screen. A few things work better:

• Check the account that posted it. The game’s name is often in the bio, a pinned comment or the profile link.
• Look for a watermark or web address in the corner of the video, especially in the first and last second.
• Describe the mechanic, not the name. Search “game where you resize an object to match real size” instead of guessing the title.
• Screenshot the game screen and run it through a reverse image search.
• Search the platform itself. Instagram and Facebook search reels by caption and hashtag, so try the mechanic words plus “game”.

How a Size Comparison Game Works

The resize format is simple enough to learn in one round:

1. Read the reference. A fixed object, such as the blue one in our game, sits on a ground line. It is the correct size, so treat it as your ruler.
2. Read the name of the target. You are told what you are sizing.
3. Drag and resize. Move the target and scale it with corner handles, pinch gestures, scroll, or keyboard keys.
4. Lock your guess. Press the button and the true size appears as a ghost outline.
5. Get scored. Your score depends on how close you were in ratio, not in pixels.

Scoring is the clever part. In Magnitudle’s Size It Up, a daily game has five comparisons worth up to 100 points each, for a maximum of 500, and an estimate within 6% of the target earns the full 100. Our version uses the same 6% rule for a full 100, treats “twice too big” and “half too small” as equally wrong, and scores five times off as zero.

Scoring by ratio matters because size mistakes are multiplicative. Guessing a tower is twice its real height is the same size of mistake as guessing it is half. That is also why you should not think in “a few centimetres” but in “how many times bigger”.

The Best Size Comparison Games to Play

These are the ones I checked directly. All are free at the time of writing, though availability can change.

Size It Up on iambored.blog

Size It Up is our own game, so take that disclosure into account. A blue reference sits on a ground line and a red target is yours to resize. It has 300 photoreal objects and 44,850 possible levels: every unique pair combination from that catalog (300 × 299 ÷ 2). The odds of randomly landing the same level again are about 1 in 44,850, or roughly 0.0022%. Play those levels in series at 30 seconds each and you need about 374 hours, roughly 15 and a half days straight, before you come back to level 1. Rounds mix everyday objects, landmarks, animals and cosmic scales. A round takes under a minute, you need no account, there is no daily limit, and your best score is saved on your own device. It works with touch, mouse and keyboard.

Size It Up on Magnitudle

The original daily version. Five comparisons a day, up to 500 points, and a new puzzle at midnight in your timezone. It also offers an archive of past puzzles and several related modes, including Weigh It Up for weight. If you like a once-a-day ritual and comparing scores, this is the one. If you want to keep playing after those five rounds, our unlimited version is built for that.

Why Our Size It Up Beats the Usual Alternatives

Magnitudle deserves credit for popularizing the daily resize format. Zoom tools like The Size of Space are excellent for building intuition. Here is why a lot of people who land on those clips still prefer finishing on our Size It Up:

1. No daily limit. Daily puzzles are fun until you finish five comparisons and hit a wall. Ours lets you play another round immediately.
2. No login and no download. Open the page and start. Nothing to install, no email gate, no “create an account to continue.”
3. More possible levels. With 300 cutouts you get 44,850 possible levels. Same-level odds are about 1 in 44,850, and a full series at 30 seconds per level is about 374 hours before you loop back to level 1, so sessions stay varied instead of looping a short daily set.
4. Photoreal cutouts, not just silhouettes. The shapes look like the real things, which helps your brain lock onto the object name and size.
5. Fair ratio scoring you can grind. Same 6% full-score rule people know from the clips, but you can practice for as long as you want and chase a local best score.
6. Works on phone and desktop. Touch drag, corner handles, pinch zoom, mouse, and keyboard. Built for the same mobile-heavy “I’m bored” audience that finds the clips.

Use Magnitudle when you want the official daily ritual. Use ours when you want the same mechanic without the clock, the queue, or the five-round ceiling.

Bananas For Scale

A different take by KlodsGames, described on its itch.io page as “a game about guessing the size of things.” Instead of dragging a shape, you type a number for each item, and the game accepts fractions with a slash, which helps when you want to compare a large object with a smaller one. The page offers a zip download and says to run an .exe file, so it appears to be for Windows. It links to a submission for GMTK Game Jam 2024.

The Size of Space

Not a scored game, but one of the best ways to build scale intuition. It is an interactive page by Neal Agarwal on neal.fun that shows how Earth compares with the Sun, black holes and the Milky Way. You start by swiping left or pressing the right arrow key and then keep going. Play a few rounds of a resize game first, then come here to see how far the scale ladder really goes.

Scale of the Universe 2

An interactive zoom made by Cary Huang when he was 14, with technical help from his twin brother Michael. You use a slider or mouse wheel to move from the smallest features scientists have proposed to the largest, and you can click objects to learn more. ABC News’s write-up described it as running on Flash, so it may not work on every device. Check that the current version loads before relying on it.

If you want the same “how big is that really?” feeling in other forms, our list of 20 sourced facts that sound fake but are true has several scale surprises, and the rest of our free browser games cover reflexes, numbers and logic.

Size Comparison Games Side by Side

Why Guessing Size Is Harder Than It Looks

If you scored badly the first time, you are in good company. A 2025 study from the IPN Leibniz Institute for Science and Mathematics Education had 335 junior high school students complete a length estimation task, with follow-up interviews for 45 of them. The authors reported “moderate length estimation skills,” found that performance did not vary by grade level, and noticed that results changed depending on the size and accessibility of the objects being estimated.

That last point is useful. You are usually good at sizes you handle every day and much worse at things you cannot hold or stand next to, like a skyscraper or a planet. The study was about students, so it cannot tell us how adults score, but the strategies it identified are the same ones that help in a size game: using a benchmark you already know, drawing on prior knowledge, or combining the two. Plain guessing and eyeballing were the weakest approaches described.

How to Get Better at Guessing Sizes

Pick a Benchmark First

Before you touch the handles, ask what you already know that is close in size. The reference object in the game is your first benchmark. The Maths Is Fun page on visual estimation sums up the habit: knowing the usual size of things helps you estimate quickly.

Get the Order of Magnitude Before the Details

Decide whether the target is smaller than, about the same as, or many times bigger than the reference. Settle that before you fine-tune. Most big misses are a wrong order of magnitude, not a few percent.

Learn a Few Anchor Sizes

A short list of verified anchors goes a long way:

Worked Example

Say a round shows a blue whale beside the Eiffel Tower. The tower is about 1,083 feet and the largest blue whales reach up to about 110 feet. Divide 1,083 by 110 and you get roughly 9.8, so stack about ten of the biggest whales nose to tail and you are near the top of the tower. The “ratio” thinking turns a vague picture into a number you can drag toward.

Now try Earth and the Moon. Earth’s diameter is 12,756 km and the Moon’s is 3,476 km (twice its 1,738 km radius). Divide the two and the Moon is about 0.27 of Earth’s width, a little over a quarter. If you picture the Moon as about a quarter the width of Earth, you will land close.

These are my own calculations from the source figures, so treat them as estimates. The point is the method: pick an anchor, work out a ratio, then resize.

Using Size Games for Learning

Teachers and parents can use these games as a warm-up. The authors of the Leibniz study discuss instruction that highlights students’ understanding of size and scale knowledge, and a resize game puts that into practice in a minute or less. Ask players to say their ratio out loud before they lock in (“I think it is about ten times the reference”), then compare it with the reveal. Talking through the reasoning is where the learning happens. If you want a logic warm-up as well, try our riddles and brain teasers, or the numbers side of things in our 2048 strategy guide.

Sources

• Magnitudle and Size It Up on Magnitudle
• Bananas For Scale on itch.io
• The Size of Space, neal.fun
• Scale of the Universe 2 coverage, ABC News
• Junior high school students’ length estimation skills and use of strategies, IPN Leibniz Institute
• Visual Estimation, Maths Is Fun
• Blue whale, NOAA Fisheries
• Eiffel Tower key figures, official site
• Earth facts, NASA