Idle Game Number Abbreviations: K, M, B, T, aa, ab Explained

In idle games, K means thousand, M million, B billion and T trillion. Each step is 1,000 times the one before. After trillion, games split into three styles: short names for the -illions (q or Qa for quadrillion, Q or Qi for quintillion and so on), letter pairs (aa, ab, ac…) where each new pair is another ×1,000, or scientific notation like 1.5e18. They all describe the same numbers, just written differently.

The chart below covers all three, plus the exact scheme Frog Pond uses.

What do K, M, B and T mean? #

These four are the same in nearly every game:

So 4.2B is 4,200,000,000, and 380T is 380,000,000,000,000. Each abbreviation adds three zeros, which is why the number in front never goes above 999 before the letter changes.

What comes after trillion in idle games? #

Games that stick with names use the English “short scale”, where each new -illion is 1,000 times the last. The values come straight from the standard list of names of large numbers:

The trouble is that quadrillion and quintillion both start with Q, and sextillion and septillion both start with S. Games solve this in different ways. Some use two letters (Qa and Qi, Sx and Sp). Others use case, with lowercase for the first and uppercase for the second.

What notation does Frog Pond use? #

Frog Pond uses single letters and tells the pairs apart by case:

Past undecillion, it switches to scientific notation, so a number like 1.23e+39 means 1.23 × 10³⁹. Small q is a thousand times smaller than capital Q, so it’s worth a second look when you’re reading costs late in a run.

What do aa, ab and ac mean? #

Letter-pair notation, sometimes called alphabet notation, avoids -illion names altogether. After the familiar K, M, B and T, the game starts counting with two letters: aa, ab, ac and so on through az, then ba, bb, and onward. Each step is another ×1,000.

A typical scheme starts aa right after trillion:

Not every game starts at the same place, so treat this as a guide rather than a rule. The easy check is to compare two prices in the game: if one reads 999ab and the next reads 1ac, you know each letter step is ×1,000. The advantage of letter pairs is that they never run out of short labels, and the letters themselves tell you which number is bigger, since ab comes after aa like words in a dictionary.

What does e+ mean in a game? #

That’s scientific notation. The number after the e is the power of ten. So:

• 1e3 = 1,000
• 2.5e6 = 2,500,000
• 7.8e45 = 7.8 × 10⁴⁵, a 7 and 8 followed by 44 more zeros

Many idle games switch to it once their named abbreviations run out, and some let you choose it in settings from the start. Some also offer engineering notation, which keeps the exponent a multiple of three (like 12.5e18) so it lines up with the -illion names.

Why are there so many different systems? #

Because there’s no standard, and each one trades off something. Names are familiar to start with but get obscure past decillion. Letter pairs are compact and unlimited but tell you nothing until you learn them. Scientific notation is exact and universal but looks like homework to some players.

There’s also a regional wrinkle. English uses the short scale, where a billion is 10⁹. Many other languages use the long scale, where a billion is 10¹², a million millions. Idle games written in English almost always use the short scale.

How do you compare big numbers quickly? #

1. Compare the suffix first. A higher suffix always wins, whatever the number in front. 1T beats 999B.
2. Then compare the number. Within the same suffix, 450Q beats 80Q.
3. For scientific notation, compare the exponent. 1.1e40 is ten times 1.1e39.
4. Count in steps of three. Each suffix step is 1,000 times bigger. Three steps apart means a billion times bigger.

Is there a biggest number an idle game can show? #

Most games store numbers in a standard computer format called double-precision floating point, which tops out at about 1.8 × 10³⁰⁸. Past that, the value becomes “infinity”. Frog Pond shows ∞ if a number ever gets there, which in normal play it won’t. A few games, most famously Antimatter Dimensions, make reaching that limit (which it calls Infinity) a goal.

Numbers that big come from stacking multipliers, which we explain in how idle games work. If you’re just starting Frog Pond, you’ll hit your first M within minutes and your first B within the first couple of runs. Our tips for beginners cover getting there quickly, and why idle games are so satisfying looks at why watching those letters change feels so good.

Frequently asked questions #

What does aa mean in idle games? #

In letter-pair notation, aa is the first step after the named abbreviations end, usually 10¹⁵ (one quadrillion) in games where it follows T. Each next pair (ab, ac…) is 1,000 times larger. Check two in-game prices to confirm where your game starts.

What is Qa vs Qi? #

Qa is quadrillion (10¹⁵) and Qi is quintillion (10¹⁸). Games use the second letter to tell the two Q words apart. Frog Pond uses lowercase q and capital Q instead.

What comes after T in idle games? #

Quadrillion, shown as q, Qa or aa depending on the game. It’s 1,000 trillion, or 10¹⁵.

How many zeros is a decillion? #

33 zeros (10³³) on the short scale used in English-language games.