How is the score calculated?

Your score is 100 minus the area gap between the two pieces, shown to two decimals. A 49:51 split has a 2% gap and scores 98.00%; a line that misses the shape scores 0%.

What score do I need for each grade?

S is 95% or more, A is 85%+, B is 70%+, C is 50%+ and D is below 50%. In split terms, an S means the smaller piece holds at least 47.5% of the area.

How do I draw the cut on a phone?

Drag with your finger and lift it to cut. The line extends past both ends of your drag, so you only need to set its position and angle; very short drags are ignored so you can try again.

Is there a trick to cutting a shape in half?

Yes — find the shape's balance point (centroid). On a convex shape, any line through the centroid leaves each piece at least 4/9 of the area, which already scores 88.89% or more.

Mini Games

Bisect

Split a shape into two equal areas with one straight line. A one-shot precision game scored to 0.01%.

How to play

Tap Start. A random shape appears in the play area.
Drag in any direction to draw a straight line. It extends past both ends, so only its position and angle matter.
Release to cut. Each piece shows its share of the area; your accuracy is 100 minus the gap.

My Best

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Aim for a Perfect Split!

Ranking

Rank	Nickname	Score	Detail	Date

Rank	Nickname	Score	Detail	Date
-	You	-	-	-

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Bisect gives you one random shape and one cut. Drag a straight line across it, let go, and the game splits the shape and prints each piece's share of the area. Your accuracy is 100 minus the area gap, to two decimals — a 49:51 split scores 98.00%, a perfect 50:50 scores 100%.

There's no ruler, no grid and no time limit, so you can study the shape as long as you like before committing. Every shape is a freshly generated convex polygon, so you can't memorise answers. The line runs past both ends of your drag, which means only its position and angle matter; a line that misses the shape scores 0%. Your best score is recorded on the ranking, and a challenge link lets a friend try to beat it.

A useful fact for this game: on a convex shape, any line through its balance point (centroid) leaves each side with at least 4/9 of the area. Aim through the centroid and you're guaranteed at least 88.89% — an A — before fine-tuning the angle.

Frequently Asked Questions

Q. How is the score calculated?
A. Your score is 100 minus the area gap between the two pieces, shown to two decimals. A 49:51 split has a 2% gap and scores 98.00%; a line that misses the shape scores 0%.
Q. What score do I need for each grade?
A. S is 95% or more, A is 85%+, B is 70%+, C is 50%+ and D is below 50%. In split terms, an S means the smaller piece holds at least 47.5% of the area.
Q. How do I draw the cut on a phone?
A. Drag with your finger and lift it to cut. The line extends past both ends of your drag, so you only need to set its position and angle; very short drags are ignored so you can try again.
Q. Is there a trick to cutting a shape in half?
A. Yes — find the shape's balance point (centroid). On a convex shape, any line through the centroid leaves each piece at least 4/9 of the area, which already scores 88.89% or more.