Reading an evaluation bar.

What the bar measures

An evaluation bar shows an engine's estimate of who is better, and by how much, if both sides played on well. White's share grows from the bottom, Black's from the top; the middle line is level. The number beside it says the same thing in figures.

Pawns as a unit

Numbers are in pawns, from White's side. +1.0 means White is better by about the value of a pawn; -3.0 means Black is better by about a piece. Engines count in hundredths of a pawn, called centipawns, so you may also see 100 for one pawn.

Engines do not all scale their numbers the same way. Some, used by other chess apps and sites, turn them into winning chances rather than counting material, so +1.0 there means roughly an even chance that White goes on to win. Arasan, the engine in Plyfolio, scales them its own way. So the same figure can mean a little more or less from one app to another. Either way, +1.0 is a real advantage, but it is not a win.

Mate scores

When the engine finds a forced mate it stops counting pawns and shows the number of moves to mate instead, such as M5. A minus sign means Black is the one mating. The bar fills completely.

Why it swings

In quiet positions the bar barely moves. In sharp ones, a single move can swing it from +2 to -2, because one tactic changes everything. The bar also shifts as the engine looks deeper: an evaluation at depth 12 can change at depth 24. Plyfolio shows the depth with every number.

When to ignore it

• When the line behind the number is one no human would find. The bar assumes perfect play.
• In time trouble positions: a +3 position with ten seconds on the clock is not +3 for you.
• In the opening, where small numbers mean little.
• While you are still forming your own view. Look at it last.

Written 4 November 2026. The words for each range are Plyfolio's own and are a guide, not a standard; engines and sites word them differently.