E=mc2
Sacrifices in chess are the “nuclear weapons” of the game. Think about it: When an atomic bomb is exploded, matter is converted to energy, according to the famous formula in the title above, and the newly-created energy is released on the real-world target.
In chess, the sacrifice converts material (the “matter” of the chessboard) into energy, which is then released on your opponent’s position. But what’s the equation it follows?
Vukovic suggests (and Purdy agrees) that the conversion formula between material and energy in chess is 3 moves per pawn.
This would mean that if it takes your opponent more than three moves to capture a pawn (and by this I mean moves that do not enhance either his development or his position) then it’s probably not worth you worrying about it, and instead you should direct your attention towards using those three moves he would be giving you to finish your development or (if already complete) launch an attack. And, likewise, you should count all the moves you spend chasing after pawns to be sure you’re not giving away vital time your opponent can use to defeat you.
This equation can help you determine if the proposed sacrifice you are calculating can possibly work out. Even if you can’t calculate it completely to the end, if you can count the important tempos you will gain with the sacrifice, you can gain some comfort that even if you don’t clearly see your way, a count of four moves gained in the attack should be worth the pawn you’re spending to launch it.
This is the guiding principle behind many of the opening gambits, that your opponent will spend at least three moves defending the extra pawn, which would mean that even if the gambit pawn itself proves unrecoverable, there will a pawn elsewhere in the position falling to your accelerated attack.