What an online chess clock is for

A chess clock is two countdown timers sharing one rule: only the side whose turn it is runs down. Originally invented in 1883 for over-the-board (OTB) chess, the same mechanism now powers debate timing, Magic: The Gathering tournaments, blind chess variants, and any two-party turn-based activity where each side gets a fixed budget.

This page gives you a fully featured clock in your browser — no app to install, no physical clock to buy, no Bluetooth pairing.

Time controls explained

• Base time — the total seconds each player gets at the start (e.g. 5 minutes for blitz)
• Fischer increment — adds time after every move you make. The clock can grow. Default in online chess.
• Bronstein delay — adds time after every move, but only up to what you actually spent. The clock can never grow above the base. Standard at elite OTB tournaments.
• Simple delay — the clock pauses for X seconds at the start of each move before running. Used in US Chess events.

For a non-chess use (e.g. debate or board games), Fischer is usually what you want: it rewards quick play without ever penalising a careful think.

Built-in presets

Bullet 1+0, Bullet 2+1, Blitz 3+2, Blitz 5+0, Rapid 10+0, Rapid 15+10, Classical 30+30, Debate 3-minute. One tap loads any of them.

Why use this over a physical clock

• It's in your pocket. Any phone or tablet is now a tournament-quality clock.
• No drift. Mechanical clocks drift; this one uses your device's wall-clock timestamp.
• Flag-fall detection. When time runs out, the clock beeps and announces the winner — no arguments about who flagged first.
• Two-tap mode. Each side taps their own panel to switch. Or use A / L hotkeys for desktop.