cero

FREE TOOLS

Online boxing round timer

Rounds and rest for boxing, MMA and Muay Thai, with a warning before every bell, free in your browser

Interval timer

Ready when you are

03:00

Keep this tab open and in front: browsers can slow down timers in background tabs. The Cero app keeps going with your screen locked, on your Apple Watch and in the Dynamic Island.

How to use it

  1. Pick a preset, or set your own round length (work), rest and number of rounds, in seconds.
  2. Press Start: you get 10 seconds to get your gloves on.
  3. Three short beeps warn you before each bell, so you can finish strong.
The presets.
PresetRoundRestRounds
Amateur3 min1 min3
Pro3 min1 min12
2-minute rounds2 min1 min10
MMA5 min1 min5

For Muay Thai, set 180 seconds of work and 120 of rest for 5 rounds. See how long a boxing round is in each sport.

Session ideas

  • Heavy bag: 6 rounds of 3 minutes.
  • Shadowboxing: 3 rounds to warm up.
  • Skipping between rounds: use the rest minute for a minute of jump rope.

YOUR NEXT SESSION STARTS HERE

Bring the effort.
We’ll keep the time.

Cero is free to download for iPhone, iPad and Apple Watch.

Download Cero
Cero’s Gym Display on iPhone: HIIT 30/15, high intensity, set 2 of 8, 4:31 remaining, low intensity next, and a Show on TV button

Cero is a timer, not a medical device. If you’re new to hard exercise, are pregnant or have a health condition, check with your doctor first, and stop if you feel unwell.