Free Online HIIT Timer

Choose a preset (Beginner, Standard, Advanced, or Endurance) or set custom values for work, rest, rounds, warm-up, and cool-down. Press Start and the timer handles everything — warm-up first, then a 3-second Get Ready countdown, followed by alternating work and rest intervals for all rounds, and finally cool-down.

Phase colors: Red for Work, green for Rest, amber for Warm Up and Get Ready, blue for Cool Down. The round badge shows your progress (e.g., "Round 3 of 8"). No rest plays after the final work interval — the session moves directly to cool-down.

Presets: Beginner (20/20 x 6) uses a 1:1 ratio with shorter rounds for those new to HIIT. Standard (40/20 x 8) is the default — a 2:1 ratio that balances effort and recovery. Advanced (45/15 x 10) pushes the ratio to 3:1 with more rounds. Endurance (60/30 x 6) uses longer intervals with a 60-second warm-up and cool-down.

Controls: Space to start or pause, R to reset, Escape to stop. All settings save automatically and persist across sessions.

HIIT (High-Intensity Interval Training) is a training method that alternates between short bursts of intense exercise and recovery periods. Work intervals are performed at near-maximum effort — typically 80–95% of your maximum heart rate — while rest intervals allow partial recovery before the next round.

The defining feature of HIIT is the intensity, not the specific timing. Work periods can range from 10 seconds to several minutes, and rest periods vary from complete rest to light active recovery. What matters is that work intervals push you to near-maximum effort.

HIIT is used across fitness, sports training, and rehabilitation. It works with bodyweight exercises, cycling, rowing, running, kettlebells, and any activity where you can rapidly switch between high and low intensity.

Tabata is a specific HIIT protocol: 20 seconds work, 10 seconds rest, 8 rounds (4 minutes total). It was developed by Dr. Izumi Tabata for Olympic speed skaters and follows a fixed 2:1 work-to-rest ratio.

HIIT is the broader category. Work and rest durations vary widely — from 10-second sprints with 60-second recovery (1:6 ratio) to 60-second efforts with 15-second transitions (4:1 ratio). Round counts, warm-up phases, and cool-down periods are all customizable.

Use the Tabata timer when you want the classic 20/10 protocol. Use this HIIT timer when you need flexible work/rest ratios, warm-up and cool-down phases, or presets matched to your experience level. For fully customizable intervals without HIIT-specific presets, try the interval timer.

Always warm up. HIIT demands maximum effort from the first work interval. The built-in warm-up phase (default 60 seconds) gives you time to prepare your muscles and cardiovascular system before high-intensity work begins.

Match the ratio to your goal. A 1:1 ratio (equal work and rest) builds aerobic endurance. A 2:1 ratio (e.g., 40s work / 20s rest) is standard HIIT. A 3:1 or higher ratio builds anaerobic power but demands strong conditioning.

Prioritize form over speed. As rounds progress and fatigue sets in, maintain proper technique. Choose exercises where form holds up under fatigue — squats, kettlebell swings, and cycling are safer than complex movements.

Allow recovery between sessions. Schedule 48 hours between HIIT workouts to let your body recover. Two to three HIIT sessions per week is sufficient for most people. Use a countdown timer for standalone warm-up or cool-down sessions.