About

The Tabata protocol prescribes 20s of maximal effort followed by 10s of rest, repeated for 8 cycles. Total elapsed time per set equals 4min. Deviating from prescribed intervals degrades the metabolic response. A 2s overshoot on rest periods across 8 cycles adds 16s of unearned recovery, reducing peak oxygen deficit by an estimated 8 - 12%. This timer uses drift-corrected intervals and audible phase-change cues to enforce strict adherence. Configure work duration T_w, rest duration T_r, cycle count n, and set count S to match standard Tabata or any custom HIIT protocol. Note: caloric estimates require heart-rate data not captured here. This tool handles timing precision only.

Formulas

Total workout duration T_total is computed from the configured parameters:

T_total = T_prepare + S × (n × (T_w + T_r)) + (S − 1) × T_rest-set

Where T_prepare = preparation countdown in seconds, S = number of sets, n = cycles per set, T_w = work interval duration, T_r = rest interval duration, and T_rest-set = rest period between sets. The work-to-rest ratio is expressed as T_wT_r. For classic Tabata this yields 2010 = 2:1. Timer drift correction applies a delta: t_corrected = t_expected − (t_actual − t_expected), ensuring accumulated error stays below 16ms per tick.

Reference Data

Protocol	Work	Rest	Cycles	Sets	Total Time	Work:Rest Ratio	Intensity
Classic Tabata	20s	10s	8	1	4min	2:1	Maximum
Standard HIIT	30s	30s	10	1	10min	1:1	High
Sprint Intervals	15s	45s	8	2	16min	1:3	Maximum
Beginner HIIT	20s	40s	6	1	6min	1:2	Moderate
Little Method	60s	75s	12	1	27min	4:5	High
Gibala Protocol	60s	60s	10	1	20min	1:1	High
Zuniga Protocol	30s	30s	16	1	16min	1:1	Very High
Meyer Protocol	30s	15s	13	1	9.75min	2:1	Very High
Boxing Rounds	180s	60s	12	1	48min	3:1	High
CrossFit EMOM	40s	20s	10	1	10min	2:1	High
Kettlebell Swing	35s	25s	10	2	20min	7:5	High
Rowing Intervals	45s	15s	8	3	24min	3:1	Very High
Cycling Sprints	10s	50s	6	3	18min	1:5	Maximum
Active Recovery	25s	35s	8	1	8min	5:7	Low
Endurance Build	90s	30s	6	2	24min	3:1	High

Frequently Asked Questions

Dr. Izumi Tabata's 1996 study at the National Institute of Fitness and Sports in Tokyo tested this specific ratio on Olympic speed skaters. The 2:1 work-to-rest ratio at 170% of VO₂max produced simultaneous improvements in both aerobic (VO₂max increased by ~14%) and anaerobic capacity (~28% improvement) over 6 weeks. Altering the ratio shifts the metabolic demand - longer rest shifts toward phosphocreatine recovery, shorter rest risks form breakdown before completing all 8 cycles.

JavaScript's setInterval is not guaranteed to fire at exact intervals. Browser tab throttling, garbage collection, and rendering can delay callbacks by 10-50ms per tick. Over 8 cycles of 30-second intervals, uncorrected drift can accumulate 400ms+ of error. This timer records the actual elapsed time via Date.now() at each tick and adjusts the next interval delay to compensate, keeping cumulative drift under 16ms - the duration of a single animation frame at 60fps.

A 1:1 ratio (e.g., 30s work / 30s rest) allows approximately 50% phosphocreatine resynthesis during rest, sustaining moderate-to-high power output across cycles. A 2:1 ratio (e.g., 20s work / 10s rest) permits only ~25% resynthesis, forcing greater reliance on anaerobic glycolysis. This produces higher blood lactate concentrations (typically 12-15 mmol/L vs. 8-10 mmol/L) and greater excess post-exercise oxygen consumption (EPOC), which increases caloric expenditure for 24-48 hours post-workout.

Yes. Configure the work period to 180s and rest to 60s for standard 3-minute boxing rounds. For EMOM (Every Minute On the Minute), set work to your target completion time (e.g., 40s) and rest to the remainder of the minute (20s). The timer supports work durations from 5 to 300 seconds, rest from 1 to 120 seconds, up to 50 cycles per set, and up to 10 sets with configurable inter-set rest.

Auditory discrimination during high-exertion exercise relies on frequency separation. This timer uses ~600Hz (higher pitch) for work-start cues and ~440Hz (lower pitch) for rest-start cues - a separation of approximately a musical fifth. Research in exercise psychoacoustics shows that frequency gaps above 200Hz are reliably distinguished even when heart rate exceeds 85% of maximum and auditory attention is impaired. The 3-2-1 countdown beeps at 800Hz provide additional anticipatory cuing.

Direct measurement requires indirect calorimetry. Estimates range from 240-360 kcal per 4-minute session when including EPOC. However, this depends on body mass, exercise selection (burpees vs. air squats), and individual VO₂max. This timer does not estimate caloric expenditure because doing so without heart-rate or oxygen-consumption data would produce errors of ±40% or more. Use a chest-strap heart rate monitor paired with a validated metabolic equation for meaningful estimates.