0:15
15 seconds
Interval presets
Press Start to begin
Space pause · R reset · L toggle loop
Space pause · R reset · L toggle loop
| Start time | +15 sec | −15 sec |
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A 15 second timer is one of the most frequently needed short-interval timing tools. It serves as the standard rest period in Tabata training, the basis for HIIT interval sequences, a quick classroom quiz countdown, a heart rate check window, and a benchmark for everything from cricket temperature readings to Times Square billboard slots. This free timer for 15 seconds loads pre-set to 0:15 and sounds an alarm the instant it hits zero.
Two features make this timer particularly useful for interval training: a Loop mode that restarts the 15-second countdown automatically after each alarm — press L or click Loop once and the timer cycles indefinitely — and interval presets that pair a work duration with a 15-second rest period (30/15, 45/15, 20/15, 60/15). Select a preset and the timer alternates between work and rest phases, tracking your round count, so you can focus entirely on the exercise.
For compound durations, the quick-set buttons include 1:15, 2:15, and 5:15 — useful for classroom segments, workout blocks, and timed activities that involve a 15-second component alongside full minutes.
The page opens with 15 seconds ready. The ring is full and the display reads 0:15. No setup needed — one click starts the countdown.
Click the Loop button or press L before starting. The timer restarts automatically after each alarm, counting how many rounds have completed — useful for rest periods during sets.
Click a preset (e.g. 45/15) to run alternating 45-second work and 15-second rest intervals. The phase label and round counter update automatically. Press Reset to end the session.
Click 1:15, 2:15, or 5:15 for timers that combine full minutes with a 15-second tail — used for classroom tasks, quiz rounds, and exercise circuits with non-round durations.
The 15-second rest period is one of the most used intervals in structured fitness training. It appears in several well-established protocols, each using it differently:
| Protocol | Work | Rest | Use case |
|---|---|---|---|
| 30 on / 15 off | 30 sec | 15 sec | HIIT — 2:1 ratio, keeps heart rate continuously elevated. Common in group fitness and app-based workouts. |
| 45 on / 15 off | 45 sec | 15 sec | Circuit training — 3:1 ratio. More muscular endurance than cardio. Standard in CrossFit-style and bodyweight circuits. |
| 20 on / 15 off (near-Tabata) | 20 sec | 15 sec | Modified Tabata — slightly longer rest than the original 10 seconds, reducing intensity while preserving the interval structure. |
| 60 on / 15 off | 60 sec | 15 sec | 4:1 ratio. Prioritises endurance and lactate tolerance. Used for longer exercises like running drills, rowing, or cycling sprints. |
| 1 min on / 15 sec rest (loop) | 60 sec | 15 sec | Common in app-based training programs. The 15-second rest is short enough to maintain metabolic stress across a full session. |
30 seconds on, 15 seconds off is among the most popular interval ratios in online fitness content, appearing in yoga flows, HIIT videos, and Peloton-style classes. The 2:1 ratio keeps the heart rate from fully recovering between efforts, which is what drives the cardiovascular adaptations associated with high-intensity training.
45 seconds on, 15 seconds off is widely used in circuit and strength-endurance workouts. The 3:1 ratio is more demanding muscular than cardiovascular, making it well-suited for resistance exercise and bodyweight strength circuits where the goal is volume rather than pure aerobic output.
For the classic Tabata protocol (20 seconds work / 10 seconds rest × 8 rounds), use our dedicated Interval Timer page, which handles automatic round counting and phase alternation for the exact Tabata specification.
Fifteen seconds is not just a timer duration — it appears as a meaningful measurement window in several scientific and practical contexts.
Count your pulse for 15 seconds and multiply by 4 to get beats per minute. A 15-second count of 15–25 beats indicates a normal resting rate of 60–100 BPM. Trained athletes may count 10–15 beats (40–60 BPM resting).
Count cricket chirps in 15 seconds and add 37 to estimate the temperature in Fahrenheit — this is Dolbear's Law (1897). If you count 30 chirps, the temperature is approximately 67°F. Chirp rate rises with warmth.
The Smith System of defensive driving recommends scanning 15 seconds ahead while driving. At 60 mph that is approximately 1,320 feet (0.25 miles). This lead time provides enough space to perceive and respond to hazards before reaching them.
Normal blood clotting (prothrombin time) takes 11–13.5 seconds. A result of 15 seconds is mildly elevated, suggesting possible coagulopathy or anticoagulant influence. Always interpreted by a clinician with full lab context.
15 seconds of recording at 1 frame per second, played at 30 fps, produces 0.5 seconds of video. At 1 frame per 5 seconds over 15 seconds (3 frames total), playback is a fraction of a second — useful for cloud movement, cooking changes, and plant growth.
A 15-second digital ad slot on a Times Square screen is a standard purchase unit. TSX Entertainment and other operators sell time in 15-second increments across their large-format displays, making 15 seconds the foundational advertising unit at one of the world's most-visited public spaces.
Times Square, New York City receives approximately 50 million visitors per year and is the most-photographed location in the United States. Its digital billboards are among the most visible advertising placements in the world, and a 15-second Times Square billboard slot is the standard unit of digital out-of-home (DOOH) advertising on its screens.
How much is a 15-second ad in Times Square? The cost varies significantly by screen, position, time of day, and season. Here is a general range based on publicly available campaign data and industry reporting:
Standard four-week digital billboard campaigns at Times Square typically run between $5,000 and $25,000 for mid-tier screens at off-peak periods, scaling to $50,000 to $500,000+ for premium placements on landmark screens during high-traffic periods such as New Year's Eve, the holiday shopping season, or major sporting events. The TSX Entertainment screen at 1515 Broadway — one of the most prominent at the south end of Times Square — is among the most expensive, with large-format immersive packages (including wraparound building displays and in-person activations) reportedly reaching seven figures for major brand campaigns.
TSX Times Square 15 seconds pricing follows a similar structure. TSX operates a large LED screen integrated into its retail and entertainment complex, allowing brands to pair digital display with experiential marketing. Standard 15-second loop placements on the TSX screen are sold through media buying agencies, and public price cards are not typically published. Industry estimates from DOOH publications place standard TSX screen placements in the $15,000–$60,000 per four-week range for a 15-second spot running at a typical ad frequency.
For context: at 50 million annual visitors, a four-week Times Square campaign reaches an estimated 3–5 million unique passersby. The cost-per-thousand (CPM) for premium Times Square placements is higher than most digital channels, but the earned media value — through photographs, social shares, and news coverage — often exceeds the direct impression value for brand campaigns designed for publicity.
15 seconds of fame at Times Square is also offered through consumer-facing products. Several services allow individuals to purchase a brief personal message or photo display on Times Square screens — typically as a birthday or anniversary surprise — for prices ranging from a few hundred to a few thousand dollars, depending on screen size, time of day, and display duration.
How to time Google Slides for 15 seconds per slide: In Google Slides, open the Publish to web dialog (File → Share → Publish to web), select Link, and set the auto-advance dropdown to "Every 15 seconds." This plays your presentation automatically with each slide advancing on a 15-second interval — useful for looping lobby displays, event signage, and self-running kiosk presentations. The published link runs in any browser without presenter control.
The Jeopardy 15-second timer is a common classroom and trivia adaptation. In the television programme, Final Jeopardy uses a 30-second think period with the famous Jeopardy theme playing. However, in teacher-designed classroom Jeopardy and pub quiz adaptations, a 15-second timer per question is frequently used as a fair response window — enough time to recall an answer without extended deliberation. A 15-second countdown timer displayed on a projector screen creates the same tension-building effect as the TV version.
BIOS boot timer 15 seconds: Many PC motherboard BIOS and UEFI firmware settings include a countdown timer at startup — commonly set to 5 or 10 seconds — that gives users a window to press a key and enter settings before the system boots to the operating system. A 15-second BIOS countdown appears on some older or custom-configured systems. This is typically changed in the BIOS/UEFI settings under Boot → Boot Wait Time or similar menu.
The New York Times 15-second video contest has been a recurring feature where readers submit short video clips of exactly 15 seconds responding to a theme or prompt. The format reflects the growing dominance of short-form video content and the creative constraint of the 15-second TikTok and Instagram Reel format, which popularised the duration as a standard unit of social video.
15-second eye lead time defined: In the context of driver training, a 15-second eye lead time means scanning the road 15 seconds of travel time ahead of your current position. At 30 mph this is approximately 660 feet; at 60 mph it is approximately 1,320 feet; at 70 mph approximately 1,540 feet. The Smith System codified this as the first principle of defensive driving: "Aim High in Steering" — looking well ahead rather than directly in front of the vehicle. This practice reduces the frequency and severity of emergency braking situations and is taught to commercial vehicle drivers and new motorists alike.
Click the Loop button on this page (or press L) before pressing Start. With Loop enabled, the timer restarts automatically each time it reaches 0:00 and a running lap count appears beside the Loop button. This is ideal for Tabata rest periods, timed exercise sets, and classroom quiz rounds where you need a consistent repeating interval.
At a normal resting heart rate of 60–100 BPM, you should count 15 to 25 heartbeats in 15 seconds. Multiply your count by 4 to convert to beats per minute. A count of 18 beats = 72 BPM (normal). A count of 25 beats = 100 BPM (upper normal limit). Athletes may count only 10–15 beats (40–60 BPM), which is normal for trained individuals. Take your pulse at the wrist (radial) or neck (carotid) for best accuracy.
A standard 15-second digital ad slot on a Times Square billboard typically ranges from $5,000 to $50,000+ for a four-week campaign, depending on screen prominence, time of day, and season. Premium screens like TSX Entertainment's 1515 Broadway display can run significantly higher. Prices are not publicly listed and are quoted by media agencies. Holiday season rates are substantially higher than off-peak periods.
The number of cricket chirps in 15 seconds varies with temperature according to Dolbear's Law (1897): count chirps in 15 seconds and add 37 to estimate degrees Fahrenheit. At 70°F, expect approximately 33 chirps in 15 seconds. At 60°F, approximately 23 chirps. At 80°F, approximately 43 chirps. Chirp rate increases proportionally with ambient temperature.
A 15-second eye lead time is the distance ahead a driver should be visually scanning to ensure adequate reaction time. It is a core principle of the Smith System of defensive driving. At 60 mph, 15 seconds of travel = approximately 1,320 feet (0.25 miles). At 70 mph, approximately 1,540 feet. Scanning this far ahead allows drivers to identify hazards — stopped vehicles, pedestrians, road debris — with enough time to react without emergency braking.
Normal prothrombin time (PT) is approximately 11 to 13.5 seconds. A PT result of 15 seconds is mildly prolonged, meaning the blood is taking slightly longer than normal to clot. This can indicate vitamin K deficiency, early liver disease, warfarin or other anticoagulant therapy, or clotting factor deficiency. A single PT of 15 seconds requires clinical interpretation — the significance depends heavily on the patient's medication history, INR value, and clinical context.
The playback duration of a 15-second time lapse depends on your recording interval and playback frame rate. At 1 frame per second → played at 30 fps: 15 frames ÷ 30 fps = 0.5 seconds of playback. At 1 frame per 5 seconds → played at 30 fps: 3 frames ÷ 30 fps = 0.1 seconds (barely one frame). For a useful 15-second time lapse clip at 30 fps, you would need to record for 7.5 minutes at 1 frame per second, producing 450 frames = 15 seconds of playback.
The 45/15 interval protocol is used in circuit training, strength-endurance workouts, and group fitness classes. The 3:1 work-to-rest ratio is demanding muscularly rather than primarily aerobic, making it well-suited for bodyweight exercises, kettlebell circuits, and resistance training where you want high training volume without a pure cardio stimulus. Common exercises: squats, push-ups, lunges, rows, and core work. Use the 45/15 Circuit preset on this page to run it automatically.
In Google Slides: go to File → Share → Publish to web. In the Link tab, find the auto-advance dropdown and select "Every 15 seconds". Click Publish and copy the link. When opened, the presentation advances automatically on a 15-second cycle, looping from the beginning. This is useful for lobby displays, event slideshows, and self-running kiosk presentations.
Click the 1:15 quick-set button on this page. The timer switches to 1 minute 15 seconds (75 seconds total) immediately. Alternatively, on Google Assistant say "Hey Google, set a timer for 1 minute and 15 seconds." On Siri: "Hey Siri, set a timer for 1 minute 15 seconds." The 2:15 and 5:15 buttons on this page work the same way for those durations.