Lab timer settings

Sound cues apply to the repeatable countdown. Stopwatch laps stay silent.

SoundFinal beeps

Space stopwatch / L lap / C countdown / R reset / T repeat / F fullscreen

Stopwatch + Laps

mm:ss.cc

0:00.00

Ready

Max laps

Laps (newest first)

Start the stopwatch, then press L to record laps (splits).

Repeatable Countdown

step timer

Common step times

Countdown setup

Custom step (seconds)

Repeat step

If Repeat is on, the countdown restarts automatically after it hits zero.

1:00

Step Countdown - Repeat on - Ready

C start/pause - R reset - T toggle repeat - F fullscreen

Lab Timer (Experiments + Reaction Time)

Use a stopwatch with laps and a repeatable countdown for timed lab steps, optional sound, and fullscreen step timing.

How it works

Lab Timer is a practical timing page for experiments and repeatable procedures. It combines two tools that cover most bench timing needs: a stopwatch with lap splits (for reaction timing, event markers, and repeated trials) and a repeatable step countdown (for timed protocol steps you want to run consistently).

This page is not a lab methods guide and it does not ask you to type in long plans. It is built to help you run timing cleanly: start and pause instantly, capture lap splits without thinking, loop a step timer when you are repeating the same action, and switch to a big fullscreen display when your hands are busy or the screen is across the room.

Everything runs locally in your browser, no account required. If you need a dedicated single-purpose tool, the links at the bottom point you to a simple Stopwatch, a one-shot Countdown Timer, or Multiple Timers for parallel steps.

Stopwatch + lapsStep countdownRepeat stepSound cuesFullscreenShortcuts

Quick use (what most people do)

1) Decide which tool fits the moment: Stopwatch for reaction timing and trials, or Step countdown for timed protocol steps.
2) Stopwatch: press Space to start/pause, then press L to capture a lap split (time since your last lap) plus the running total.
3) Countdown: pick a common step time (10s, 30s, 60s, 2m, 5m, etc.) or enter seconds, then start it with C (or Start). Turn Repeat step on if you want it to loop automatically.
4) If your screen needs to be readable at a distance, press F to fullscreen the step timer. Exit with Esc.
5) Between runs, press R to reset both timers quickly.

What you are recording (so laps mean something)

A lap on this page is a split plus a total. Split is the time since your previous lap. Total is the overall stopwatch time. That pairing lets you capture event-to-event timing while still keeping the context of how far into the run you were when it happened.

Practical checklist

If you want audible cues, enable Sound. Some browsers require you to press Start once before audio plays.
If you want a warning before zero, enable Final beeps to hear beeps during the last 5 seconds.
If shortcuts do nothing, click the Lab Timer card once so it has focus.
If you need a hands-busy control, fullscreen lets you tap/click the timer area to start or pause the countdown.
If you need different step lengths back-to-back, a single repeat step timer is the wrong tool. Use Multiple Timers.

Shortcuts: Space stopwatch start/pause, L lap, C countdown start/pause, T repeat toggle, R reset, F fullscreen, Esc exit.

What the page actually offers

Stopwatch + Laps is your “mark events” tool. It shows time in mm:ss.cc (minutes, seconds, centiseconds). That makes short reaction intervals easy to read without staring at milliseconds. Pressing Lap stores a split and a total so you can see both the gap between events and where the event occurred in the overall run. The list is shown newest-first so you always see the most recent entries at the top.

Repeatable Countdown is your “step timer” tool. It is intentionally simple: you set a single duration in seconds, then run it once or loop it. If Repeat step is on, the countdown restarts automatically at zero using your current step duration. If Repeat is off, it stops at zero. This is designed for procedures where you want the same timing repeated reliably, without re-clicking a preset each time.

Fullscreen applies to the step countdown box only. That is deliberate: the countdown is what people usually put on a bench display or shared screen. Fullscreen adds a compact top bar (Start/Pause, Reset, Repeat On/Off), and the timer area becomes clickable so you can start/pause without hunting for small controls.

Sound is optional. With Sound enabled, you will hear cues for actions and completion. With Final beeps enabled, you will hear one short beep per second in the last 5 seconds before the countdown reaches zero. This is built for hands-busy workflows where you want a clear “get ready” signal before the step ends.

Scenarios with real numbers (what you will see on this page)

These scenarios use values you can enter directly in the Lab Timer. The lap output format and countdown display match what you will see on-screen.

Scenario 1: Reaction timing with lap splits

You want event-to-event timing plus a running total.

Stopwatch: - Press Space to start - Press L at each event Example laps you might see (mm:ss.cc): Lap 1 split: 0:01.24 total: 0:01.24 Lap 2 split: 0:01.08 total: 0:02.32 Lap 3 split: 0:00.96 total: 0:03.28 Lap 4 split: 0:01.12 total: 0:04.40 What this tells you: - Your event gaps were ~1.24s, 1.08s, 0.96s, 1.12s - You were 4.40s into the run at the 4th event

Scenario 2: Repeating a 60-second step (looping countdown)

Common for repeated steps with the same duration.

Countdown: - Step: 60 seconds - Repeat step: ON - Sound: ON (optional) What you will see: - 1:00 → 0:59 → ... → 0:05 → 0:04 → 0:03 → 0:02 → 0:01 → 0:00 - Immediately restarts to 1:00 when Repeat is ON If Final beeps is ON: - A beep at 0:05, 0:04, 0:03, 0:02, 0:01 - Completion cue at 0:00

Scenario 3: Short step with a warning (15 seconds + final beeps)

You need a heads-up right before a step ends.

Countdown: - Step: 15 seconds - Repeat step: OFF - Sound: ON - Final beeps: ON What you experience: - Quiet countdown until the last 5 seconds - Beeps at 0:05, 0:04, 0:03, 0:02, 0:01 - Completion cue at 0:00 and the timer stops

Scenario 4: Long step on a wall display (5 minutes fullscreen)

Readable from across the room with minimal controls.

Countdown: - Step: 300 seconds (5:00) - Press F for fullscreen On-screen behavior: - Large 5:00 display that auto-fits the screen - Top bar with Start/Pause, Reset, Repeat On/Off - Tap/click the timer area to start/pause - Press Esc to exit fullscreen

Scenario 5: Repeated trials with quick resets

You want consistent start conditions between runs.

Workflow: - Stopwatch trial: Space start → L marks event(s) → Space pause - Press R to reset stopwatch and countdown Example: 12 trials with clean starts - Each trial begins at 0:00.00 - Laps list stays within your Max laps cap

Scenario 6: When you should switch tools

The Lab Timer is built for a single step countdown, not multi-step sequences.

If you need step durations like: - 30s, then 2m, then 10m, then 45s Use instead: - Multiple Timers (one timer per step) or a dedicated Countdown Timer If you only need one repeating duration: - Stay on Lab Timer and enable Repeat step

Why this page is useful in practice

A lot of timing pages force you into one model: either a pure stopwatch or a pure countdown. Lab work often needs both. You may be capturing reaction timing in short bursts, then immediately switching to a repeatable step timer for consistent pacing. This page keeps that switch frictionless, with clear display, optional audio cues, and a reset that clears both tools at once.

If your workflow is simpler, use the specialized pages: Stopwatch for a dedicated lap view, Countdown Timer for a simple one-shot countdown, or Multiple Timers for parallel or staggered steps.

Related tools (same site, different job)

Use the closest match to what you are actually trying to time.

Shortcuts: Space L C T R F Esc

Stopwatch →Countdown Timer →Fullscreen Timer →Multiple Timers →Time Calculator →Reaction Time Test →Milliseconds Converter →

Technical details (timing, sound, focus, fullscreen)

Optional notes if you rely on exact behavior

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Stopwatch update loop

The stopwatch updates using animation frames and a monotonic timing source (performance timing) so the displayed time stays consistent across pauses. Visual updates can look less smooth on a slow device, but elapsed time is still computed from a stable clock.

Countdown timing

The countdown targets its end time using a monotonic clock instead of relying only on setInterval. This reduces drift when the browser is busy. The display rounds to whole seconds for readability, while the internal target remains time-based.

Audio behavior

Web audio may be blocked until a user gesture occurs. If cues are silent, click/tap a Start button once, then try again. Final beeps fire once per second in the last 5 seconds only when Sound is enabled.

Keyboard focus rules

Shortcuts are handled on the Lab Timer card. If they do not work, click the card once to focus it. While typing in a number input, shortcuts are ignored to prevent accidental starts.

Fullscreen targeting

Fullscreen is applied to the countdown box so the time display stays large and readable. The fullscreen top bar exposes Start/Pause, Reset, and Repeat On/Off, and the timer area is clickable for start/pause.

Need parallel steps? Use Multiple Timers when you need more than one independent timer.

Want a minimal big display? Use Fullscreen Timer for a simple fullscreen countdown view.

In one sentence: this lab timer combines a lap-based stopwatch for reaction timing and trials with a repeatable step countdown you can run fullscreen, with optional sound cues, final beeps, and keyboard shortcuts for quick control.

Keyboard shortcuts

Click the Lab Timer card once, then use the shortcuts below. Shortcuts won’t trigger while you’re typing in an input, select, textarea, or editable field.

Key	Action
`Space`	Stopwatch start / pause
`L`	Record lap (stopwatch)
`C`	Countdown start / pause
`T`	Toggle Repeat step (countdown)
`R`	Reset stopwatch + countdown
`F`	Toggle fullscreen (countdown box)
`Esc`	Exit fullscreen

Tip: if shortcuts do nothing, the card probably isn’t focused. Click once on the Lab Timer card, then try again.

Common scenarios

Use this page for lab-style timing: a stopwatch with lap splits for observations and trials, plus a repeatable step countdown you can run fullscreen. Enable sound cues if you want hands-busy alerts.

Reaction timing with a lap-based stopwatch

Start the stopwatch and press L at each event to capture split times (time since the previous lap) plus the running total. Use Reset between trials to get a clean run.

For

Anyone measuring reaction timing, repeated trials, or event-to-event intervals where splits matter.

Not for

You want a dedicated reaction-speed test with built-in scoring. Use Reaction Time Test.

Reaction Time Test →Stopwatch →

Repeat the same timed step in a protocol (looping countdown)

Set a step duration in seconds, turn Repeat step on, then Start. The countdown will restart automatically at zero, ideal for repeated mix/wait/invert/check cycles.

For

Step-based protocols where the same timed action repeats many times and you want an automatic loop.

Not for

You need different step lengths in sequence. Use Multiple Timers for separate timers per step.

Multiple Timers →Countdown Timer →

One-off timed steps (single countdown, no repeat)

Pick a common step time (like 30s, 60s, 90s) or enter a custom value, keep Repeat off, then Start. Reset returns the countdown to your step duration for the next run.

For

Single timed steps such as short waits, spins, checks, or transfers where you don’t want looping.

Not for

You primarily need lap splits and totals. Use the stopwatch section on this page.

Countdown Timer →Stopwatch →

Big-screen bench display (fullscreen step timer)

Toggle fullscreen for the countdown box to maximize readability across the room. In fullscreen you can tap/click the timer area to start or pause, and keep controls in the top bar.

For

Benchtop, wall display, or shared screen use where the timer needs to be readable at a distance.

Not for

You want fullscreen for a general countdown page with fewer lab-specific controls. Use Fullscreen Timer.

Fullscreen Timer →Countdown Timer →

Audible step transitions (final beeps + completion cue)

Turn Sound on, then enable Final beeps to get a short beep each second during the last 5 seconds before zero, plus a completion cue at zero. Useful when you’re hands-busy and can’t stare at the screen.

For

Hands-busy steps where you need an audible heads-up before the step ends.

Not for

You need a fully silent setup. Use Silent Timer.

Silent Timer →Countdown Timer →

Parallel steps or staggered timers

If you’re running multiple things at once (staggered incubations, overlapping checks), switch to Multiple Timers so each step has its own independent timer and controls.

For

Any workflow where a single repeating step timer is not enough and you need concurrent timers.

Not for

You only need one step time repeated or a single stopwatch run. Stay on this page.

Multiple Timers →Lab Timer →

Tip: Press Space to start/pause the stopwatch, L for laps, C to start/pause the countdown, T to toggle repeat, R to reset both, F for fullscreen, and Esc to exit. If shortcuts do nothing, click the Lab Timer card once to focus it.

Frequently Asked Questions

What does this Lab Timer do?

It gives you two lab-focused timing tools on one page: (1) a stopwatch with laps for observations and repeated trials, and (2) a repeatable step countdown for timed protocol steps. You can go fullscreen for a large display, enable optional sound cues, and use keyboard shortcuts for quick control.

How do stopwatch laps work here?

Each Lap records two values: the split time since your previous lap, and the total elapsed time at the moment you pressed Lap. Laps are listed newest-first, and the fastest split is labeled as the best lap.

What does the Max laps setting do?

Max laps caps how many lap entries are stored and shown. This keeps the list manageable during long runs. If you lower Max laps below your current lap count, existing laps remain until you reset, but new laps won’t be added once the cap is reached.

What is the repeatable countdown for?

It’s for step-based protocols where you repeat the same timed step multiple times (for example: mix, wait, invert, vortex, check, transfer). Set a step duration in seconds, then turn Repeat on to automatically restart at zero.

What happens when Repeat step is on?

When the countdown reaches zero, it plays the completion cue (if Sound is on) and immediately restarts a fresh countdown using your current step duration.

What does Final beeps do?

If Sound is enabled and Final beeps is turned on, the countdown plays a short beep once per second during the last 5 seconds before it reaches zero. It’s meant to help you anticipate step transitions without staring at the screen.

Does fullscreen change how controls work?

Fullscreen applies to the step countdown box only. It shows a top bar with Start/Pause, Reset, and Repeat On/Off. You can also tap/click the timer area to start or pause. Exit fullscreen with Esc.

What keyboard shortcuts are supported?

Space toggles the stopwatch start/pause, L records a lap (stopwatch only), C toggles the countdown start/pause, T toggles Repeat for the countdown, F toggles fullscreen for the countdown, and R resets both timers. Shortcuts are ignored while you are typing in an input.

Why might I not hear sound cues?

Some browsers block audio until you interact with the page. If cues are silent, click/tap a Start button once, then try again. Also verify your device isn’t muted and volume is up.

Is this lab-grade or instrument-grade timing?

No. It is a browser timer for classroom labs, practice experiments, observations, and repeated steps. Browser timing, device sleep, tab throttling, audio permissions, and device performance can affect timing or perceived precision.

Which related timer should I use instead?

Need a simple single countdown? Countdown Timer. Prefer a dedicated stopwatch page? Stopwatch. Want a big, clean display with fewer controls? Fullscreen Timer. Running multiple steps in parallel? Multiple Timers. Specifically testing reaction speed? Reaction Time Test.

Lab Timer at a glance

Stopwatch with laps • Reaction timing splits • Step countdown (repeatable) • Fullscreen step view • Sound + final beeps • Keyboard shortcuts

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Use this page to time experiments in two ways: a stopwatch with lap splits, and a repeatable step countdown for protocols. Keep it visible on a bench display, run the step timer fullscreen, and control it quickly with keyboard shortcuts.

Stopwatch + lap splits. Start/pause with Space, then press L to record laps. Each lap stores a split (time since last lap) and a running total, useful for reaction timing or repeated trials.

Repeatable step countdown. Pick a common step time, or enter a custom duration in seconds. Turn on Repeat step to loop the countdown automatically for multi-step protocols.

Fullscreen step view. Use fullscreen for a clean, large countdown. While fullscreen is active, you can tap/click the timer to start or pause, and exit with Esc.

Sound cues (optional). Enable Sound for key actions and timer completion. If you enable Final beeps, the countdown will beep in the last 5 seconds before zero.

Fast reset behavior. Press R to reset both the stopwatch and the countdown to a clean start, useful between trials.

Readable on any screen. The time display auto-sizes to fit, so it stays clear on phones, laptops, and wall displays.

Quick use

1) Pick a mode: use the stopwatch for reaction timing (laps), or the countdown for step-based protocols.
2) Set your step: choose a common step time or enter seconds, then decide if Repeat should loop.
3) Run and record: Space starts the stopwatch, L records laps, C starts the countdown, and R resets.

Common lab timing patterns

Reaction trials: run the stopwatch and hit L at each event to capture split times.
Fixed step protocols: set a step duration (for example 30s, 60s, 90s) and turn Repeat on to loop hands-free.
Incubation/check cycles: use the countdown without repeat for a one-off step, then reset quickly for the next run.
Bench display: go fullscreen on the countdown for a big, easy-to-read timer across the room.

Related tools

Need a simple single countdown? Countdown Timer.

Prefer a dedicated stopwatch view? Stopwatch.

Want a focused, big-screen timer with fewer controls? Fullscreen Timer.

Running multiple steps in parallel? Multiple Timers.

Specifically testing reaction speed? Reaction Time Test.

Controls + behavior details▼

Keyboard shortcuts

Space stopwatch start/pause · L lap · C countdown start/pause · T toggle repeat · F fullscreen step view · R reset all · Esc exit fullscreen.

Shortcuts are ignored while typing in inputs.

Countdown display + repeat

The countdown displays seconds in a simple clock format and can loop automatically when Repeat step is enabled.

When Repeat is off, the countdown stops at zero.

Stopwatch laps

Laps record a split (time since your previous lap) and the total time at the moment you pressed Lap.

You can cap the list using Max laps to keep the panel lightweight.

Sound notes

Some browsers require a user gesture before audio will play. If you do not hear cues, click Start once, then enable Sound and try again.

Final beeps trigger once per second in the last 5 seconds before the countdown reaches zero.

Fast workflow. Use Space + L for reaction trials, then switch to the step timer with C. Hit R between runs to clear both timers instantly.