iStints is built for endurance race teams (iRacing and real-world motorsport) who want a clear stint timeline: lap targets, predicted pit windows, and a shared plan the whole team can follow.

iStint.com is an advanced split time calculator designed to help racers analyze and optimize their racing stint strategies for peak performance on the track.

It turns a few key inputs (race duration, average lap time, fuel capacity, fuel per lap) into a consistent plan: estimated total laps, stint length, pit strategy, and a timeline you can share with teammates.

• Driver management: add/remove drivers and edit names.
• Race configuration: duration, average lap time, fuel capacity, fuel per lap.
• Stint timeline: builds a predictable sequence of stints and pit windows from your inputs.
• Pit stop adjustments (draft-first): changes stay local until you apply / save.
• Shareable plan: Sync generates a link your team can open.
• Calendar export: add stints/events to your calendar for coordination.
• Sticky action bar: quick access to Apply/Sync buttons when scrolling long timelines.
• Toast notifications: instant feedback when you save pit adjustments or sync plans.

Garage61 integration helps you turn real telemetry/race data into planning inputs and team insights. It can import driver data (when available) and compute metrics like pace percentiles, consistency, and pit-related estimates.

It is optional. If you do not use Garage61, you can still plan stints by entering your average lap time and fuel values manually.

p50 means the 50th percentile (the median). For lap time, half the laps are faster than p50 and half are slower. p50 is usually more stable than an average because it is less affected by extreme outliers.

IQR is the interquartile range (p75 − p25). Smaller IQR means more consistent laps. Use it to compare how “repeatable” a driver’s pace is when planning long stints and handoffs.

Pit in lap is the lap where the car enters pit lane. Pit out lap is the lap immediately after leaving the pits. These laps are usually much slower than normal pace due to pit entry/exit speed limits and the pit lane itself.

When Garage61 data is available, iStints can estimate p50 pit-in and pit-out lap times. These are useful for estimating pit loss and building more realistic pit windows.

Pit loss vs pace is a baseline estimate of how much time a pit cycle costs compared to normal laps, using percentiles: (pitIn(p50) − pace(p50)) + (pitOut(p50) − pace(p50)).

This is a “track loss” estimate, not a full service-time model. Your real pit stop may be longer if you add fuel, change tyres, or have repairs.

Garage61 stats depend on the selected dataset (car, track, time period, and other filters). Changing filters changes which laps/stops are included, so percentiles and pit estimates can move noticeably.

Tip: if you are comparing drivers, keep filters consistent so you are comparing the same conditions.

Yes. When you Sync, iStints can generate a short share URL in the /s/<id> format. This is the easiest link to copy into Discord or team chats.

If a link stops working, the plan may have expired or been deleted—Sync again to publish a new copy and share the new link.

• Verify you selected the correct car + track. Many stats are scoped to those filters.
• If the dataset is small, percentiles can jump around. Try a longer time period or broader session types.
• Pit stats require pit/refuel events. If you have no pit stops in the selected dataset, pit-in/out values may show as N/A.
• If values look implausible, double-check your filters and compare with a known lap time from the same conditions (weather/track state/traffic).

A Driver Card is the compact summary tile in the Garage61 drivers grid. It shows the driver name plus a small stats summary (pace p50, consistency IQR, fuel p50, and pit-related p50 when available).

You can click the driver name to open the Driver Modal (full details). Some cards also show actions like “Add to stint plan” / “Remove from stint plan” when the Split Calculator is editable.

Driver Cards also control Team Average: use the +/- action to include or exclude a driver from the Team Average calculation.

The Driver Modal is the detailed view for a single driver. It includes deeper stats, per-event breakdowns, and (when present) refuel/pit stop evidence used to compute pit-in/out and pit loss estimates.

• Header: confirms the currently selected Track and Car (important, because all stats are scoped to the current filters).
• Stats summary: pace percentiles, consistency (IQR), fuel percentiles, and pit metrics when enough pit evidence exists.
• Session buttons (Practice / Qualifying / Race): switches the driver’s details to that session type when the driver has multiple events available.
• Overview Pit with Refuels (when available): shows refuel stop counts, total fuel added, and a list of stops; each stop expands into a detailed breakdown (fuel added, time stopped, in/out laps, and pit-loss estimates).
• Lap details: some rows allow opening a “Lap details” view to inspect the raw lap flags/metrics behind the summary.

Use the Driver Modal when you want to validate where the numbers come from (laps, events, pit stops) instead of relying only on the compact Driver Card.

Team Average is computed from the drivers you include in the Garage61 drivers grid. It is meant to represent your team’s planning baseline for the currently selected car/track/period.

Use the +/- action on each Driver Card to include/exclude that driver. There are also quick actions to add all drivers to Team Average or remove all drivers from Team Average.

• Pace: p50/p75/p90 and best lap (min), plus consistency (IQR) and offsets from p50 (safe and conservative).
• Fuel: fuel used per lap percentiles (p50 and p75) based on filtered “normal” laps.
• Pit stops: pit-in/out and pit-loss estimates when pit/refuel evidence exists. This tab may also show a fueling-rate estimate and an “expected pit loss” helper based on the stops observed in the dataset.
• Dataset: transparency counts (drivers included, laps used, sessions used, setup type) and quality notes such as invalid pit stops for pit-loss computation.

If you see a message like “Outlier trimming removed X slow lap(s)”, it means the “Trim slow outliers” filter removed laps slower than median + 3×IQR (after smart filtering).

The Team Average card can always show stats, but “Apply” only works when the Split Calculator plan is editable AND there is at least 1 driver in the stint plan.

If you see “Apply Button is disabled, while no drivers are added to the stint plan.”, add a driver in the Driver List first (then create/apply the stint plan if needed).

These fields are metadata for your plan. They help your team recognize the plan in shared links and exported calendars.

• Team name + Event name: shown in shared plan titles and exports.
• Track name + Car name: optional context for the same plan.

If you leave them blank, the stint plan can still work; the shared plan will just have less context.

The Driver List is the source of truth for who is on the stint plan. Each driver row shows a status (Valid / Needs at least X laps) and, after a timeline exists, the driving-time estimate and the list of assigned stints.

Use the Driver List input at the top: type a name and press Enter or click “Add Driver”. You need at least 1 driver to create the stint plan.

If “Add Driver” is disabled, check that the plan is editable and that your race duration is set (some flows keep the add action disabled until race length is known).

The current limit is 8 drivers. If you hit the limit, remove a driver before adding another.

In the Driver List, each driver row has a delete (trash) action. Remove the driver you no longer want on the plan.

You cannot remove the last remaining driver (at least 1 is required). Add another driver first, then remove.

Use the edit (pencil) action on a driver row, change the name, then save. Keeping names consistent helps Garage61 matching and keeps the stint plan readable for teammates.

iStints uses a draft → commit workflow. When you edit race inputs (fuel, lap time, team/event fields) or drivers, those edits are draft changes until you apply them to rebuild the stint timeline.

• First plan: the button shows “Create your first stint (free)” and stays disabled until you have at least 1 driver.
• After a plan exists: the button shows “Apply changes” (or “Update Stint” in some parts of the UI) and becomes enabled when there are pending edits to apply.
• Sync is separate: it publishes the applied plan to a share link. If you edit again, you must Apply/Update first, then Sync to publish the new snapshot.

Pit stop loss plan is your baseline estimate for how long the car is stationary in the pits. The planner uses it as the default pit delay unless you override pit loss per stint in Pit Stop Adjustments.

Garage61 “pit loss vs pace” is a different kind of number: it estimates track loss from the pit-in and pit-out laps compared to typical pace. Depending on series and strategy, stationary time and track loss can be very different—use the one that matches what you are planning.

Use the Team dropdown at the top of the Garage61 page. Selecting a specific team scopes imports/filters to that team when possible.

If you leave team blank ("All my teams"), iStints will try to use all teams that are available to your connected Garage61 account (and any server-configured team slugs). If you have no teams or no activity for the selected period, you may see empty results.

When Split Calculator team name is empty, selecting a Garage61 team can auto-fill it (best-effort) so your shared plan has a readable team name.

Choose Car first, then Track. Track selection is disabled until a car is selected. Period is disabled until a track is selected.

After selecting car/track/period, click “Import selected car/track” to fetch laps for those filters. If you change filters later, stats may change because the dataset changed.

If Split Calculator track/car fields are empty, selecting a Garage61 car/track can auto-fill them (best-effort) to keep the plan metadata consistent.

Recommended order:

1. Add drivers first. You must add at least 1 driver to create the stint plan.
2. Set team + event names (helps with sharing and calendar export).
3. Fill race config: event duration, average lap time (mm:ss), fuel capacity, and fuel per lap.
4. Create/Update the stint to rebuild the timeline after edits.
5. Sync to save and generate a shareable link for your team.

Use the driver list to add names one by one. If you have 0 drivers, the app won’t create stints—add at least one driver to enable the stint plan.

Fill Team name and Event name in the main form. These are used in share links and calendar export titles.

After changing race config or drivers, click Create Team Stint (first time) or Apply changes / Update Stint (when available) to rebuild the timeline.

Yes. Fuel capacity and fuel-per-lap accept decimals (e.g., 3.4). The inputs also allow intermediate typing like 3. while you’re editing.

Minutes and seconds fields are optimized for quick edits: clicking the field selects the whole value so you can type over it, and the display is padded (e.g., 00, 08).

Use Sync to save your plan and generate a share link. Anyone with the link can view the plan.

Sync saves your current plan as a baseline and publishes the current version for sharing. Recommended flow:

1. Make your edits (drivers, lap time, fuel, pit adjustments).
2. Click Create/Update Stint if the timeline needs rebuilding.
3. Click Sync to persist and share the updated plan.

Tip: if you’re testing scenarios, you can avoid Sync until you’re confident.

When you Sync, the app uploads your plan so it can be loaded via a share link. This typically includes: team/event names, race configuration, drivers, the stint timeline, and per-stint pit adjustment details.

There is no login required. Anyone who has the share link can access the shared plan, so treat the link like a secret and only share it with your team.

Shared links are meant for viewing and coordinating. The safest workflow is: one person owns the “edit + Sync”, and everyone else consumes the shared link.

Yes. Use Share URL to copy a link to your clipboard and send it to your team. You can also manually copy the visible values (lap time, fuel, pit details) if you’re moving them into another tool.

Some shared-plan flows provide an Access PIN and an Edit PIN. Access PIN is used to open protected shared plans; Edit PIN is used for protected edit workflows.

Save these PINs when they are shown. They may not be recoverable later, so store them in a safe place before closing the modal.

iStints supports multiple languages. Use the Language selector to switch the UI.

Restore brings back the last synced baseline saved in your browser, so you can quickly undo local edits.

When you scroll through long stint timelines, a fixed action bar appears at the bottom of the screen, giving you quick access to "Apply Changes" and "Sync" buttons without scrolling back to the top.

The bar automatically shows when the main action buttons scroll out of view and you're near the end of the timeline. It respects the same edit permissions as the main buttons.

Toast notifications appear in the top-right corner to give you instant feedback when you save pit adjustments, sync plans, or make other important changes. They automatically disappear after a few seconds.

The app avoids spamming duplicate notifications—if you edit multiple fuel fields quickly, you'll only see one notification per field type when you finish editing.

Day phases are a simple visual hint of the time of day for a stint (based on the stint timestamp and your device time zone). They help teams quickly spot night-time stints and handoff windows.

• Dawn: 04:00–06:00
• Sunrise: 06:00–07:00
• Morning: 07:00–12:00
• Afternoon: 12:00–17:00
• Sunset: 17:00–19:00
• Dusk: 19:00–21:00
• Night: 21:00–02:00
• Late night: 02:00–04:00

If the phase looks “wrong”, double-check your event start date/time and your device time zone, then rebuild the stint timeline.

Timeline clock times are computed from your event start time and a time zone setting.

If times look wrong, double-check your device time zone, then use Calibrate time zone or a custom GMT offset.

• Default: uses your computer time zone.
• Custom: set a GMT offset (e.g., +2 or -3.5) if needed.
• Per-driver: you can assign a driver time zone and toggle local time to see slots in the driver’s local time.

The local-time toggle lets you view/edit race start times in local time while iStints keeps internal values normalized in GMT/UTC.

Use it when coordinating across regions. If results look off, verify your device time zone and then rebuild/apply the plan.

Support is optional. If iStints is useful to you, donations help cover hosting and maintenance.

The “Support & Donate” link opens Buy Me a Coffee (a third-party service). Donations and payments are processed by them, and iStints does not collect or store payment details.

Pit Stop Adjustments is a per-stint panel to record what you plan to do (and what actually happened): planned pit yes/no, pit stop triggers, stint result notes, track condition, tyre changes, fuel, and pit-loss estimates.

Important: it is draft-first. Changing an input does not immediately rebuild the stint timeline. Your edits become “real” only when you click Save (for a field) or Save all changes.

Pit Lap (box lap) is special: saving it can trigger a downstream recalculation of the timeline because it changes where the pit happens. After changing it, expect later stints to shift.

All pit adjustments now properly activate the "Apply Changes" button at the top of the page, so you know when unsaved changes exist.

These fields help you record refueling details for a stint. They do not automatically change the race config fuel numbers; they are per-stint adjustments/notes that you can Sync and share with the team.

• Full tank: mark this if you filled the tank to capacity (uses your configured tank capacity as the cap).
• Fuel left (liters): how much fuel was left when you pitted / ended the stint.
• Fuel added (liters): how much fuel you added at the stop (clamped to a sane range based on the tank).

If you’re scenario-testing, remember to Save / Save all changes so your teammates see the same pit notes in the shared link.

Pit Loss helps estimate how many seconds you lost compared to a normal lap. You can enter one (or both) of the two lap-time fields in seconds:

• Pit lap time (seconds): the lap where you entered pit lane.
• Lap after pit time (seconds): the out-lap after leaving the pits.

You can also record repairs and stop components (car damaged, required fix, optional fix, pit stop time, fast lane time). The estimate avoids double-counting: if you provide both lap times, the extra repair/stop components are treated as already included in those laps.

Use Save / Save all changes to persist the pit-loss info into the shared plan. If the estimate looks unreasonable, verify your average lap time and that you entered pit lap and out-lap times in seconds (not mm:ss).

Yes. The app stores your stint plan in your browser’s local storage (localStorage) to preserve it on this device. You can remove it anytime by clearing this site’s data in your browser settings.

When you Sync, the app also stores a baseline snapshot locally. This lets you use the Restore feature to undo local edits and return to the last synced state.

iStints uses a two-phase editing workflow: draft changes stay in your browser until you explicitly commit them.

1. Draft: You edit pit adjustments, fuel, driver assignments, etc. These changes are held locally in your browser state.
2. Commit (Apply/Save): Click "Apply Changes" or individual field "Save" buttons to commit your drafts and trigger timeline recalculation if needed.
3. Persist (Sync): Click "Sync" to upload the committed state to the server and generate a shareable link.

This workflow lets you experiment with scenarios safely—your changes don't affect the shared plan until you Sync.

Shared plans may be automatically deleted after a retention period to save server space. The exact retention may change over time; if you want to keep a plan available, Sync again to publish an updated copy.

If a teammate opens a link and it no longer loads, the plan was likely deleted/expired. The owner should Sync again and share the new link.

• Timeline didn’t change after editing: click Create/Update Stint (the timeline only rebuilds when you apply/update).
• Pit adjustments “did nothing”: Pit Stop Adjustments is draft-first—click Save or Save all changes to persist them.
• Shared link shows old values: the link is a snapshot at the last Sync—Sync again and re-share.
• No stints are created: you must add at least 1 driver before creating the stint plan.
• Availability add is blocked: save current availability edits first, then add a new slot.
• On mobile, main content is hidden when there are no drivers. Add your first driver to show the content panel.

Yes. iStints is free to use today. If premium features ever exist in the future, the core planning workflow will remain accessible.

Yes. The UI is designed to work on desktop and mobile, so you can quickly check the timeline and pit windows while on the go.

This is a planning tool. Real races include traffic, incidents, weather, cautions, fuel saving, and driver pace differences. Always validate numbers with your team and adjust the plan during the race.

You are free to use iStints to plan your races and share your plans using the built-in sharing features. The application, its code, and its written content are protected intellectual property—avoid copying, redistributing, or commercial reuse outside the allowed sharing workflows unless you have explicit permission from the creator.

If you want to collaborate, contribute, or reuse parts of the project, reach out to the author to discuss permissions and attribution.