What this tool produces
This tool takes timestamped events, sorts them into order, and calculates the interval between each one and the one before it.
It exists because gaps are what get questioned. A timeline that shows a 95 minute interval between two recorded actions invites the question of what happened during it, and it is far better to answer that from contemporaneous notes than from memory. This is a teaching and planning aid, not a casework tool.
Timeline events
Enter one event per line as ISO date/time | description.
Before you build a timeline
- Enter one event per line, as an ISO date and time, then a vertical bar, then a description.
- Use a consistent time source. Clocks on cameras, phones and body-worn devices drift, and a reconciled timeline needs the offsets known.
- Record events as they happen. A timeline assembled afterwards is a reconstruction and should be described as one.
- Gaps are informative. A timeline with none may mean nothing happened, or that nothing was recorded.
Devices at a scene rarely agree. A camera two minutes fast and a body-worn video three minutes slow produce a five minute discrepancy between two records of the same moment. Standard practice is to photograph a reference clock or record each device's offset against a known time source at the outset.
How this calculator works
Sort, then difference:
Parse each line into a timestamp and a description
Sort chronologically
Gap = current timestamp − previous timestamp, in minutesSorting means entries need not be typed in order, which is useful when reconciling several sources. Lines that cannot be parsed as a date are dropped rather than causing an error, so it is worth checking the row count against what you entered.
Worked example: three events
Using the default figures — scene secured at 09:00, photography started at 09:35, first item packaged at 11:10:
- Scene secured — first event, no gap
- Photography started — 35.0 minutes later
- First item packaged — 95.0 minutes later
The 95 minute gap is the one that would be asked about. It may be entirely accounted for by the photography itself — 135 images at a minute each would fill it — but that is only demonstrable if the intervening work was recorded. The value of the timeline is that it identifies which gap needs an answer before anyone else does.
Common mistakes
- Mixing time sources without reconciling offsets. Devices drift relative to each other.
- Reconstructing a timeline afterwards without saying so. Contemporaneous and reconstructed records differ in weight.
- Assuming an unparsed line was included. Check the row count.
- Recording only the notable events. Routine actions explain the gaps.
- Using local time without noting daylight saving transitions.
Frequently asked questions
Why do time records matter so much?
Because sequence and duration underpin a great deal of investigative reasoning, and because a documented timeline is what allows an account to be tested. Where a timeline is incomplete, the gaps become the focus of questioning, whether or not anything happened in them.
How are device clocks reconciled?
By recording each device's offset from a known reference at the start, and applying that offset when combining records. Photographing a reference clock or a phone showing network time is a common approach. Where offsets were not recorded, they can sometimes be recovered afterwards if the device has not been reset.
What format should timestamps use?
ISO 8601 — year, month, day, then T, then hours and minutes — is unambiguous internationally and sorts correctly as text. Formats like 07/18/2026 or 18/07/2026 are ambiguous between conventions and are a genuine source of error in records shared between organisations.
Should routine actions be recorded?
Yes. A note that photography ran from 09:35 to 11:05 explains a gap that would otherwise need explaining from memory months later. Contemporaneous notes covering routine work are what make a timeline defensible rather than merely plausible.
Is what I enter stored?
No. Everything you enter is processed in your browser and is never transmitted or retained. Even so, treat any public website as an unsecured environment and do not enter identifiable case information.
Related tools
References
- GOV.UK — Forensic Science Regulator codes of practice on records and continuity
- Information Commissioner's Office — record keeping and personal data in investigations
Sources are checked at publication and can change — how I choose and check references.