Numbers in subtitles: decimals, units and dates

Confirm the value before choosing its style

To review numbers in subtitles, listen for the complete quantity: the value, unit, range and any qualification such as “about” or “at least.” Confirm that meaning first. Then apply the language and destination’s number style, and watch the exported track with the matching video. Matching digits alone cannot tell you whether a caption is correct.

W3C’s caption guidance explains why automatic text needs review: recognition errors can change the message. Numbers deserve a separate pass because a small mark or short word can carry much of the meaning. “2.5 metres” and “25 metres” differ by one dot but describe very different lengths.

Use recordings and subtitle files you own or are authorized to edit and distribute. This guide proposes a manual review method. Polyglot can help you create, translate and edit timed text locally on a Mac, but this workflow does not imply automatic quantity checking, unit conversion or approval of the speaker’s factual claims.

Choose a number style for the actual delivery

Write down the subtitle language, regional variety and receiving platform before standardizing numbers. DCMP’s educational caption guide and Netflix’s English (USA) guide both discuss when to spell out numbers and when to use numerals, with exceptions for particular contexts. These are scoped style guides, not universal rules built into SRT.

If your destination specifies a guide, follow its current requirements. Otherwise, agree on a consistent house style with the editor: small numbers, measurements, fractions, times and dates should each have a deliberate treatment. Do not combine exceptions from several guides and call the result a platform standard.

For example, DCMP recommends spelling out measurement units. A production following that convention might retain “2.5 metres” rather than shorten the unit to “m.” Another destination may require a different treatment. Neither choice excuses a changed value, and a shorter number is not automatically easier to understand at playback speed.

Separate quantities from labels and identifiers

Classify a suspicious number before editing it. Is it a measured amount, a date, a clock time, a range, or an identifier such as a room number, model name or software version? The same punctuation can have different roles. Version 2.5 is a label, not a decimal measurement to round or convert.

Unicode’s number-format guidance distinguishes the decimal symbol from digit-grouping symbols, and both can depend on locale. In a track whose approved convention uses a decimal comma, a quantity written as 2.5 in another track might be written as 2,5. That is a notation change only if it still represents two and a half. Do not apply that replacement to every dot in the file.

Check the spoken words and an authorized reference when the notation is ambiguous. A product code with a leading zero should not lose it merely because a spreadsheet treats the entry as a number. A displayed “1,250” needs its context and source convention before you decide what amount it represents. Record the interpretation in words in your review notes so the reviewer is not comparing two equally ambiguous strings.

Keep the unit, boundary and uncertainty attached

Review a number with the words that govern it. “Up to eight” gives an upper bound; “at least eight” gives a lower bound. “Eight more” is different from “eight in total.” “About eight” should not become an exact promise. A range also needs both endpoints and the relationship between them, not a concatenated run of digits.

Changing notation is different from converting a unit. Replacing a decimal point with the appropriate decimal comma may preserve the value. Replacing metres with feet requires a numerical conversion and a decision about precision. Do not silently make that second change while tidying captions. If localization requires it, document the approved equivalent and have the responsible reviewer check it separately.

Preserve meaningful spoken corrections. If a presenter says “twenty-five—sorry, two and a half,” the correction may explain a visible hesitation or another person’s reaction. Do not automatically erase the first number. If an instructional recording contains an unresolved error, ask the owner to resolve the recording or accompanying correction rather than making captions quietly contradict the audio.

Worked example: a ribbon quantity review

This fictional example describes an original craft demonstration, not a Polyglot test. The presenter says, “Cut two and a half metres of ribbon. Make at least eight loops.” A draft reads “Cut 25 metres of ribbon. Make up to eight loops.” The first error changes the length; the second reverses the boundary even though the number eight is unchanged.

Use a small review sheet for the affected passage. Keep the video revision and cue locator, the exact spoken quantity, the draft, the intended meaning and the approved wording. Add the reviewer and decision status in a real project. If the audio is unclear, keep the decision unresolved instead of copying a plausible value from an unrelated pattern.

Video: ribbon-demo-v3
Cue 12, 00:18
Spoken: two and a half metres
Draft: 25 metres
Meaning: 2 + 1/2 metres
Reviewed: 2.5 metres

Cue 13, 00:22
Spoken: at least eight loops
Draft: up to eight loops
Meaning: eight or more
Reviewed: at least eight loops

Resolve dates, times and currency without inventing context

A numeric date can be ambiguous across audiences. If the recording clearly says “April fifth,” writing the month name can retain that clarity; replacing it with 04/05 can introduce a new question. If the recording only shows 04/05 and the meaning is uncertain, confirm it with the owner. Do not guess the month from your own computer’s regional setting.

For clock times, retain information needed to distinguish morning from evening when the speaker supplies it. A time-zone conversion is a separate editorial change, not punctuation cleanup. Never infer a time zone from the language of the subtitles. When a recording lacks context needed for a current event announcement, resolve that in the approved publication materials.

Currency symbols also need context. Do not assume every dollar amount is US dollars, or replace a named currency with a different one for the target audience. If a translation needs an explicit currency name for clarity, verify it against the source and the agreed translation brief. The review task is to preserve the stated amount, not calculate purchasing power or update historical prices.

Edit caption text without localizing the file syntax

An SRT file has cue identifiers, timestamp lines and caption text. The commas in its millisecond timestamps are structural syntax; they are not the decimal convention of the subtitle language. Never run a whole-file comma-to-point or point-to-comma replacement to localize quantities. The number at the top of a cue is also not spoken content.

The sample below keeps a fixed SRT time range while the caption text uses the fictional production’s chosen decimal-point style. A translated track can use a different approved number style in its text while retaining valid file timing syntax. Verify the export after editing; the linked SRT validation guide covers cue accounting and structural checks.

In Polyglot, review text against the media where available, then review each translated language separately. Source corrections can mark dependent translations for review without replacing completed translations automatically. Structural checks do not establish that a quantity, unit or date still means the right thing. Keep the working project and exported delivery revision distinct.

12
00:00:18,000 --> 00:00:21,000
Cut 2.5 metres of ribbon.

Approve the value the viewer actually reads

Finish with the exact exported file in the receiving player. Check decimals, minus signs, fraction characters and unit wording at the normal viewing size. Keep a value and its unit together where practical. If a dense quantity cannot be read in time, review phrasing or timing with the video; do not delete a qualification just to shorten the cue.

For each translated track, ask the reviewer to state the quantity in ordinary words. In the example, the answers should still be two and a half metres and eight or more loops. This makes a misplaced separator or reversed boundary easier to notice than a quick visual comparison of digits. It is a proposed review exercise, not a claim of tested translation accuracy.

Record the approved video revision, language, subtitle filename and unresolved questions. Hold delivery when a meaning-changing quantity remains uncertain. Number review complements the broader checks for dialogue, meaningful sounds, speaker information and timing; it cannot by itself establish that a complete caption track is ready.

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