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# Convert text to numbers and Unix timestamps to dates

> Convert text like $1,234.56 or 45% to numbers in Mammoth, see which currency symbols and separators work, and turn Unix timestamps in any unit into dates.
>
> Applies to: Where: View › Describe your transformation › Column Management › Convert Column Type

**Convert Column Type** to **Number** pulls the number out of formatted text, and Number to **Date** reads Unix timestamps. When a value can't be converted, the cell becomes empty (NULL). For the task's steps and settings, see [Convert text to dates and numbers](https://mammoth.io/docs/learn/clean-and-shape/convert-column-type/).

## Convert text to a number

Mammoth pulls the number out of formatted text. It strips a currency symbol in front of the number, comma thousand separators and a percent sign.

| Input type | Example | Result |
| --- | --- | --- |
| Plain number | 1234 | 1234 |
| With decimals | 1234.56 | 1234.56 |
| Currency prefix | $1,234.56 | 1234.56 |
| Negative with currency | \-$1,234.56 | \-1234.56 |
| Negative (leading) | \-1,234.56 | \-1234.56 |
| Negative (after the symbol) | $-1,234.56 | \-1234.56 |
| Percentage | 45% | 45 |
| Leading or trailing spaces | "  $1,234.56  " | 1234.56 |

## Currency symbols Mammoth recognises

These 5 symbols are recognised and stripped when they come **before** the number:

| Symbol | Currency | Example input | Result |
| --- | --- | --- | --- |
| **$** | US Dollar | $1,234.56 | 1234.56 |
| **€** | Euro | €1,234.56 | 1234.56 |
| **£** | British Pound | £1,234.56 | 1234.56 |
| **¥** | Japanese Yen / Chinese Yuan | ¥1234 | 1234 |
| **₹** | Indian Rupee | ₹1,234.56 | 1234.56 |

## Thousand separators and European number formats

Mammoth removes comma thousand separators before converting. Standard grouping (1,234,567) and Indian-style grouping (12,34,567) both work. 1,234,567.89 and 1234567.89 both become 1234567.89.

European format isn't supported. Numbers that use a period as the thousand separator and a comma as the decimal (for example `1.234.567,89` or `€1.234,56`) aren't recognised and convert to empty. Use [Find & Replace](https://mammoth.io/docs/learn/clean-and-shape/find-and-replace/) to change them to comma thousands and a period decimal first (`1.234.567,89` → `1,234,567.89`), then convert to Number.

## Limits on converted numbers and timestamps

| Limit | Value |
| --- | --- |
| Decimal places stored after a text-to-number conversion | Up to **8** (NUMERIC(38,8)). 1234.56789012345 is stored as 1234.56789012. Numbers are rounded to 8 decimal places. |
| Currency symbols recognised | 5: $, €, £, ¥, ₹, in front of the number only |
| Valid Unix timestamp range (seconds) | \-62,135,596,800 to 253,402,300,799 |

## Convert a Unix timestamp to a date

When you convert a Number column to Date, Mammoth detects the time unit from the size of each value. You don't need to say which unit you have, because systems differ: JavaScript's `Date.now()` and Java's `System.currentTimeMillis()` return milliseconds (1735689600000), while Python's `time.time()` returns seconds (1735689600).

| Value range | Detected unit | How it's read | Example input | Result |
| --- | --- | --- | --- | --- |
| \-62,135,596,800 to 253,402,300,799 | **Seconds** | Unix timestamp (standard) | 1735689600 | 2025-01-01 00:00:00 |
| \-62,135,596,800,000 to 253,402,300,799,000 | **Milliseconds** | Divided by 1,000 | 1735689600000 | 2025-01-01 00:00:00 |
| \-62,135,596,800,000,000 to 253,402,300,799,000,000 | **Microseconds** | Divided by 1,000,000 | 1735689600000000 | 2025-01-01 00:00:00 |
| \-62,135,596,800,000,000,000 to 253,402,300,799,000,000,000 | **Nanoseconds** | Divided by 1,000,000,000 | 1735689600000000000 | 2025-01-01 00:00:00 |
| Outside all ranges | | **NULL** (invalid) | 99999999999999999999999 | (empty cell) |

Two edge cases: `0` is read as seconds and gives 1970-01-01 00:00:00 (the Unix epoch start). `-86400` gives 1969-12-31 00:00:00, one day before the epoch.

## Troubleshooting text to number conversions

| Problem | Cause | Fix |
| --- | --- | --- |
| All cells become empty | No numbers found in the text | Check that the text contains numbers, not only words. |
| Some cells are empty | Unsupported currency symbol or format | Only €, $, ¥, £ and ₹ are recognised. |
| "1,234.56€" fails | Currency symbol after the number | Put the symbol in front: "€1,234.56". |
| "1.234,56" fails | European format | Use Find & Replace to make it "1,234.56", then convert. |
| "25%" gives 25 | The % sign is stripped | You get the number. Convert to **Percentage** or format the result as a percentage if needed. |

## Troubleshooting Unix timestamp conversions

| Problem | Cause | Fix |
| --- | --- | --- |
| All cells become empty | Values outside the valid timestamp range | Check the numbers. Valid range: -62,135,596,800 to 253,402,300,799 seconds. |
| Date is in 1970 when it should be 2025 | The unit was detected wrongly | Check the source system's convention (seconds or milliseconds). |
| Very old or future dates | Read as a different unit | Check the input really is a Unix timestamp. Other numbers convert wrongly. |

## Related

- [Convert text to dates and numbers](https://mammoth.io/docs/learn/clean-and-shape/convert-column-type/): the Convert Column Type steps and settings.
- [Convert text to a date with format codes](https://mammoth.io/docs/learn/clean-and-shape/convert-text-to-date/): when the date is text.
- [Column types, IDs, currency and percentages](https://mammoth.io/docs/learn/clean-and-shape/column-types/): what each type means and where it shows.
- [Find and replace values](https://mammoth.io/docs/learn/clean-and-shape/find-and-replace/): fix separators before converting.

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Source: https://mammoth.io/docs/learn/clean-and-shape/convert-numbers-and-timestamps.md · Updated: 2026-11-08