Make a list of numbers, letters, or dates in one step. Choose the separator and quotes, so the list pastes straight into a spreadsheet, a file, or a SQL query.
Use 2 for every other number or a negative step to count down. Whole numbers only.
For a SQL IN list, choose Comma, a single quote, and ( ). For a JavaScript or Python list, choose Comma + space, a double quote, and [ ].
File names
Use Numbers with IMG_ as the prefix and .jpg as the suffix.
SQL IN list
Comma, single quote, and ( ) give you a list you can paste as is.
Date lists
Set Dates with a step of 7 for the same weekday every week.
A sequence generator for numbers, letters, and dates
Set a start, a count, and a step, and the tool builds the list for you. It makes numbers such as 001, 002, 003, letters that run A, B, C to Z and then AA, AB, and dates that move forward or back by a number of days.
A prefix and a suffix are added to every item, so IMG_ and .jpg give you file names. The output panel sets the separator, the quote character, and an outer bracket, which means the same list can be one item per line or a ready-to-paste comma-separated list.
Everything runs in your browser. One run makes up to 1,000 items.
Lists people build with it
File names for batch renaming
Set the prefix to IMG_ and the suffix to .jpg to get IMG_001.jpg, IMG_002.jpg, and so on, ready for a rename tool or a script.
ID lists for a SQL query
Choose Comma, a single quote, and ( ) to get a list such as ('001','002','003') that you can paste after IN.
Dates for a schedule or log
Pick a start date and a step of 7 for the same weekday every week, or use the weekday format to start a calendar sheet.
Letters for outlines and answer choices
Generate A, B, C labels for survey options or an outline. Past Z the list continues with AA and AB.
How to build a list in 5 steps
- Choose Numbers, Letters, or Dates as the sequence type.
- Enter the start, the count, and the step.
- For numbers, set the digits for leading zeros. For dates, pick a date format.
- Add a prefix or suffix if you need one, then choose the separator, quotes, and brackets.
- Check the preview and click Copy, or use the download button.
Note: The preview updates with every change. A negative step counts down for numbers and goes back in time for dates.
What the settings do exactly
- Count: one run makes at most 1,000 items. A larger value is cut to 1,000 and a notice appears.
- Leading zeros: the number is padded on the left with zeros up to the digits you set. A longer number is not cut off, and a minus sign stays at the front.
- Whole numbers: start and step are whole numbers. A decimal is cut toward zero, so a step of 1.9 acts as 1.
- Letters: 1 is A, 26 is Z, 27 is AA, and 703 is AAA. If a step takes the position below 1, those items show as A and a notice appears.
- Dates: dates are calculated in UTC, so the time zone of your device does not shift a date. Month ends, year ends, and leap days are counted correctly.
- Prefix, suffix, and quotes: the prefix and suffix go on each item first. The quote then wraps the whole item, and the bracket wraps the whole list.
Settings for common lists
Each row shows the settings to use and the output you get.
| List | Settings | Output |
|---|---|---|
| Zero-padded numbers | Numbers, 3 digits | 001, 002, 003... |
| IDs with a prefix | Numbers, 4 digits, prefix ID_ | ID_0001, ID_0002... |
| Every fifth number | Numbers, no padding, step 5 | 1, 6, 11, 16... |
| Countdown | Numbers, start 10, step -1 | 10, 9, 8, 7... |
| Letters | Letters, start 1 | A, B, C... Z, AA, AB... |
| Dates | Dates, 05/13/2026 format | 05/13/2026, 05/14/2026... |
| Date plus a number | Dates, 20260513 format, suffix -01 | 20260513-01, 20260514-01... |
| SQL IN list | Numbers, Comma, single quote, ( ) | ('001','002','003') |
| Spreadsheet column | Any type, New line | One item per line |
Why leading zeros matter for sorting. A file list sorted as text puts 10 before 2. Padded names such as 002 and 010 sort in the order you meant.
Date plus a number. If the date stays fixed and the number grows, use Numbers and put the date in the prefix. If the date moves each row, use Dates with the 20260513 format and put -01 in the suffix.
Column or row. In Excel and Google Sheets, a list separated by new lines pastes down a column, and a list separated by tabs pastes across a row.
Output formats for spreadsheets, SQL, and code
How to set the separator, quotes, and brackets so the list needs no editing after you paste it.
A SQL IN list or a code array without editing
An IN list needs commas between values, quotes around text values, and parentheses around the whole list. Set the separator to Comma, the quote to a single quote, and the wrap to ( ), and the list comes out as ('001','002','003'). For a JavaScript or Python list, use Comma + space, a double quote, and [ ].
Pasting into a spreadsheet as a column or a row
New line separators fill cells down a column, and Tab separators fill cells across a row. Excel treats 001 as the number 1 in a General cell, so format the target cells as Text before you paste to keep the zeros.
How letters continue after Z
The letter sequence has no zero digit, so the step after Z is AA, not BA. The positions are 26 for Z, 27 for AA, 52 for AZ, 53 for BA, 702 for ZZ, and 703 for AAA. This matches spreadsheet column names.
Building IDs that combine a date and a number
For IDs such as 20260513-01, pick Dates with the 20260513 format and enter -01 as the suffix. The date changes on each row and the suffix stays the same. If you need the date fixed and the number to grow, use Numbers and type the date as the prefix.
Problems that break a generated list
Leading zeros vanish after pasting into Excel
You paste 001, 002, 003 into a General cell and see 1, 2, 3. Excel reads the text as numbers and drops the zeros.
💡 See the solution▼
Numbers sort as 1, 10, 100, 2
Names without padding sort as text, so 10 lands before 2. A folder of files named 1 to 100 shows up out of order.
💡 See the solution▼
Reformatting a list by hand for SQL
A list with one value per line has to be turned into quoted, comma-separated values by find and replace. A missed quote or a trailing comma breaks the query.
💡 See the solution▼
Wrong letters after Z
Counting by hand, the item after Z is easy to get wrong, and the next step after ZZ is even easier to miss.
💡 See the solution▼
Sequence generator FAQ
Q.How do I generate a list of numbers with leading zeros?
A. Keep the type on Numbers, turn on Leading zeros, and set the number of digits. A start of 1 with 3 digits gives 001, 002, 003, and so on. Set the count to say how many items you want.
Q.Can it generate letters like A, B, C, then AA, AB?
A. Yes. Choose Letters. After Z the sequence goes to AA, AB, AC, the same rule spreadsheets use for column names. Start is a number: 1 is A, 26 is Z, and 27 is AA, so enter 27 to begin at AA. You can switch to lowercase.
Q.Can I generate a list of dates?
A. Yes. Choose Dates, pick a start date, and set the count. A step of 1 moves one day at a time, 7 gives the same weekday every week, and -1 counts back. Month ends, year ends, and leap days are handled for you. You can show dates as 2026-05-13, 05/13/2026, May 13, 2026, 20260513, 05/13, or with the weekday.
Q.How do I get a comma-separated list or a SQL IN list?
A. Set Separator to Comma, Quote each item with to a single quote, and Wrap the whole list in to ( ). Three numbers with 3 digits come out as ('001','002','003'). For a JavaScript or Python list, use Comma + space, a double quote, and [ ].
Q.How many items can it generate at once?
A. Up to 1,000. If you enter a larger count, the tool uses 1,000 and shows a notice. For a longer list, change the start value and generate again.
Q.What happens when a number is longer than the digits I set?
A. Nothing is cut off. With 3 digits, the number after 999 is written as 1000. A negative number keeps its minus sign in front, as in -005.
Q.Can I count down?
A. Yes. Enter a negative step. A start of 10 with a step of -1 gives 10, 9, 8, and so on. The same works for dates. For letters, anything below 1 is shown as A.
Q.Why does Excel drop the leading zeros when I paste the list?
A. Excel reads 001 as the number 1 in a General cell and shows it as 1. Format the cells as Text before you paste, and the zeros stay.
Q.What file does Download create?
A. A .csv file when the separator is Comma or Comma + space, and a .txt file otherwise. The name looks like serial_number_10.txt. The CSV starts with a byte order mark so Excel reads non-ASCII text correctly. The .txt file has none.
Q.Is anything sent to a server?
A. No. The list is generated in your browser with JavaScript. Your settings are not uploaded or saved.
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