File formats and compatibility

Nixt Sheets works in Excel’s own workbook format. This page explains what it opens, what it saves, and what a workbook keeps when it moves between Nixt Sheets and Excel.

Files you can open

Extension	What it is	Opens as
`.xlsx`	Excel workbook	A workbook
`.xlsm`	Excel workbook with macros	A workbook. Macros are kept but never run.
`.xltx`	Excel template	A workbook
`.xltm`	Excel template with macros	A workbook. Macros are kept but never run.
`.csv`	Comma-separated values	A workbook with one sheet
`.tsv`	Tab-separated values	A workbook with one sheet

For other file types:

Extension	Why	What to do
`.xls`, `.xlt`	Excel 97–2003 binary workbooks are a different format, not an older version of `.xlsx`	Open the file in Excel once and save it as `.xlsx`
`.ods`	Nixt Sheets works in Excel’s workbook formats	Export it as `.xlsx` from the app that made it
`.docx`, `.pptx`, `.pdf` and other document types	Nixt Sheets opens spreadsheets only	Use Nixt Writer, Nixt Slides or Nixt PDF

See Getting started for the messages you see.

Files you can save

Format	How	Contents
`.xlsx`	Save, or Save a copy as › Excel workbook	The whole workbook
`.pdf`	Save a copy as › PDF	Every visible sheet, paginated
`.csv`	Save a copy as › Comma-separated values	The current sheet’s displayed values
`.tsv`	Save a copy as › Tab-separated values	The current sheet’s displayed values
`.html`	Save a copy as › Web page	The current sheet as a table

Details of the PDF, CSV, TSV and HTML exports are in Printing and exporting.

How saving works

An .xlsx file is a package of many parts. When you save, Nixt Sheets rewrites the parts that describe the sheets — cells, formatting, structure — and the parts for the features listed below. Every other part of the package is written back exactly as it was read. That includes parts Nixt Sheets doesn’t use, such as a macro project, custom XML, embedded fonts, and the caches behind Excel PivotTables.

Formulas are saved together with their latest results, and the workbook is recalculated before saving, so another app opening the file sees correct values straight away.

What round-trips with Excel

These are read from a workbook and written back in Excel’s own format, so they appear in Excel after you save:

Area	What is kept
Cells	Values and formulas, including dynamic arrays, structured references, 3-D references and names that hold a LAMBDA
Formatting	Fonts and their names, sizes, bold, italic, single and double underline, strikethrough, colours, fills, all seven border styles with colours, diagonal borders, horizontal and vertical alignment, wrap, indent, rotation, text direction, number formats, locked cells
Structure	Sheets and their order, sheet names, tab colours, hidden sheets, column widths, row heights, default column width, hidden rows and columns, merged cells, frozen panes, grid line setting, right-to-left sheets
Names	Defined names, print areas and print titles
Tables	Tables with their names, styles, style options, totals rows and totals functions
Data	Filter ranges and their criteria, data validation rules, conditional formatting rules and their formats, scenarios
Outlines	Row and column groups, folded groups, summary position
Review	Notes, threaded comments with replies and resolved state, sheet protection, workbook structure protection, editable ranges
Page setup	Paper, orientation, margins, scaling and fit to pages, centring, page order, grid line and heading printing, headers and footers, page breaks you inserted
Charts	Charts, with their types, series, titles, axis titles, legends, data labels, grouping, secondary axes, trendlines and error bars. A chart you didn’t change is written back exactly as it was read.
Sparklines	Sparkline groups and their options
Pictures and shapes	Pictures, the 13 shapes, text boxes, their positions, sizes, rotation, fill, outline, words, names, descriptions and front-to-back order
Themes	The workbook theme. A theme you didn’t change is written back exactly as it was read.
Background	The sheet background picture
Links to other workbooks	The links and the values remembered from the other workbooks
Checkboxes	Checkbox cells, which other apps without checkboxes show as TRUE and FALSE

Also saved in the workbook

These Nixt Sheets features are saved in the workbook too, so they are there the next time you open it in Nixt Sheets:

PivotTable definitions
Slicers and timelines
Queries and their steps
Custom fill lists
Object groups

Macros

Macros in .xlsm and .xltm workbooks are never run. When you save, the macro project is written back unchanged.

Dates

Workbooks use Excel’s date system: dates are numbers counted from 1 January 1900, with 1900 treated as a leap year, as Excel treats it. Workbooks that use the 1904 date system, common in files from older Mac versions of Excel, keep it.

CSV and TSV files

A .csv or .tsv file holds text only: no formatting, formulas, sheets or objects.

Opening: the delimiter is detected from the first lines — comma, tab, semicolon or pipe — and each value is read as if you had typed it, so numbers become numbers. The text is read as UTF-8.
Exporting: the current sheet’s values are written as they are displayed, as UTF-8.

Because opening reads values the way typing does, a code with leading zeros such as 00123 stays text — see Entering and editing data.