Check an XLSX import in Proton Sheets before relying on it

Open a copy of your workbook in Proton Sheets, then check whether its important values and formulas still work. This walkthrough gives you a small fictional example with expected answers, so you can spot a changed ID, a formula replaced by a number or a missing chart before using the imported copy.

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Proton Sheets Summary showing 10 total units, 70.00 base total, 87.50 adjusted total and multiplier 1.25

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The fictional workbook starts with 10 total units, a base total of 70.00 and an adjusted total of 87.50.

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You need a Proton account to edit the imported workbook. Proton Free includes Sheets and is enough for this example. This guide contains an affiliate link. If you buy a qualifying paid subscription through it, HoldMyTwist may earn a commission. Free registration alone does not earn us a commission. You can choose Proton Drive Free for this workbook check (opens in a new tab), or sign in to your existing Drive account (opens in a new tab).

Use a desktop-sized browser and keep your original file. If you only want to store an XLSX in Drive, you do not need to convert it into an editable Sheet.

1. Record what should survive

Before uploading, open the original in the spreadsheet app you normally use. Write down the sheet names, a few exact values, important formulas and any chart or other object you need. Work with a separate copy, especially when you will change inputs to check calculations. Only upload information you are comfortable storing with Proton.

Download the fictional practice ZIP, extract it, and use source-fixture.xlsx. The ZIP also includes a short readme. The workbook contains two sheets, Summary and Records, with three invented rows. Its values are unitless. Keep the downloaded original unchanged.

For this example, your starting checks are:

• Sheet names: Summary and Records
• Text IDs: 0012, 0105 and 0007
• Displayed dates: 2026-02-03, 2026-03-14 and 2026-12-31
• Summary cells B5, B6 and B7: 10, 70.00 and 87.50
• Multiplier in Summary B9: 1.25
• A line-chart object in the original Summary sheet

For your own workbook, include an output you can calculate independently. A matching total at first glance does not tell you whether a formula will respond to a changed input.

2. Open the copy in Proton Sheets

1. In Proton Drive, open the folder where you want to keep the test file and click Upload file.
2. Choose your XLSX and wait for the upload to finish.
3. Open the uploaded file, then choose Open in Proton Sheets.
4. Check that the expected sheet tabs appear at the bottom. Keep the original XLSX as well as the converted copy.

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Proton Drive spreadsheet preview with the Open in Proton Sheets button

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Proton also documents File > Import inside Sheets, with different choices for where to place the imported data and how to convert text. Do not assume those options were applied to a file opened from Drive.

3. Compare IDs, dates and formulas

1. Open Records. Compare each example ID and displayed date with your list. The leading zeros in 0012, 0105 and 0007 should remain visible.
2. Check Summary against the starting totals. If something differs, stop and compare the affected cells with the unchanged original.
3. Return to Records. Click cell G2 and read the formula bar above the grid. It should contain =F2*Summary!$B$9 or the same reference with harmless quoting around the sheet name.

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Records sheet showing text IDs 0012, 0105 and 0007 beside three calendar dates

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Proton Sheets formula bar showing equals F2 times Summary exclamation dollar B dollar 9

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G2 uses the base value in F2 and the fixed multiplier in Summary B9.

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The dollar signs keep B9 fixed when the formula is copied. If G2 shows only 31.25 in the formula bar, the expected formula is missing even though its displayed answer looks right. In Summary, B5 should sum Records D2:D4, B6 should sum Records F2:F4 and B7 should sum Records G2:G4.

Check date calculations before relying on the imported copy. In the converted fictional practice workbook, use the empty cells in Summary for these two checks. Keep the downloaded original unchanged.

1. In Summary A12, type Numeric dates. In B12, enter =COUNT(Records!B2:B4) and press Enter.
2. B12 should show 3, counting all three imported date cells as numbers.
3. In A13, type Next day. In B13, enter =TEXT(Records!B2+1,"yyyy-mm-dd") and press Enter.
4. B13 should show 2026-02-04, one day after the date in Records B2.

COUNT counts numeric cells. A result of 3 does not tell you whether those dates are correct, so compare the displayed dates with the original too. Both calculations passed in our imported practice copy.

If your results differ, compare the affected cells and formulas with the original. Do not overwrite the original to force the expected answers. In your own workbook, choose genuinely empty cells and date calculations you can verify independently. These two checks do not cover every formula or date format.

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Proton Sheets Summary showing three numeric dates and a next-day result of 2026-02-04.

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The imported practice copy returns 3 numeric dates and 2026-02-04 after adding one day to Records B2. The formula for B13 is visible above the grid.

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4. Change one input, then restore it

For the practice workbook, leave Summary B9 at 1.25.

1. Open Records, click D2, type 4 and press Enter. You are changing Amber's units from 2 to 4.
2. Check that F2 becomes 50.00 and G2 becomes 62.50. Those come from 4 × 12.50, then 50 × 1.25.
3. Open Summary. Its totals should now be 12, 95.00 and 118.75.
4. Return to Records, set D2 back to 2 and press Enter. Check that Summary returns to 10, 70.00 and 87.50.

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Proton Sheets Summary showing changed totals of 12 units, 95.00 base value and 118.75 adjusted value

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After changing Amber's units to 4, the linked Summary totals become 12, 95.00 and 118.75.

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For your own workbook, choose an input you can change and restore, and calculate the expected effect first. Check the affected outputs, then restore the original input and confirm that the original outputs return. If you cannot explain a result, keep using the original workbook while you investigate.

5. Check required charts and decide

Look for every chart or other object you recorded before importing. Check that the intended data is still represented and that an object you need to edit is actually editable.

The practice file's line chart did not appear in our imported copy, although its cells recalculated. We do not know why the chart was missing. This single generated XLSX does not establish how charts from other workbooks will behave. Proton Sheets supports creating and editing charts; an imported chart still needs its own check.

If a required chart is missing, keep using the original for that task. Creating a replacement would be a separate job.

Passing these sample checks does not cover features your workbook uses beyond them. Keep the original file even if the checks you need pass.

If you also need an offline or Excel copy

Proton documents File > Download for exporting a Sheet. Download an XLSX and check it in the app you intend to use before relying on that file. A native Sheet placeholder in a synced Drive folder is not an offline spreadsheet. This guide checks the import in Proton Sheets. We have not verified an exported copy in Excel or LibreOffice.

If you want to run the example before moving a real workbook, start with Proton Drive Free (opens in a new tab) and use the fictional practice file above. Keep your original workbook until the checks you need pass.

Sources: Proton Sheets import and export (opens in a new tab), formulas and cell references (opens in a new tab), charts (opens in a new tab), and Proton Drive plans (opens in a new tab).