Guides

Clean, check and trust your spreadsheet data

Practical guides on the problems that quietly damage Excel and CSV files: messy data, dates, phone numbers, duplicates, broken imports and data entry accuracy. Every guide has the exact formulas, the traps to avoid and the sources behind the numbers.

01Excel data cleaningHow to Clean Messy Excel Data: A Step-by-Step GuideThe fixed order that stops one fix from undoing another, with the formulas for every step.10 min read 02Text and numbersHow to Keep Leading Zeros in Excel and CSV (ZIP Codes, IDs)Why Excel turns 02134 into 2134, how to get the zeros back, and how to stop it happening when you open a CSV.5 min read 03CSV and importsHow to Clean a CSV File Before Importing It Into a CRMSeven fixes that prevent duplicate contacts, rejected rows and scrambled characters, and the 10-row test to run first.4 min read 04DatesHow to Fix Dates in Excel and CSV Files (Mixed Formats)Text dates, day-month swaps, two-digit years and the one rule that makes dates safe to share.8 min read 05Phone numbersHow to Fix Phone Numbers in Excel: Format and Country CodesLeading zeros, 9.19E+11, country codes and the international format that every system accepts.6 min read 06DuplicatesHow to Remove Duplicates in Excel Without Losing DataExact, near and partial duplicates: decide what counts, mark before you delete, keep the best record.6 min read 07DuplicatesHow to Find and Highlight Duplicates in ExcelFind repeats safely first: highlight them, count them, keep the first one, and spot the near-duplicates Excel does not see.3 min read 08NamesHow to Standardize Names in Excel: Proper Case and ExceptionsWhat PROPER gets wrong, how to protect names that are already right, and how to flip "Smith, John" into "John Smith".4 min read 09Email addressesHow to Fix Email Typos in Excel: gmial.com, .con and Missing @The typos that make campaigns bounce, and the formulas and checks that fix them without guessing.4 min read 10Email addressesHow to Clean an Email List Before You Send a CampaignA five-step routine that removes the avoidable bounces from a list without deleting anyone you should keep.3 min read 11NamesHow to Split Full Names into First and Last Name in ExcelFlash Fill, Text to Columns and formulas for splitting names, and the names that trip each one up.4 min read 12Text cleanupHow to Remove Extra Spaces in Excel (TRIM, CLEAN and Non-Breaking Spaces)Why TRIM sometimes does nothing, and the one formula that removes every kind of stray space.3 min read 13Text cleanupHow to Remove Special Characters and Line Breaks in ExcelThe characters you cannot see, the smart quotes you can, and the exact formula or shortcut that removes each one.4 min read 14NumbersHow to Convert Text to Numbers in Excel (Numbers Stored as Text)Why sums show zero, why numbers sit on the left, and four ways to turn text back into real numbers.3 min read 15Excel data cleaningHow to Clean Data with Power Query in Excel (Step by Step)Record your cleaning steps once and replay them on every new file, without formulas and without touching the original data.4 min read 16Comparing dataHow to Compare Two Lists in Excel and Find What Is MissingFind the names, IDs or emails that are in one list and not the other, with formulas that scale.3 min read 17CSV and importsFix Garbled Characters and Broken CSV Imports (UTF-8)UTF-8, delimiters, leading zeros, quotes and a checklist that makes a file safe to import.7 min read 18Data entryData Entry Accuracy: How to Check, Measure and Improve ItWhat the research says about error rates, why proofreading fails and the checks that actually work.9 min read

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