Formulas & Functions

CAGR formula in Excel: (end/start)^(1/years)-1, RRI and POWER, the years mistake, CAGR vs average growth, months and dates, negative values. Free calculator.

Running total in Excel: running balance, expanding SUM, blank rows, a table running total, totals by category or month, and YTD vs target. Free workbook.

Calculate age in Excel from a date of birth with DATEDIF: years, months and days, as of today or any date, YEARFRAC, #NUM! fixes, next birthdays. Free workbook.

Sales tax formula in Excel: add tax to a price, remove tax from a total (reverse), combined rates, taxable lines, the journal entry and VAT. Free calculator.

Compound interest formula in Excel with monthly contributions: P*(1+r/n)^(nt), the FV function, start-of-month deposits, daily compounding, free calculator.

Calculate NPV and IRR in Excel the right way, avoid the year-0 NPV mistake, and add payback, discounted payback, XNPV and XIRR. Free calculator.

Sum timestamped transactions for a date range without losing afternoon, evening, or last-minute entries on the end date. The free workbook calculates $609.50 across 7 transactions from Nov…

Use IFERROR in Excel to show a blank or message instead of #DIV/0! and #N/A, learn when IFNA is safer, get blank instead of 0 and total around…

Use LET to give intermediate calculations meaningful names, simplify long formulas, and avoid repeating an expression. Build a quote total step by step, then check the result against…

Find and fix a circular reference in Excel: open the reference list, trace the formula loop, repair the source, and confirm the workbook recalculates safely.