formulagym.com · Index

Understand any formula by playing with it.

Small, editable playgrounds for the formulas you actually use — change the inputs, watch the result recompute, keep the intuition.

Formula Gym turns each formula into a hands-on sandbox. Instead of memorising syntax, you change the arguments and watch the result resolve in real time — so when you hit a real problem, you reach for the right formula because you already know what each piece does. Today the catalogue covers spreadsheet functions (VLOOKUP, SUMIF, and more on the way). Math identities, physics equations, and trading indicators will follow on their own subdomains as the library grows.

01 · Excel & Google Sheets

Excel & Google Sheets formulas →

Browse the full index with categories, or jump straight to a function below. Topics on math, physics, and trading indicators will move to their own subdomains as they grow.

SUMIF

Add up numbers — but only the rows that match a condition.

VLOOKUP

Find a value in a table and return data from the same row.

XLOOKUP

The modern successor to VLOOKUP. Exact match by default; looks either way.

INDEX + MATCH

Two functions that compose into the most flexible lookup pattern.

SUMIFS

SUMIF with multiple conditions. Different argument order — watch out.

IF

The simplest decision maker — return one value if TRUE, another if FALSE.

COUNTIF

Count how many cells in a range meet a single condition.

COUNTIFS

COUNTIF with multiple conditions — AND'd together, up to 127 pairs.

IFERROR

Catch any formula error and substitute a clean fallback value.

AVERAGEIFS

Multi-condition averaging. Returns #DIV/0 when no rows match — not 0.

TEXTJOIN

Join a range with any delimiter. The modern replacement for CONCATENATE.

ROUND

Round to a digit count. Positive for decimals, negative for tens/hundreds.

UNIQUE

Dedupe a range — or find values that appear exactly once.

FILTER

Keep rows that pass a boolean test. The dynamic-array AutoFilter.

DATE

Build a date from year, month, day — including the overflow rollover trick.

LEFT

Take the first N characters of a text value. Pairs with FIND for dynamic splits.

SUBSTITUTE

Replace text by value — every match, or just the Nth one with instance_num.

MAX

Largest numeric value in a range. Silently skips text, blanks, and booleans.

MIN

Smallest numeric value in a range — mirror of MAX, same silent skips.

AVERAGE

Arithmetic mean of a range. Skips text and blanks; zeros are counted.

TRIM

Strip leading/trailing spaces and collapse internal runs — import cleanup.

RIGHT

Take the last N characters of a text value — mirror of LEFT.

EOMONTH

Last day of a month offset by N. Leap-year aware — no 28/29/30/31 logic.

MID

Cut a substring from any position — month from a date, domain from an email.

SORT

Reorder a range by any column, ascending or descending — live, spilled, no menu.

IFS

Flat cascade of test/value pairs. Modern replacement for deeply nested IF.

LEN

Count characters in a value. Pairs with TRIM to diagnose hidden whitespace.

FIND

Locate a substring's position. Feeds LEFT/MID/RIGHT for dynamic text splits.

SUM

The foundational total. Skips blanks and text; underpins every SUMIF / SUMIFS.

TODAY

Current date as a live value. Drives deadlines, age, freshness flags.

IFNA

Surgical sibling of IFERROR. Catches #N/A only; real bugs stay visible.

CONCATENATE

Legacy text joiner. Still ubiquitous in old sheets; superseded by CONCAT/TEXTJOIN.

COUNT

Count numeric cells only. Diagnoses text-stored-number bugs paired with COUNTA.

COUNTA

Count every non-blank cell. Natural for 'how many rows exist' questions.

EDATE

Shift a date by N months. Clamps Jan 31 + 1 month to Feb 28 automatically.

ROUNDUP

Always rounds away from zero. Capacity planning, pagination, price ceilings.