Average Calculator (Mean, Median, Mode)

This average calculator computes the mean, median, mode, range and sum for any list of numbers in one step. The 'average' people mean is usually the mean, but the median and mode often tell you more. Paste any list of numbers here and get all three, plus the range, sum and count, in a single step — making it a complete average calculator for school, work or quick number crunching.

The three averages

mean   = sum ÷ count
median = middle value when sorted (average the two middle values if the count is even)
mode   = most frequent value(s), or none if nothing repeats

Each measures 'typical' in a different way, and they diverge whenever the data is skewed.

Why the median matters

A single huge outlier drags the mean but barely moves the median. Salaries, house prices and reaction times are classic examples where the median is the more honest summary — which is why this tool shows both side by side.

Worked example

For the list 2, 4, 4, 4, 5, 5, 7, 9:

count  = 8
sum    = 2+4+4+4+5+5+7+9 = 40
mean   = 40 ÷ 8 = 5
sorted = 2, 4, 4, 4, 5, 5, 7, 9
median = (4 + 5) ÷ 2 = 4.5   (even count, so average the two middle values)
mode   = 4                   (appears three times; 5 appears only twice)
range  = 9 − 2 = 7

All three averages land close together, which is what a symmetrical set looks like. When they pull apart, that gap is the interesting result rather than a nuisance.

One number that breaks the average

Take 3, 4, 5, 6, 7. The mean is 5 and the median is 5 — they agree exactly. Now add 100:

mean   = (3+4+5+6+7+100) ÷ 6 = 125 ÷ 6 = 20.8333
median = (5 + 6) ÷ 2 = 5.5
mode   = None (every value now appears once)

The mean more than quadrupled on the strength of a single value while the median moved by half. That is the entire argument for reporting both, and it is why salary, house-price and response-time data are usually summarised by their median.

The Count line in the breakdown deserves a glance for the same reason. The list parser quietly drops any token it cannot read as a number rather than raising an error, so one stray word in a pasted column shrinks your list silently. Checking that the count matches what you pasted is the fastest way to catch it.

Getting the list in cleanly

Separators are commas, semicolons, spaces and new lines, so a copied spreadsheet column pastes straight in. Two things are worth knowing. A thousands separator is a comma, so 1,000 arrives as two separate numbers, 1 and 0 — strip the commas from big figures first. And negatives, decimals and scientific notation are all accepted, so -3.5 and 1e3 read as −3.5 and 1,000.

One average this tool deliberately does not compute is the weighted mean, where each value carries its own importance. Averaging two already-averaged groups is the classic trap: a class of 20 scoring 70% and a class of 30 scoring 80% combine to (20×70 + 30×80) ÷ 50 = 76%, not the 75% you get from averaging 70 and 80. Feed in the individual scores, or weight them yourself before you paste. Standard Deviation Calculator takes the same list and measures how far the values sit from the mean you just computed.

Private and instant

The list never leaves your browser; every statistic is computed locally with no upload and no account.