In Excel: use =SLOPE(known_ys, known_xs) and =INTERCEPT(known_ys, known_xs) — together they give the two coefficients of the best-fit straight line, y = slope × x + intercept.
Syntax
Arguments
| Argument | Description | |
|---|---|---|
known_ys | required | The dependent values — the thing being predicted. |
known_xs | required | The independent values, the same size as known_ys. |
Related functions
Select a cell for the slope and type =SLOPE(.
Select the y values (the outcome) FIRST, then a comma, then the x values.
Repeat in a second cell with =INTERCEPT and the same argument order.
Combine them as intercept + slope × x to predict any new value.
What this does
SLOPE and INTERCEPT return the two numbers that define the least-squares regression line through a set of points. SLOPE is the rate of change — how much y moves per unit of x — and INTERCEPT is where the line crosses at x = 0. Written out they reproduce exactly the trendline equation a chart displays, which makes them the way to use a fitted line in calculations rather than merely look at one. Watch the argument order: the y values come first, which is the reverse of how most people say "x against y". The same idea underpins a lot of everyday Excel work, so the few minutes spent getting it right here pay back across every sheet you build afterwards. Treat it as a pattern, not a one-off, and it stops being something you look up and starts being something you reach for. For “find slope on excel”, the reliable version is a short checking loop, not just the first command that appears to work. Run it on a deliberately small range first, watch how the affected cells change, and only then apply the same setup to the full sheet. When a formula is involved, keep the inputs labelled beside it, reference cells instead of typing values, and apply number formatting only after the result checks out. That is what makes a data step that keeps your analysis trustworthy useful in real work: repeatable, auditable, and not dependent on memory or luck.
A worked example
Units produced in B2:B40 and total cost in C2:C40: =SLOPE(C2:C40, B2:B40) returns the variable cost per unit and =INTERCEPT(C2:C40, B2:B40) the fixed cost. Predicting the cost of 250 units is then =INTERCEPT(...) + SLOPE(...)*250, which is what FORECAST.LINEAR does in a single call. SLOPE and INTERCEPT take a chart trendline out of the picture and put it into the model, where it can drive actual calculations. A practical tip before you scale it up: build it once on a small block of test data, confirm the number against the tool on this page, and only then point it at your real sheet. That one habit catches almost every mistake while it is still cheap to fix, long before a wrong figure reaches a report or a colleague.
In Google Sheets
Everything above works in Google Sheets too. Excel and Sheets share the formula syntax used here; only the surrounding menus are arranged differently. That portability is deliberate — learn it once and it follows you between the two tools and across Windows and Mac. The aim was to get you unstuck fast and leave you a little more capable than a copy-paste would. The answer is at the top, the tool proves it, and the detail above shows why it holds — so the next time a colleague asks, you can answer without reaching for search. The short version of “find slope on excel”: the answer is at the top of this page, the tool proves it on your own numbers, and the sections above explain why it holds so the next variation does not stump you. Excel rewards people who reference cells instead of typing values and who keep inputs separate from formulas, because that is what makes a result you can audit months later. Build it once, deliberately, with the live tool as a check, and you convert a one-off lookup into a reusable skill — which is the whole point of learning the why and not just the what.
Common mistakes
- Reversing the arguments — y comes first in both functions, and swapping them silently returns a different line.
- Extrapolating far beyond the observed x range, where a straight line has no support from the data.
- Fitting a line to plainly curved data; check the scatter plot before trusting either coefficient.
Frequently asked questions
Which argument comes first?
The y values — the thing being predicted. =SLOPE(known_ys, known_xs).
How do I get the trendline equation from a chart into cells?
SLOPE and INTERCEPT return exactly those two coefficients, so you can use the fitted line in formulas instead of reading it off the chart.
How do I predict a value?
=INTERCEPT(ys,xs) + SLOPE(ys,xs)*newX, or the shorter =FORECAST.LINEAR(newX, ys, xs).
Other ways people ask this
People reach this page typing “how to find the slope in excel”, “how do you find slope on excel”, “how to find a slope in excel” and “how to find slope with excel”, among other phrasings; whichever wording you used, the fix above is the one you want.
Why do people search for this in so many different ways?
Because the same task has many names. “how to find the slope in excel”, “how do you find slope on excel”, “how to find a slope in excel” all point at the one operation explained on this page, which is why they all lead here.