MATHEMATICS · INTERACTIVE TOOL

Slope Calculator

Two points in, everything out — slope, angle, percentage grade, intercepts and the full line equation, with step-by-step working and an interactive graph.

FREE — NO SIGN-UP · RUNS ENTIRELY IN YOUR BROWSER
SLOPE CALCULATOR

Enter your values

Point 1
Point 2
TRY —

WAITING FOR INPUT — RESULTS UPDATE AS YOU TYPE

RESULT
SLOPE m
—
—
Enter values to begin — results update as you type.
Slope–intercept—
Standard form—
Point–slope—
Angle—
Grade—rise per 100 of run
y-Intercept—where x = 0
x-Intercept—where y = 0
Perpendicular—slope · −1/m
Direction—reading left to right
Distance—between the two points
Midpoint—between the two points

DRAG TO PAN · SCROLL OR PINCH TO ZOOM · HOVER FOR COORDINATES

HOW TO USE

Four steps. Zero friction.

01

Choose a mode

Two points finds the slope between them. Slope & point builds the line from m and one point. Line equation converts Ax + By = C into slope and intercepts.

02

Enter your values

Plain numbers, negatives, decimals like 0.75 and fractions like 3/4 all work. Everything recalculates live as you type — no calculate button needed.

03

Read the results

Slope, angle, percentage grade, both intercepts, perpendicular slope, distance and midpoint — plus the line written in slope-intercept, standard and point-slope form.

04

Play with the graph

Drag to pan, scroll or pinch to zoom, toggle the rise/run triangle — then copy the full step-by-step solution wherever you need it with one click.

THE MATH

Rise over run, formalised.

m = y₂ − y₁x₂ − x₁ = Δy = riseΔx = run

Slope is the ratio of vertical change to horizontal change between two points on a line — rise over run. Subtract the y-coordinates to get the rise Δy, subtract the x-coordinates to get the run Δx, and divide. The steeper the line, the bigger the magnitude; the sign tells you which way it leans. Two facts worth memorising: parallel lines always share the same slope, and perpendicular slopes multiply to −1.

Positive

m > 0

Rises left to right. Example: y = 2x has slope 2.

Negative

m < 0

Falls left to right. Example: y = −x + 3 has slope −1.

Zero

m = 0

Perfectly horizontal. Example: y = 5 has slope 0.

Undefined

run = 0

Perfectly vertical. Example: x = 4 — division by zero.

FAQ

Slope, decoded.

The questions people actually ask about slope — answered in plain language.

How do I calculate the slope between two points?
Use the slope formula: m = (y₂ − y₁) / (x₂ − x₁). Subtract the y-coordinates (that's the rise), subtract the x-coordinates (that's the run), then divide. For example, with points (2, 3) and (5, 11): m = (11 − 3) / (5 − 2) = 8/3 ≈ 2.667. The calculator above does this instantly — and shows every step.
What does the slope value actually mean?
Slope measures steepness and direction. A slope of 2 means the line climbs 2 units for every 1 unit you move right. A negative slope falls to the right, zero is perfectly flat, and an undefined slope means the line is vertical.
When is a slope undefined?
When the two points have the same x-coordinate. The run Δx = x₂ − x₁ becomes zero, and dividing by zero is undefined. The line is vertical (x = constant) with an inclination angle of exactly 90°.
What is the slope of a horizontal line?
Zero. The rise Δy = 0, so m = 0/run = 0. Every point on a horizontal line has the same y-value, so its equation is simply y = b.
How do I convert a slope to an angle or a percentage grade?
Angle: θ = arctan(m). A slope of 1 is a 45° angle; a slope of 0.5 is about 26.57°. Percentage grade (used for roads and ramps): grade = m × 100. A 0.25 slope is a 25% grade — it rises 25 units per 100 units of run.
What are the three forms of a line equation?
Slope-intercept: y = mx + b — fastest for reading m and b. Point-slope: y − y₁ = m(x − x₁) — best when you know one point and the slope. Standard: Ax + By = C — best for intercepts and exact integer arithmetic. All three describe the same line; this calculator shows all of them.
How do I find a parallel or perpendicular slope?
Parallel lines share the same slope: m₂ = m₁. Perpendicular lines (at 90° to each other) have slopes that multiply to −1: m₂ = −1/m₁ — flip the fraction and change the sign. So a line perpendicular to m = 2 has slope −1/2.
Does the order of my two points matter?
No. (y₂ − y₁)/(x₂ − x₁) and (y₁ − y₂)/(x₁ − x₂) give the same slope — the sign flips in both numerator and denominator and cancels. Just be consistent: don't mix the points up mid-calculation.