Regression line plot

Seaborn basics

2 min read

Published Oct 7 2025, updated Aug 17 2026

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seaborn.regplot() plots data points (scatter) along with a regression line (best-fit line).
It is an axes-level function (draws on a single subplot).

It’s mainly used to visualise the relationship between two numeric variables, showing both the trend (linear regression) and the data spread.

Syntax:

sns.regplot(    data=None,    *,    x=None,    y=None,    x_estimator=None,    x_bins=None,    x_ci='ci',    scatter=True,    fit_reg=True,    order=1,    robust=False,    logx=False,    ci=95,    n_boot=1000,    seed=None,    line_kws=None,    scatter_kws=None,    color=None,    marker='o',    ax=None,    **kwargs)

Parameters:

data = DataFrame containing the data
x, y = Numeric variables for regression
scatter = If True, shows scatter points
fit_reg = If True, draws regression line
order = Degree of polynomial (1 = linear)
robust = Use robust regression (less sensitive to outliers)
logx = If True, log-transform the x-axis
ci = Confidence interval around regression line (in %)
line_kws = Dictionary of keyword args for the line (e.g., colour, linestyle)
scatter_kws = Dictionary of keyword args for scatter points
color = Base colour for both scatter and line
ax = Axis to plot on (for subplot use)

Basic example

import seaborn as snsimport matplotlib.pyplot as plttips = sns.load_dataset("tips")sns.regplot(data=tips, x="total_bill", y="tip")plt.show()

Plots a scatterplot with a best-fit linear regression line. The shaded area shows the 95% confidence interval.

Turn off scatter or line

Line Only:

import seaborn as snsimport matplotlib.pyplot as plttips = sns.load_dataset("tips")sns.regplot(data=tips, x="total_bill", y="tip", scatter=False)plt.show()

Shows only the regression line.

Scatter Only:

import seaborn as snsimport matplotlib.pyplot as plttips = sns.load_dataset("tips")sns.regplot(data=tips, x="total_bill", y="tip", fit_reg=False)plt.show()

Shows only the scatter points (same as sns.scatterplot()).

Change line appearance

import seaborn as snsimport matplotlib.pyplot as plttips = sns.load_dataset("tips")sns.regplot(    data=tips,    x="total_bill",    y="tip",    line_kws={"color": "red", "linestyle": "--", "linewidth": 2})plt.show()

Customises line colour, style, and width.

Add scatter customisation

import seaborn as snsimport matplotlib.pyplot as plttips = sns.load_dataset("tips")sns.regplot(    data=tips,    x="total_bill",    y="tip",    scatter_kws={"s": 80, "alpha": 0.6, "color": "green"})plt.show()

Adjusts point size (s), transparency (alpha), and colour.

seaborn reg plot scatter customise example

Polynomial regression (nonlinear)

import seaborn as snsimport matplotlib.pyplot as plttips = sns.load_dataset("tips")sns.regplot(data=tips, x="total_bill", y="tip", order=2, color="purple")plt.show()

Fits a 2nd-degree polynomial (curve instead of straight line). You can use higher orders (e.g., order=3) for more curvature.

Robust regression

import seaborn as snsimport matplotlib.pyplot as plttips = sns.load_dataset("tips")sns.regplot(data=tips, x="total_bill", y="tip", robust=True)plt.show()

Uses a robust estimator to reduce the effect of outliers on the regression line.

Logarithmic x-axis

import seaborn as snsimport matplotlib.pyplot as plttips = sns.load_dataset("tips")sns.regplot(data=tips, x="total_bill", y="tip", logx=True)plt.show()

Applies a log transformation to the x-axis — useful for skewed data.

Change confidence interval

import seaborn as snsimport matplotlib.pyplot as plttips = sns.load_dataset("tips")sns.regplot(data=tips, x="total_bill", y="tip", ci=68)plt.show()

Shows a 68% confidence interval instead of the default 95%. Set ci=None to remove the shaded band completely.

Binned regression (x_bins)

import seaborn as snsimport matplotlib.pyplot as plttips = sns.load_dataset("tips")sns.regplot(data=tips, x="total_bill", y="tip", x_bins=10)plt.show()

Groups data along the x-axis into bins, showing average y-values for each bin. Useful for very large datasets or when data are not evenly distributed.

Weighted regression (x_estimator)

import seaborn as snsimport matplotlib.pyplot as pltimport numpy as nptips = sns.load_dataset("tips")sns.regplot(data=tips, x="total_bill", y="tip", x_estimator=np.mean)plt.show()

Aggregates y values within x bins (using mean, median, etc.) before fitting the line.

Customise colors and markers

import seaborn as snsimport matplotlib.pyplot as plttips = sns.load_dataset("tips")sns.regplot(    data=tips,    x="total_bill",    y="tip",    color="teal",    marker="x",    line_kws={"color": "orange"})plt.show()

Marker and line customised separately.

Combine with other plots

Example — regression line on top of a histogram of x:

import seaborn as snsimport matplotlib.pyplot as plttips = sns.load_dataset("tips")sns.histplot(data=tips, x="total_bill", bins=20, color="lightgray")sns.regplot(data=tips, x="total_bill", y="tip", scatter=False, color="red")plt.show()

Regression line overlays a histogram background.