Bar Chart with Error Bars — Matplotlib

A bar chart with error bars displays categorical data as rectangular bars with vertical (or horizontal) lines extending from each bar to indicate uncertainty or variability. Error bars typically represent standard deviation, standard error, confidence intervals, or min/max ranges. This visualization is essential for comparing group means while communicating the reliability and precision of each measurement.

Bar Chart with Error Bars rendered with Matplotlib

Python source (Matplotlib)

""" anyplot.ai
bar-error: Bar Chart with Error Bars
Library: matplotlib 3.10.9 | Python 3.13.13
Quality: 86/100 | Updated: 2026-05-10
"""

import os

import matplotlib.pyplot as plt
import numpy as np


# Theme tokens
THEME = os.getenv("ANYPLOT_THEME", "light")
PAGE_BG = "#FAF8F1" if THEME == "light" else "#1A1A17"
ELEVATED_BG = "#FFFDF6" if THEME == "light" else "#242420"
INK = "#1A1A17" if THEME == "light" else "#F0EFE8"
INK_SOFT = "#4A4A44" if THEME == "light" else "#B8B7B0"
BRAND = "#009E73"  # Okabe-Ito position 1

# Data: A/B test results comparing feature variants with confidence intervals
np.random.seed(42)
categories = ["Control", "Variant A", "Variant B", "Variant C", "Variant D"]
values = [12.3, 15.8, 14.2, 18.5, 11.7]
errors = [1.2, 2.1, 1.5, 2.8, 1.0]

# Plot
fig, ax = plt.subplots(figsize=(16, 9), facecolor=PAGE_BG)
ax.set_facecolor(PAGE_BG)

x = np.arange(len(categories))
bar_width = 0.6

bars = ax.bar(x, values, bar_width, color=BRAND, edgecolor=INK_SOFT, linewidth=1.5)
ax.errorbar(x, values, yerr=errors, fmt="none", ecolor=INK_SOFT, elinewidth=2.5, capsize=8, capthick=2)

# Labels and styling
ax.set_xlabel("Test Group", fontsize=20, color=INK)
ax.set_ylabel("Conversion Rate (%)", fontsize=20, color=INK)
ax.set_title("bar-error · matplotlib · anyplot.ai", fontsize=24, fontweight="medium", color=INK)
ax.set_xticks(x)
ax.set_xticklabels(categories, fontsize=16, color=INK_SOFT)
ax.tick_params(axis="y", labelsize=16, colors=INK_SOFT)

# Spines
ax.spines["top"].set_visible(False)
ax.spines["right"].set_visible(False)
for s in ("left", "bottom"):
    ax.spines[s].set_color(INK_SOFT)

# Grid
ax.yaxis.grid(True, alpha=0.15, linewidth=0.8, color=INK)

# Annotation
ax.annotate(
    "Error bars: 95% CI",
    xy=(0.98, 0.02),
    xycoords="axes fraction",
    fontsize=14,
    ha="right",
    va="bottom",
    color=INK_SOFT,
    bbox={
        "boxstyle": "round,pad=0.5",
        "facecolor": ELEVATED_BG,
        "edgecolor": INK_SOFT,
        "alpha": 0.9,
        "linewidth": 1,
    },
)

ax.set_ylim(0, max(values) * 1.3)

plt.tight_layout()
plt.savefig(f"plot-{THEME}.png", dpi=300, bbox_inches="tight", facecolor=PAGE_BG)

Part of Bar Chart with Error Bars on anyplot.ai.

Bar Chart with Error Bars — Matplotlib

Python source (Matplotlib)

Other implementations