SaaS Unit Economics Waterfall

import matplotlib.pyplot as plt
import numpy as np
from matplotlib.patches import Patch

# Unit economics (monthly $ per customer)
categories = ['Gross\nRevenue', 'Payment\nFees', 'Hosting\nCosts', 'Support\nCosts', 
              'Gross\nMargin', 'CAC\nPayback', 'Retention\nCosts', 'Contribution\nMargin']
values = [0, -8.50, -12.00, -15.50, 0, -18.00, -6.00, 0]

# Calculate through the waterfall
initial = 89.00
running_total = initial
bottoms = []
heights = []
colors = []

for i, (cat, val) in enumerate(zip(categories, values)):
    if cat == 'Gross\nRevenue':
        bottoms.append(0)
        heights.append(initial)
        colors.append('#27D3F5')
    elif cat == 'Gross\nMargin':
        bottoms.append(0)
        heights.append(running_total)
        colors.append('#F5B027')
    elif cat == 'Contribution\nMargin':
        bottoms.append(0)
        heights.append(running_total)
        colors.append('#6CF527')
    elif val < 0:
        bottoms.append(running_total + val)
        heights.append(abs(val))
        colors.append('#F5276C')
        running_total += val

# Create figure - light theme
fig, ax = plt.subplots(figsize=(14, 8), facecolor='#ffffff')
ax.set_facecolor('#ffffff')

x = np.arange(len(categories))
bars = ax.bar(x, heights, bottom=bottoms, color=colors, width=0.65, edgecolor='#e5e7eb', linewidth=1)

# Add value labels
labels = [89.00, 8.50, 12.00, 15.50, 53.00, 18.00, 6.00, 29.00]
for i, (bar, label, bot, height) in enumerate(zip(bars, labels, bottoms, heights)):
    y_pos = bot + height / 2
    if categories[i] in ['Gross\nRevenue', 'Gross\nMargin', 'Contribution\nMargin']:
        text = f"${label:.2f}"
        color = 'white' if height > 35 else '#374151'
    else:
        text = f"-${label:.2f}"
        color = 'white'
    ax.text(bar.get_x() + bar.get_width()/2, y_pos, text, 
            ha='center', va='center', fontsize=10, fontweight='bold', color=color)

# Styling
ax.set_xlim(-0.6, len(categories) - 0.4)
ax.set_ylim(0, initial * 1.1)
ax.set_xticks(x)
ax.set_xticklabels(categories, fontsize=9, color='#374151')
ax.set_ylabel('Monthly $ per Customer', fontsize=12, color='#374151', fontweight='500')
ax.set_title('SaaS Unit Economics: Revenue to Contribution Margin', fontsize=16, color='#111827', fontweight='bold', pad=20)

ax.tick_params(axis='y', colors='#374151', labelsize=10)
ax.yaxis.grid(True, linestyle='--', alpha=0.4, color='#e5e7eb')
ax.set_axisbelow(True)

for spine in ax.spines.values():
    spine.set_color('#d1d5db')

# Margin percentages
gross_margin_pct = 53.00 / 89.00 * 100
contrib_margin_pct = 29.00 / 89.00 * 100
ax.annotate(f'Gross Margin: {gross_margin_pct:.1f}% | Contribution Margin: {contrib_margin_pct:.1f}%', 
            xy=(0.5, 0.95), xycoords='axes fraction',
            fontsize=11, color='#374151', ha='center', fontweight='bold',
            bbox=dict(boxstyle='round,pad=0.4', facecolor='#f3f4f6', edgecolor='#d1d5db'))

# Legend outside plot
legend_elements = [
    Patch(facecolor='#27D3F5', label='Revenue'),
    Patch(facecolor='#F5276C', label='Costs'),
    Patch(facecolor='#F5B027', label='Gross Margin'),
    Patch(facecolor='#6CF527', label='Contribution Margin')
]
ax.legend(handles=legend_elements, loc='upper left', bbox_to_anchor=(0, -0.1), 
          ncol=4, fontsize=9, facecolor='white', edgecolor='#d1d5db', labelcolor='#374151')

plt.tight_layout()
plt.subplots_adjust(bottom=0.15)
plt.show()