Sankey Diagrams: The Ultimate Way to Visualize Your Money Flow
- Alper Musaoglu
- Dec 21, 2025
- 8 min read
See exactly where your money comes from and where it goes at a single glance.
You've downloaded your bank statements. You've categorized your transactions.
You've got months of financial data sitting in spreadsheets. But when someone asks, "Where does your money actually go?"—can you answer confidently?
Most people can't.
That's because raw numbers, no matter how organized, don't tell a story. They don't show you the flow of your financial life. They don't reveal how your paycheck splits into rent, groceries, subscriptions, and savings. They don't make the invisible visible.
Sankey diagrams do.
What is a Sankey Diagram?
A Sankey diagram is a type of flow visualization where the width of each arrow or stream is proportional to the quantity it represents. Money flows from left to right (or top to bottom), splitting and merging as it moves through your financial life.
Think of it like a river system. Your income is the source, a wide stream at the start. As money flows downstream, it branches into smaller tributaries: housing, food, transportation, entertainment, savings. Some streams are wide (your rent payment), others are thin (that streaming subscription you forgot about). By the end, you see exactly how your financial river disperses.
The concept dates back to 1898, when Captain Matthew Sankey created a diagram showing energy efficiency in a steam engine. Today, the same visualization technique has been called "the best statistical graphic ever drawn" when applied to Napoleon's march to Russia by Charles Minard.
This powerful visualisation method is now revolutionising personal finance.
Why Sankey Diagrams Work for Financial Data
1. They Show Proportions Instantly
When you look at a pie chart of your expenses, you see percentages. When you look at a bar chart, you see comparisons. But when you look at a Sankey diagram, you see scale.
A thick stream flowing to "Housing" immediately communicates that this is where most of your money goes, no legend required, no mental math needed. Your brain processes the visual weight before you even read the labels.
2. They Reveal the Complete Picture
Unlike other charts that show snapshots, Sankey diagrams show the entire journey. You see:
Where money comes from (salary, side income, investments)
How it pools together (total income)
Where it splits (fixed expenses, variable spending, savings)
The final destinations (specific merchants, categories, accounts)
This end-to-end visibility is something no other chart type provides as elegantly.
3. They Make Hidden Patterns Obvious
When your expenses are listed in a spreadsheet, it's easy to overlook that you're spending $400/month across six different subscription services. But in a Sankey diagram, all those thin streams flowing to "Subscriptions" combine into a surprisingly thick branch, immediately visible, impossible to ignore.
4. They're Intuitive
You don't need a finance degree to read a Sankey diagram. The metaphor of flowing water or energy is universally understood. Wide = more money. Narrow = less money. Flow direction = where it's going. That's it.
The Psychology of Seeing Your Money Flow
There's a reason the personal finance community on Reddit has embraced Sankey diagrams. Seeing your financial life visualized this way creates an emotional response that spreadsheets simply can't match.
When you see a thick stream of money flowing toward "Dining Out" that's nearly as wide as your "Savings" stream, something clicks. The abstract becomes concrete. The numbers become real.
This visual impact drives behavioural change in ways that budget apps with endless pie charts have failed to achieve. Research in behavioral economics shows that visualization creates stronger emotional connections to financial goals—and emotion drives action.
What Financial Insights Can Sankey Diagrams Reveal?
Income Diversity (or Lack Thereof)
A Sankey diagram instantly shows if you're relying on a single income source (one thick stream) or if you've built multiple income streams (several tributaries feeding into your total). For freelancers and small business owners, this visualization can be eye-opening.
The True Cost of Categories
When you categorize transactions, you might label things as "Shopping" or "Food." But a Sankey diagram shows how these categories stack up against each other and against your total income. Suddenly, "Shopping" isn't just a category—it's 15% of everything you earned that month.
Savings Rate Visualization
Financial independence communities obsess over savings rate for good reason. A Sankey diagram makes your savings rate visceral. When the stream flowing to "Savings & Investments" is thinner than the stream flowing to "Entertainment," no explanation is needed.
Expense Hierarchies
Most budgets have categories, but Sankey diagrams can show multiple levels:
Income → Fixed Expenses → Housing → Rent
→ Utilities
→ Insurance
→ Variable Expenses → Food → Groceries
→ Restaurants
→ Coffee Shops
→ Savings → Emergency Fund
→ Retirement
→ Investment AccountThis hierarchical view reveals where money goes at every level of detail.
Recurring vs. One-Time Expenses
When you visualize multiple months, patterns emerge. The steady streams (rent, subscriptions, utilities) versus the irregular ones (travel, medical, gifts) tell different stories about your financial obligations.
Who Benefits Most from Sankey Financial Visualization?
Individuals Tracking Personal Finances
If you've ever wondered "where does all my money go?" a Sankey diagram answers that question more clearly than any budget app dashboard. It's particularly powerful for:
Identifying spending leaks
Visualizing progress toward savings goals
Understanding the true impact of lifestyle inflation
Motivating financial behavior change
Freelancers and Self-Employed
When income comes from multiple clients and expenses mix business with personal, a Sankey diagram cuts through the chaos. You can visualize:
Which clients contribute most to your income
How business expenses compare to personal
Where to focus growth efforts
Tax-deductible expense categories at a glance
Small Business Owners
Cash flow is the lifeblood of small business. Sankey diagrams transform complex P&L statements into intuitive visuals showing:
Revenue streams by product or service
Cost of goods sold vs. operating expenses
Where profit margins are strongest
How money flows from revenue to net income
Accountants and Bookkeepers
When explaining financial situations to clients, a Sankey diagram communicates in seconds what spreadsheets take minutes to explain. It's a powerful tool for:
Client presentations
Financial health assessments
Identifying areas for cost reduction
Visualizing budget vs. actual spending
Couples Managing Joint Finances
Money conversations are easier with visualization. When both partners can see the same flow diagram, discussions shift from accusations to observations. "I see that dining out is our third-largest expense—should we talk about that?" is more productive than arguing over receipts.
How to Analyze Your Finances Using Sankey Diagrams
Step 1: Gather Your Data
Before you can visualize, you need clean, categorized transaction data. This means:
Bank statement transactions with dates and amounts
Categorized expenses (housing, food, transportation, etc.)
Income sources identified
A time period selected (monthly works best for most people)
Step 2: Define Your Flow Structure
Decide how you want money to flow through your diagram:
Simple Structure:
Income → Expenses
→ SavingsDetailed Structure:
Salary → Total Income → Fixed Expenses → [specific categories]
Side Income ↗ → Variable Expenses → [specific categories]
→ Savings → [specific accounts]Step 3: Calculate the Flows
For each connection in your diagram, you need the dollar amount:
Total income: $5,000
Income → Fixed Expenses: $2,500
Income → Variable Expenses: $1,500
Income → Savings: $1,000
Step 4: Generate Your Visualization
This is where the magic happens. Your categorized data transforms into flowing streams that reveal your financial story.
Step 5: Analyze and Act
With your Sankey diagram in front of you, ask:
Which streams are wider than expected?
Which streams should be wider (like savings)?
Are there streams you didn't realize existed?
How does this month compare to last month?
Introducing Sankey Diagrams in Senki
We built Senki to turn the chaos of bank statements into financial clarity. And now, we're taking that clarity to the next level with Sankey diagram visualization.
How It Works
Upload your bank statements: PDF from any bank, any format
AI categorizes your transactions: automatically, accurately
View your Sankey diagram: see your money flow instantly
No manual data entry. No spreadsheet formulas. No learning curve for complex visualization tools.
What You'll See
Your Senki Sankey diagram shows:
Income Sources
Salary and wages
Side income and freelance
Investment returns
Other income
Expense Categories
Housing (rent, mortgage, utilities)
Transportation (car, gas, transit)
Food (groceries, restaurants, delivery)
Shopping (clothing, electronics, household)
Entertainment (subscriptions, events, hobbies)
Healthcare (insurance, medical, pharmacy)
And more...
Savings & Investments
Bank transfers to savings
Investment contributions
Debt payments
Why Senki's Approach is Different
Most Sankey diagram tools require you to manually input data. You have to:
Export transactions from your bank
Clean up the data in Excel
Categorize every transaction manually
Format data for the visualization tool
Generate the diagram
With Senki, you skip all of that. Upload your statement, and the AI handles categorization. Your Sankey diagram generates automatically.
From PDF to visualization in under 30 seconds.
Real-World Example: What a Sankey Diagram Reveals
Let's say you upload three months of bank statements to Senki. Your Sankey diagram might reveal:
The Obvious:
Rent is your biggest expense (you knew that)
Groceries cost about what you expected
The Surprising:
"Small" subscriptions add up to $287/month across 12 services
You spent more on food delivery than groceries last month
Your "miscellaneous" category is actually 8% of your income
The Actionable:
Canceling 4 unused subscriptions would save $89/month
Cooking more would shift $200 from "Dining" to "Groceries" (and savings)
Your savings rate is 12%—you wanted it to be 20%
This is the power of visualization. Not just seeing numbers, but seeing relationships between numbers.
Best Practices for Financial Sankey Analysis
1. Start with Monthly Views
Annual Sankey diagrams can be overwhelming. Start with a single month to understand the baseline, then expand to quarterly or annual views for trend analysis.
2. Use Consistent Categories
If "Food" includes groceries one month and excludes them the next, your diagrams won't be comparable. Consistent categorization is key—which is why AI-powered auto-categorization matters.
3. Include All Income Sources
Don't just visualize expenses. Include all income streams so you can see the complete picture from source to destination.
4. Compare Periods
The real insights come from comparing Sankey diagrams across time. How has your money flow changed since you got a raise? Since you moved? Since you started tracking?
5. Share and Discuss
Financial visualization becomes more powerful when shared. Discuss with partners, financial advisors, or accountability partners. The visual format makes these conversations more productive.
The Future of Financial Visualization
We're in the early days of applying data visualization to personal finance. For too long, financial tools have given us tables and pie charts—useful, but limited.
Sankey diagrams represent a shift toward visualizations that match how we actually think about money: as something that flows, splits, and moves through our lives.
At Senki, we believe that understanding your finances shouldn't require a finance degree or hours of spreadsheet work. It should be as simple as uploading a document and seeing your story unfold.
Start Seeing Your Money Flow Today
Your bank statements contain the complete story of your financial life. Every transaction, every pattern, every opportunity for improvement, it's all there, hidden in rows of data.
Sankey diagrams bring that story to life.
Ready to see where your money really goes?
Upload your bank statement to Senki and get your personalized Sankey diagram in seconds. No manual categorization. No spreadsheet gymnastics. Just clear, beautiful visualization of your financial flow.
Because understanding your money shouldn't be harder than earning it.
Try Senki Free. Upload your first bank statement and see your money flow visualized instantly.
