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Small Business Finance 101: Essential Calculations + Formulas

Master the numbers that keep your business alive. Pricing formulas, profit margins, cash flow, and break-even calculations—explained simply with real examples.

Tiny Tools Team8 min read

We threw a party when Tiny Tools hit its first $10,000 month. Champagne, high-fives, the works. Then we did the math and realized we'd netted $400 after expenses. That party was expensive.

Revenue is applause. Profit is whether you can pay rent after the show.

Running a small business taught us finance the hard way—pricing mistakes that left money on the table, cash flow surprises that nearly sank us, and the painful lesson that a business can be "successful" and still run out of money.

This guide covers the financial fundamentals every small business owner needs. Not accounting theory—the actual numbers we wish we'd understood from day one, explained the way we had to learn them: through expensive mistakes you don't have to repeat.

Essential Financial Concepts

Revenue vs. Profit

Revenue: Total money coming in Profit: What's left after expenses

A business with $100,000 revenue and $95,000 expenses has $5,000 profit. Revenue sounds impressive; profit pays bills.

We initially celebrated revenue milestones without tracking where the money went. Learning to focus on profit changed everything.

Gross vs. Net Profit

Gross profit: Revenue minus direct costs (cost of goods sold) Net profit: Revenue minus all costs (including overhead)

Example:

  • Revenue: $100,000
  • Cost of goods: $40,000
  • Gross profit: $60,000 (60% gross margin)
  • Operating expenses: $35,000
  • Net profit: $25,000 (25% net margin)

Fixed vs. Variable Costs

Fixed costs: Don't change with sales volume

  • Rent, salaries, insurance, subscriptions

Variable costs: Change with sales volume

  • Materials, transaction fees, packaging, shipping

Understanding this distinction is crucial for pricing and scaling decisions.

Pricing Your Products/Services

Cost-Plus Pricing

Formula: Cost + Markup = Price

  1. Calculate total cost to deliver
  2. Add desired profit margin
  3. Result is minimum price

Example:

  • Cost to deliver service: $50
  • Desired 40% margin
  • Price: $50 ÷ (1 - 0.40) = $83.33

Use our Percentage Calculator for margin calculations.

Value-Based Pricing

Price based on customer value, not your costs:

  • What problem does it solve?
  • What's the alternative cost for customers?
  • How much is the outcome worth?

Example: A tool saving 10 hours of work monthly is worth far more than its development cost if those hours are valuable.

We underpriced initially based on costs alone. Value-based thinking helped us price appropriately.

Common Pricing Mistakes

Too low:

  • Doesn't cover true costs
  • Attracts price-sensitive customers
  • Hard to raise later
  • Signals low quality

Too high:

  • Limits market
  • Requires more sales effort
  • May not match perceived value

Not testing:

  • Guessing instead of experimenting
  • Assuming you know what customers will pay

Pricing Calculations

Markup on cost: Price = Cost × (1 + Markup%)

Margin from price: Margin = (Price - Cost) ÷ Price × 100

Price from desired margin: Price = Cost ÷ (1 - Desired Margin%)

Quick conversions:

MarkupEquivalent Margin
25%20%
33%25%
50%33%
100%50%

Understanding Margins

Why Margins Matter

Margin determines how much of each sale becomes profit. Low margins mean you need high volume; high margins allow lower volume.

Low margin business: 10% margin means $100 sale = $10 toward overhead/profit High margin business: 60% margin means $100 sale = $60 toward overhead/profit

Calculating Your Margins

Gross margin: (Revenue - Cost of Goods) ÷ Revenue × 100

Net margin: Net Profit ÷ Revenue × 100

Target margins vary by industry:

  • Retail: 25-50% gross margin
  • Services: 50-80% gross margin
  • Software: 70-90% gross margin

Improving Margins

Increase revenue:

  • Raise prices
  • Upsell/cross-sell
  • Add premium tiers

Decrease costs:

  • Negotiate with suppliers
  • Improve efficiency
  • Reduce waste
  • Automate where possible

We improved margins more by raising prices than by cutting costs. Cutting costs has limits; value creation doesn't.

Cash Flow Management

Cash Flow vs. Profit

You can be profitable and still run out of cash:

  • Customers pay late
  • Expenses come before revenue
  • Growth requires investment

Cash is oxygen. Profit means nothing if you can't pay this month's bills.

The Cash Flow Cycle

  1. Spend money on costs
  2. Deliver product/service
  3. Invoice customer
  4. Wait for payment
  5. Receive cash

The gap between steps 1 and 5 is your cash cycle. The longer it is, the more working capital you need.

Improving Cash Flow

Speed up inflows:

  • Request deposits upfront
  • Invoice immediately upon delivery
  • Offer incentives for early payment
  • Accept multiple payment methods
  • Follow up on late payments promptly

Slow down outflows:

  • Negotiate longer payment terms with suppliers
  • Avoid prepaying unless discounted
  • Time large purchases carefully
  • Maintain cash reserves

Cash Reserve Target

Rule of thumb: 3-6 months of operating expenses in reserve.

This protects against:

  • Seasonal fluctuations
  • Unexpected expenses
  • Client payment delays
  • Economic downturns

We almost ran out of cash during a slow month despite being profitable on paper. Now we maintain reserves religiously.

Break-Even Analysis

What Is Break-Even?

The point where revenue equals costs—no profit, no loss.

Formula: Break-even units = Fixed Costs ÷ (Price - Variable Cost per Unit)

Example:

  • Fixed costs: $5,000/month
  • Price: $100
  • Variable cost: $40
  • Contribution margin: $60
  • Break-even: $5,000 ÷ $60 = 84 units

You need to sell 84 units to cover costs. Every unit after that is profit.

Why It Matters

Break-even tells you:

  • Minimum sales needed to survive
  • Impact of price changes
  • Effect of cost changes
  • Risk level of the business

Break-Even for Services

For service businesses:

Break-even hours: Fixed Costs ÷ (Hourly Rate - Variable Cost per Hour)

Example:

  • Monthly fixed costs: $3,000
  • Hourly rate: $100
  • Variable costs per hour: $10
  • Break-even: $3,000 ÷ $90 = 34 billable hours/month

Financial Tracking

What to Track

Minimum:

  • Revenue by source
  • Major expense categories
  • Profit margin
  • Cash position

Better:

  • Customer acquisition cost
  • Customer lifetime value
  • Accounts receivable aging
  • Monthly recurring revenue (if applicable)

Tracking Frequency

Weekly:

  • Cash position
  • Outstanding invoices
  • Upcoming expenses

Monthly:

  • Profit and loss review
  • Margin calculations
  • Budget vs. actual

Quarterly:

  • Trend analysis
  • Pricing review
  • Strategic planning

Simple Tracking Methods

You don't need complex software:

  • Spreadsheet for basics
  • Accounting software as you grow (QuickBooks, Wave, FreshBooks)
  • Separate business bank account (essential)

Business Growth Math

Customer Acquisition Cost (CAC)

Formula: Marketing & Sales Spend ÷ New Customers Acquired

Example: $2,000 marketing spend ÷ 40 new customers = $50 CAC

Customer Lifetime Value (LTV)

Simple formula: Average Purchase × Purchase Frequency × Customer Lifespan

Example: $100 average × 4 times/year × 3 years = $1,200 LTV

LTV to CAC Ratio

Healthy ratio: LTV > 3× CAC

If you spend $50 to acquire a customer worth $1,200, you're in good shape (24:1 ratio).

If LTV barely exceeds CAC, you have a problem.

Growth Investment

Use our Compound Interest Calculator to model reinvestment scenarios:

  • What if you reinvest 50% of profits?
  • How does growth compound over years?
  • What investment level is sustainable?

Common Financial Mistakes

Ignoring Taxes

Revenue isn't yours to spend. Set aside for taxes immediately.

Rule of thumb: 25-30% of profit for taxes (varies by structure and location).

We learned this painfully with a surprise tax bill. Now we transfer tax estimates monthly.

Mixing Personal and Business

Separate accounts for:

  • Legal protection
  • Tax simplicity
  • Financial clarity
  • Professional appearance

Not Tracking Time

For service businesses, untracked time is leaked profit:

  • Track all time, even "small" tasks
  • Know your actual hourly revenue
  • Identify unprofitable clients/projects

Pricing Based on Competition

Competitors may have:

  • Different cost structures
  • Different value propositions
  • Unsustainable pricing
  • Different markets

Price based on your costs and value, informed by (not dictated by) competition.

Quick Financial Formulas

MetricFormula
Gross Margin(Revenue - COGS) ÷ Revenue
Net MarginNet Profit ÷ Revenue
Break-even UnitsFixed Costs ÷ (Price - Variable Cost)
Markup(Price - Cost) ÷ Cost
CACMarketing Spend ÷ New Customers
LTVAvg Purchase × Frequency × Lifespan

Use our Percentage Calculator for quick margin and markup calculations.

Conclusion

You can ignore the numbers, but the numbers won't ignore you. Every failed business we've seen (including our early attempts) missed the signals hiding in their margins, cash flow, or break-even math.

Cash is oxygen. Profit is health. Don't confuse them.

A business can be "profitable" on paper and still suffocate from cash flow problems. A business can have impressive revenue and still lose money. The numbers tell you the truth—but only if you're listening.

Start simple: track revenue, expenses, and cash position weekly. Know your margins. Understand your break-even. Use our Percentage Calculator for margin math and our Compound Interest Calculator to model growth scenarios.

The numbers aren't the enemy. They're the early warning system that keeps you in business.


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Content crafted by the Tiny Tools team with AI assistance.

Tiny Tools Team

Building free, privacy-focused tools for everyday tasks

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