💼 4 Free Business Calculators
Business Calculators
Profit margin, revenue, depreciation, and inventory — business tools that turn raw numbers into clear decisions, with verified formulas and worked examples.
All Business Calculators (4)
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Profit Margin — Three Types Explained
Profit margin measures how much of each dollar of revenue a business keeps as profit. There are three levels — gross, operating, and net — each stripping away a different set of costs. Understanding which margin you're calculating matters because each serves a different analytical purpose.
Gross Profit Margin = (Revenue − COGS) ÷ Revenue × 100
Operating Margin = (Revenue − COGS − OpEx) ÷ Revenue × 100
Net Profit Margin = Net Profit ÷ Revenue × 100
Worked example — Revenue: $50,000:
COGS: $32,000
Gross Profit: $50,000 − $32,000 = $18,000
Gross Margin: $18,000 ÷ $50,000 × 100 = 36.0%
Operating Expenses: $8,000
Operating Profit: $18,000 − $8,000 = $10,000
Operating Margin: $10,000 ÷ $50,000 × 100 = 20.0%
Taxes (25%): $10,000 × 0.25 = $2,500
Net Profit: $10,000 − $2,500 = $7,500
Net Margin: $7,500 ÷ $50,000 × 100 = 15.0%
Markup vs Margin — A Critical Difference
Markup and margin look similar but use different denominators — markup uses cost as the base, margin uses selling price. Mixing them up is one of the most common pricing errors in small business.
Markup = (Selling Price − Cost) ÷ Cost × 100
Margin = (Selling Price − Cost) ÷ Selling Price × 100
Example — Cost=$80, Selling Price=$100:
Markup = (100 − 80) ÷ 80 × 100 = 25.0%
Margin = (100 − 80) ÷ 100 × 100 = 20.0%
Converting between them:
Margin from Markup: Margin = Markup ÷ (1 + Markup)
25% markup → 25 ÷ 125 × 100 = 20% margin ✓
Markup from Margin: Markup = Margin ÷ (1 − Margin)
20% margin → 20 ÷ 80 × 100 = 25% markup ✓
📌 Key rule: Margin is always lower than markup for the same product. If a supplier quotes a "40% markup" and you quote customers a "40% margin," you're pricing the same product at two different levels without realizing it. Always clarify which basis is being used. Reference: SBA — Manage Your Business Finances
Depreciation — Straight Line vs Double Declining Balance
Depreciation spreads the cost of a long-term asset over its useful life. Two methods are most common: straight-line (equal amounts each year) and double declining balance (larger amounts early, smaller later). Both start from the same asset cost and salvage value but allocate expense differently.
Straight-Line Depreciation:
Annual Dep = (Cost − Salvage Value) ÷ Useful Life
Example — Cost=$120,000, Salvage=$20,000, Life=5 years:
Annual Dep = ($120,000 − $20,000) ÷ 5 = $20,000/year
Year 1: Dep=$20,000 | Book Value=$100,000
Year 2: Dep=$20,000 | Book Value=$80,000
Year 3: Dep=$20,000 | Book Value=$60,000
Year 4: Dep=$20,000 | Book Value=$40,000
Year 5: Dep=$20,000 | Book Value=$20,000
Double Declining Balance (same asset, rate = 2÷5 = 40%):
Year 1: Dep=$48,000.00 | Book Value=$72,000.00
Year 2: Dep=$28,800.00 | Book Value=$43,200.00
Year 3: Dep=$17,280.00 | Book Value=$25,920.00
Year 4: Dep=$10,368.00 | Book Value=$15,552.00
Year 5: Dep=$6,220.80 | Book Value=$9,331.20
Inventory Turnover and Days in Inventory
Inventory turnover measures how many times a business sells and replaces its stock in a given period. Higher turnover means inventory moves quickly (less storage cost, less obsolescence risk). Days in inventory (also called Days Sales of Inventory) converts turnover into a time measure — how many days, on average, stock sits before being sold.
COGS = Beginning Inventory + Purchases − Ending Inventory
Inventory Turnover = COGS ÷ Average Inventory
Days in Inventory = 365 ÷ Inventory Turnover
Example:
Beginning Inventory: $40,000
Purchases: $95,000
Ending Inventory: $35,000
COGS = $40,000 + $95,000 − $35,000 = $100,000
Average Inventory = ($40,000 + $35,000) ÷ 2 = $37,500
Turnover = $100,000 ÷ $37,500 = 2.67 times/year
Days = 365 ÷ 2.67 = 136.9 days
Revenue Calculation
Revenue (also called gross sales or top-line revenue) is simply units sold multiplied by price per unit. The revenue calculator handles more complex scenarios — multiple product lines, discount effects, and revenue vs net revenue after returns.
Revenue = Units Sold × Price Per Unit
Example:
Units = 1,200 | Price = $45
Revenue = 1,200 × $45 = $54,000
With 10% discount applied:
Discounted Price = $45 × (1 − 0.10) = $40.50
Revenue = 1,200 × $40.50 = $48,600
Revenue impact of discount = $54,000 − $48,600 = $5,400 lost
Percentage revenue drop = $5,400 ÷ $54,000 × 100 = 10%
(A 10% price discount = exactly 10% revenue reduction at same volume)
5 Business Calculation Tips
- A 10% price cut needs more than 10% more sales to maintain profit. If your net margin is 15% and you cut price by 10%, you need to sell roughly 200% more units just to break even on profit — not 10% more. The exact figure depends on your current margin. The lower your margin, the more damaging a price reduction is. Use the profit margin calculator to model the volume needed before discounting.
- Gross margin and net margin tell very different stories. A 36% gross margin looks healthy, but after $8,000 in operating expenses on $50,000 revenue it drops to 20% operating margin, and to 15% net after taxes. Always examine all three levels — a business can have strong gross margins but poor net margins if overhead is high.
- Double declining balance front-loads depreciation tax benefits. In the $120,000 asset example, DDB gives $48,000 in depreciation expense in Year 1 vs $20,000 under straight-line. That extra $28,000 deduction in Year 1 reduces taxable income immediately, which has a real cash value in that year. Businesses with high early-year profits often prefer DDB for assets that lose value quickly (vehicles, electronics).
- Inventory turnover of 2.67 means stock sits for 137 days on average. Industry benchmarks vary widely: grocery retail targets 20–30 turns/year (12–18 days); furniture retail might average 3–4 turns (91–122 days); manufacturing often runs 4–6 turns. Compare your turnover to your industry average — turnover too low means excess capital tied up in stock; too high may mean stockouts and lost sales.
- Revenue and profit are not the same, and confusing them is costly. Revenue is the total amount billed to customers. Profit is what remains after subtracting all costs. A business with $1 million in revenue and $950,000 in costs has a 5% net margin ($50,000 profit) — far less impressive than the revenue number alone suggests. Always check margin alongside revenue when evaluating business performance. Reference: Investopedia — Profit Margin
Frequently Asked Questions — Business Calculators
Gross margin only subtracts cost of goods sold (COGS) from revenue. Net margin subtracts all costs — COGS, operating expenses, interest, and taxes. For a $50,000 revenue business with $32,000 COGS, $8,000 operating expenses, and 25% taxes: gross margin = 36.0%, operating margin = 20.0%, net margin = 15.0%. Each level reveals a different layer of the business's cost structure.
Markup uses cost as the base; margin uses selling price. For a product that costs $80 and sells for $100: markup = (100−80)÷80 × 100 = 25%, margin = (100−80)÷100 × 100 = 20%. The margin is always lower than the markup for the same product. To convert: margin = markup ÷ (1 + markup); markup = margin ÷ (1 − margin). Confusing the two leads to systematic under-pricing.
Annual depreciation = (Asset Cost − Salvage Value) ÷ Useful Life. For a $120,000 asset with $20,000 salvage value and 5-year life: Annual Dep = ($120,000 − $20,000) ÷ 5 = $20,000/year. Book value drops by $20,000 each year: $100,000 after Year 1, $80,000 after Year 2, down to $20,000 (salvage value) at Year 5.
It depends heavily on the industry. Grocery/FMCG: 15–30 turns/year (12–24 days in inventory). Clothing retail: 4–6 turns (60–90 days). Furniture: 3–4 turns (90–120 days). Manufacturing: 4–6 turns (60–90 days). In the worked example (turnover 2.67, days 136.9), stock sits for about 4.5 months — which would be slow for most retail but acceptable for seasonal or specialty goods. Compare to your industry benchmark, not a universal number.
Use double declining balance when the asset loses value quickly in early years (vehicles, computers, machinery) or when you want larger tax deductions early to offset high early-year profits. DDB front-loads depreciation: for a $120,000 asset over 5 years, DDB gives $48,000 in Year 1 vs $20,000 straight-line. In later years, DDB gives less — Year 5 gives only $6,220.80 vs $20,000 straight-line. The total depreciated amount differs because DDB doesn't always reach the salvage value — the depreciation calculator shows both methods side by side.
At the same volume, a 10% price discount reduces revenue by exactly 10%. For 1,200 units at $45: revenue = $54,000. At $40.50 (10% off): revenue = $48,600 — a loss of $5,400. But the profit impact is much larger than 10% because fixed costs don't change. If net margin was 15% ($8,100 profit), the $5,400 revenue loss could eliminate two-thirds of profit. Use the revenue and profit margin calculators together to see the full impact before applying discounts.