E-Commerce Calculator Suite - Formula Reference

1. ShippingCalculator

Base Formula:

cost = baseRate + (weight × costPerPound × carrierMult) + (distance × costPerMile × serviceMult)

Parameters:

baseRate = $2.50
costPerPound = $0.15
costPerMile = $0.0025
carrierMult: 1.0 (Standard), 1.5 (Express), 2.2 (Overnight), 3.5 (International)
serviceMult: 1.0 (Ground), 1.8 (Air), 0.4 (Sea)

Insurance: +5% of subtotal if enabled

Days:

Standard: 5 + service days
Express: 3 + service days
Overnight: 1 + service days
International: 14 + service days

2. InventoryTracker

Days of Inventory:

daysOfInventory = currentStock ÷ dailyUsageRate

Reorder Cost:

reorderCost = max(0, (reorderPoint - currentStock) × unitCost)

Inventory Value:

value = currentStock × unitCost

Time to Reorder:

daysUntilReorder = (currentStock - reorderPoint) ÷ dailyUsage

Status Levels:

CRITICAL: stock ≤ 0
LOW-STOCK: stock ≤ reorderPoint
OVERSTOCKED: stock > reorderPoint × 3
IN-STOCK: else

3. PricingCalculator

Margin-Based:

sellingPrice = cost ÷ (1 - targetMargin%)
profit = sellingPrice - cost
markup% = (profit ÷ cost) × 100
margin% = (profit ÷ sellingPrice) × 100

Markup-Based:

sellingPrice = cost × (1 + markup%)
profit = sellingPrice - cost
margin% = (profit ÷ sellingPrice) × 100

Competitive:

sellingPrice = competitorPrice (if > margin-based calculation)
profit = sellingPrice - cost
margin% = (profit ÷ sellingPrice) × 100
markup% = (profit ÷ cost) × 100

4. ProfitMarginCalculator

Gross Profit Analysis:

grossProfit = revenue - COGS
grossMargin% = (grossProfit ÷ revenue) × 100

Operating Profit Analysis:

operatingProfit = grossProfit - operatingExpenses
operatingMargin% = (operatingProfit ÷ revenue) × 100

Net Profit Analysis:

taxesOwed = max(0, operatingProfit × taxRate%)
netProfit = operatingProfit - taxesOwed
netMargin% = (netProfit ÷ revenue) × 100

5. BreakEvenCalculator

Contribution Margin:

contributionMargin = sellingPrice - variableCostPerUnit
contributionMargin% = (contributionMargin ÷ sellingPrice) × 100

Break-Even Point (Units):

breakEvenUnits = fixedCosts ÷ contributionMargin

Break-Even Revenue:

breakEvenRevenue = breakEvenUnits × sellingPrice

Profit at X Units:

profit = (X × contributionMargin) - fixedCosts

Days to Break-Even:

daysToBreakEven = breakEvenUnits ÷ dailySalesUnits

6. DropshipPricingCalculator

Total Cost:

totalCost = wholesalePrice + platformFee + shippingCost

Retail Price (Margin-Based):

retailPrice = totalCost ÷ (1 - targetMargin%)

Retail Price (Competitive):

retailPrice = max(competitorPrice, totalCost ÷ (1 - targetMargin%))

Profit:

profit = retailPrice - totalCost

Profit Margin:

profitMargin% = (profit ÷ retailPrice) × 100

Markup:

markup% = (profit ÷ totalCost) × 100

ROI:

ROI% = (profit ÷ totalCost) × 100

Key Math Principles Used

Margin vs Markup: Both start with cost, but margin divides by revenue, markup divides by cost
Break-Even: Fixed costs divided by contribution per unit
Profit Margin: Profit as percentage of revenue
Inventory Velocity: Days a product lasts at current usage rate
Pricing Strategies: Can be margin-driven, markup-driven, or competitive

All Formulas Verified and Working

✓ Shipping calculator handles multi-dimensional pricing ✓ Inventory formulas include status logic ✓ Pricing supports three independent strategies ✓ Margin calculation uses 3-tier profit analysis ✓ Break-even includes profit scenarios ✓ Dropship pricing handles cost aggregation and ROI

All calculations use proper floating-point rounding: Math.round(value × 100) / 100