Ecommerce Calculators
Run your numbers before you run your ads. Our free ecommerce calculators cover Amazon FBA fees, profit margins, ROAS, AOV, and everything else online sellers need to make profitable decisions.
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Amazon & Marketplace
FBA fees, Amazon profit, referral fees, and break-even ACOS
Store Performance
ROAS, AOV, conversion rate, and revenue projections
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Ecommerce Glossary — Key Terms Explained
- ACOS (Advertising Cost of Sales)
- Amazon PPC metric: Ad Spend ÷ Ad Revenue × 100. Break-even ACOS = Profit Margin %. If you make 30% margin, your break-even ACOS is 30%. Below that = profitable ads.
- ROAS (Return on Ad Spend)
- Revenue generated per pound/dollar of ad spend. ROAS = Revenue ÷ Ad Spend. A 4× ROAS means £4 revenue per £1 spent. Target ROAS varies by margin — higher margin businesses can sustain lower ROAS.
- AOV (Average Order Value)
- Total Revenue ÷ Number of Orders. Increasing AOV (via bundles, upsells, or minimum order thresholds) is often the fastest lever for revenue growth without additional traffic costs.
- FBA (Fulfilled by Amazon)
- Amazon's fulfilment service where sellers ship inventory to Amazon warehouses. Amazon picks, packs, ships, and handles returns. Fees include fulfilment fee (weight-based), storage fee, and referral fee (% of sale price).
- Conversion Rate
- The percentage of visitors who complete a purchase. Ecommerce conversion rate = Orders ÷ Sessions × 100. Average ecommerce conversion rate: 1–3%. Above 3.5% is considered strong.
Frequently Asked Questions
How do Amazon FBA fees work?
Amazon FBA charges: (1) Referral fee: 6–15% of sale price depending on category; (2) Fulfilment fee: based on product size and weight, typically $3–8 for standard size; (3) Storage fee: monthly charge per cubic foot. Use the FBA calculator to see your exact costs before listing.
What is a good profit margin for Amazon FBA products?
After all Amazon fees (referral, FBA, advertising), most successful FBA sellers target 20–30%+ net margin. Margins below 15% leave little buffer for price competition or fee increases. Products with margins below 10% after fees are difficult to make work profitably.
What ROAS should I target for my ads?
Target ROAS depends on your margin. If your gross margin is 40%, you need ROAS above 1/0.40 = 2.5× just to break even on ad spend (before other costs). Profitable campaigns typically target 3–5× ROAS for most products, higher for low-margin categories.
How do I increase my ecommerce conversion rate?
High-impact improvements: better product photography, faster page load times, simplified checkout (reduce steps), clear return policy, customer reviews, and mobile optimisation. Even a 0.5% conversion rate improvement on 10,000 monthly visitors generates 50 additional orders per month.