How the Bid Formula Works
The math behind optimal Amazon PPC bids is surprisingly simple once you understand the relationship between bid, conversion rate and ACoS:
The logic: if you convert 8% of clicks, each sale takes ~12.5 clicks on average (1 ÷ 0.08). At ₹15.98 per click, 12.5 clicks cost ₹200 — which is 20% of a ₹999 sale. That is your target ACoS.
Break-Even CPC vs Max Bid vs Recommended Bid
- Break-even CPC — the bid at which ACoS equals your pre-ad margin. Every rupee above this loses you money. Never exceed this on any keyword unless strategically (defensive branded, new launch impressions).
- Max bid — the highest bid that still hits your target ACoS (i.e., keeps your desired net profit). This is your ceiling for scaling winning keywords.
- Recommended starting bid — 70% of max bid. Gives you room to raise bids on winners once data comes in, without starting at your ceiling and having to drop down.
Where Conversion Rate Comes From
This is the tricky input for new campaigns — you do not know your true CVR yet. Three ways to estimate:
- Existing organic sales data. If your organic detail page CVR is 10%, ad CVR will be similar (often slightly lower, 8-10%).
- Category benchmarks. Amazon India median CVRs: Apparel 4-7%, Electronics 6-10%, Beauty 7-12%, Home & Kitchen 5-9%, Grocery 8-14%.
- Conservative estimate. Start at 5% CVR for any new launch. You will almost certainly beat this, which gives you headroom to bid up winners.
After 14 days of data, plug your actual CVR into this calculator and recompute your max bids. Recompute every 30 days for mature campaigns as CVR drifts with seasonality.
Bidding by Keyword Intent Tier
One-size-fits-all bidding is suboptimal. Tier your keywords and apply different bid multipliers to each:
| Intent Tier | Bid Multiplier | Rationale |
|---|---|---|
| Branded | 120% of max bid | CVR is 2-4x category average; defend top-of-search. |
| Product-specific | 100% | Standard commercial intent; bid at max. |
| Competitor | 85% | Lower CVR; factor in brand switching cost. |
| Category/generic | 70% | High impressions, lower intent; be cautious. |
| Exploratory | 50% | New keywords with no data; cheap testing. |
Automate this with eVanik
eVanik's bid automation recomputes optimal bids every 6 hours based on 14-day rolling CVR and ACoS data — no more monthly spreadsheet exercises. Bid modifiers apply automatically by intent tier. Most customers see 25-40% ACoS reduction within 60 days.
