Summary
- Minimum budget for Smart Bidding: 30× your CPA per month. If your CPA is 250 CZK (≈ €10), you need at least 7,500 CZK (≈ €300) a month per campaign. Below that, the algorithm won't learn.
- For PMax you need at least €50 a day (about 1,250 CZK), ideally €100. For Demand Gen at least 1,500 CZK (≈ €60) a day. Search campaigns are the most flexible — they work even on smaller budgets.
- The formula for an e-commerce store: Target number of orders × CPA = monthly budget. Want 200 orders a month at a 300 CZK (≈ €12) CPA? Budget = 60,000 CZK (≈ €2,400). Simple maths.
- Budget split in 2026: Search/Shopping 50–60%, PMax 25–35%, Demand Gen 10–15%. The exact ratio depends on whether you want to grow (more Demand Gen) or maximise ROAS (more Search).
- Average CPC on the Czech market: Search 5–25 CZK (≈ €0.20–1.00), Shopping 3–12 CZK (≈ €0.12–0.50), Display 1–5 CZK (≈ €0.04–0.20), YouTube 0.50–3 CZK (≈ €0.02–0.12). Industries like finance and insurance have CPCs above 50 CZK (≈ €2).
The right budget isn't a number you make up. It's a calculation that comes from three things: how much a customer costs you (CPA), how many customers you want each month, and how much data the algorithm needs to function. Spend too little and Smart Bidding won't learn and you'll throw the money away. Spend too much without the right setup and you'll throw the money away too — just faster.
In this article we'll show you how to calculate your budget, how to split it across campaign types and what the real benchmarks are for the Czech market.
Formula 1: The minimum you need for Smart Bidding to work
This is the absolute baseline. Smart Bidding — whether Target CPA, Target ROAS, Maximize Conversions or Maximize Conversion Value — needs data. Without data it's roulette.
The minimum rule
30 conversions in 30 days per campaign. That's the threshold below which Smart Bidding doesn't have enough data to learn. For Target ROAS, Google recommends ideally 50+ conversions, and 100+ is best.
From that comes a simple formula:
Minimum monthly budget = 30 × your CPA
| Your CPA | Minimum budget/month/campaign |
|---|---|
| 100 CZK (≈ €4) | 3,000 CZK (≈ €120) |
| 250 CZK (≈ €10) | 7,500 CZK (≈ €300) |
| 500 CZK (≈ €20) | 15,000 CZK (≈ €600) |
| 1,000 CZK (≈ €40) | 30,000 CZK (≈ €1,200) |
| 2,500 CZK (≈ €100) | 75,000 CZK (≈ €3,000) |
If your CPA is 500 CZK (≈ €20) and your campaign budget is 5,000 CZK (≈ €200) a month, Smart Bidding gets at most 10 conversions. That's too few for any meaningful learning. The results will fluctuate and you'll end up frustrated.
What if you don't know your CPA? Go to Google Ads → Campaigns → Columns → add "Cost / conv." If you don't have campaigns yet, use an estimate: the average CPA in Czech e-commerce is 150–500 CZK (≈ €6–20), and 300–1,500 CZK (≈ €12–60) for services.
Formula 2: How much you need for a target number of orders
This is the formula that makes sense to store owners, because it starts from a business goal.
Monthly budget = Target number of orders × CPA
Example:
- You want 300 orders a month from Google Ads
- Your average CPA is 200 CZK (≈ €8)
- Budget = 300 × 200 = 60,000 CZK (≈ €2,400)/month
Simple, but the key is a realistic CPA estimate. This is where benchmarks help:
Average CPA by business type in the Czech Republic (2026 estimates)
| Business type | Typical CPA |
|---|---|
| E-commerce (fashion, accessories) | 150–400 CZK (≈ €6–16) |
| E-commerce (electronics) | 200–600 CZK (≈ €8–24) |
| E-commerce (groceries, drugstore) | 80–250 CZK (≈ €3–10) |
| E-commerce (furniture, interiors) | 500–1,500 CZK (≈ €20–60) |
| SaaS / software | 500–2,000 CZK (≈ €20–80) |
| Services (B2C) | 300–800 CZK (≈ €12–32) |
| B2B lead generation | 500–3,000 CZK (≈ €20–120) |
These figures are indicative — a lot depends on competition, the quality of your site, your conversion rate and dozens of other factors. But as a starting point for planning your budget, they'll do the job.
Formula 3: Working backwards from ROAS
For e-commerce stores that think in terms of ROAS (return on ad spend), this formula is more useful:
Monthly budget = Target revenue from ads / ROAS
Example:
- You want 500,000 CZK (≈ €20,000) a month in revenue from Google Ads
- Your realistic ROAS is 500% (5 CZK in revenue for every crown spent on ads)
- Budget = 500,000 / 5 = 100,000 CZK (≈ €4,000)/month
And how much of that is profit? That depends on your margin. A store with a 40% margin needs a ROAS of at least 300–400% to be in profit (after deducting the cost of goods, shipping and overheads). Top campaigns reach 600–1,200%.
How to split your budget across campaign types
You've got a number — let's say 150,000 CZK (≈ €6,000) a month. How do you split it?
Recommended split for an e-commerce store in 2026
| Campaign type | Share of budget | At 150,000 CZK (≈ €6,000) |
|---|---|---|
| Search + Shopping | 50–60% | 75,000–90,000 CZK (≈ €3,000–3,600) |
| Performance Max | 25–35% | 37,500–52,500 CZK (≈ €1,500–2,100) |
| Demand Gen | 10–15% | 15,000–22,500 CZK (≈ €600–900) |
Why this ratio? Search and Shopping are bottom-of-funnel — they reach people who are actively searching for your products. This is where ROAS is highest and conversions are cheapest. PMax widens your reach across channels. Demand Gen builds awareness with new audiences.
Adjusting for your goal
Maximising ROAS (a conservative approach):
- Search/Shopping: 65%
- PMax: 30%
- Demand Gen: 5%
Growth and scaling (an aggressive approach):
- Search/Shopping: 40%
- PMax: 35%
- Demand Gen: 25%
Important: only turn on Demand Gen once Search and Shopping are profitable. It's not a channel you start on — it's a channel you expand into.
Minimum budgets by campaign type
| Campaign type | Minimum/day | Minimum/month |
|---|---|---|
| Search | 200 CZK (≈ €8) | 6,000 CZK (≈ €240) |
| Shopping | 300 CZK (≈ €12) | 9,000 CZK (≈ €360) |
| Performance Max | 1,250 CZK (€50) | 37,500 CZK (≈ €1,500) |
| Demand Gen | 1,500 CZK (≈ €60) | 45,000 CZK (≈ €1,800) |
| AI Max for Search | 1,250 CZK (≈ €50) | 37,500 CZK (≈ €1,500) |
Below these thresholds the algorithm doesn't have enough data to optimise. It's better to invest more into fewer campaigns than a little into many.
Average CPC on the Czech market — what you'll pay per click
The cost per click (CPC) varies by channel, industry and competition. Here are the indicative ranges for the Czech market in 2026:
CPC by channel
| Channel | Typical CPC |
|---|---|
| Search (general) | 5–25 CZK (≈ €0.20–1.00) |
| Search (branded) | 1–5 CZK (≈ €0.04–0.20) |
| Shopping | 3–12 CZK (≈ €0.12–0.50) |
| Display | 1–5 CZK (≈ €0.04–0.20) |
| YouTube | 0.50–3 CZK (≈ €0.02–0.12) |
| Demand Gen | 2–10 CZK (≈ €0.08–0.40) |
CPC by industry (Search)
| Industry | Typical CPC |
|---|---|
| Fashion, apparel | 5–15 CZK (≈ €0.20–0.60) |
| Electronics | 8–25 CZK (≈ €0.32–1.00) |
| Groceries, drugstore | 3–10 CZK (≈ €0.12–0.40) |
| Furniture, interiors | 10–30 CZK (≈ €0.40–1.20) |
| Finance, insurance | 20–80 CZK (≈ €0.80–3.20) |
| Legal services | 30–60 CZK (≈ €1.20–2.40) |
| Travel | 8–25 CZK (≈ €0.32–1.00) |
| Health, fitness | 5–20 CZK (≈ €0.20–0.80) |
These figures are for rough planning. Actual CPC depends on competition, ad quality (Quality Score), targeting and a range of other factors.
When to increase your budget (and when not to)
Increase your budget if:
Your Impression Share is below 70% due to budget. That means your ads aren't showing because you're running out of budget. You're missing out on conversions.
Your ROAS is above your target and the campaign is stable. That's a signal the algorithm is working and more money = more conversions at the same efficiency.
Your site's conversion rate has improved. A better site = a lower CPA = room to scale.
Don't increase your budget if:
Your CPA is above target and rising. More money won't fix the problem — fix the campaigns first.
You don't have proper tracking. Without Enhanced Conversions and Consent Mode V2 you don't know what's working. Fix the tracking, then scale.
Your site doesn't have a good enough conversion rate. The average for Czech e-commerce stores is 1–3%. If you're below 1%, invest in the site first, not the ads.
The rule: increase your budget by no more than 20% at a time and wait 2 weeks for it to stabilise. Big jumps restart the Smart Bidding learning.
At LK Media we start with a conservative budget, prove the results and then scale. We never recommend "just throw 200,000 at it and see what happens." That's a recipe for disappointment.
In closing
A Google Ads budget isn't a guessing game. It's a calculation based on your CPA, your target number of orders and the minimum requirements of the algorithms. The three formulas in this article give you a clear number you can work with.
Start with the 30× CPA formula — that's the minimum for Smart Bidding to work. Then work out how many orders you want and set your budget accordingly. And above all: more money into fewer campaigns beats a little money into many.
Want help planning the budget for your e-commerce store? Email info@lkmedia.cz — we'll work it out together based on your real data.
FAQ
What's the minimum I should invest in Google Ads?
The absolute minimum for Search campaigns is around 6,000 CZK (≈ €240) a month (200 CZK / ≈ €8 a day). For Smart Bidding to work you need a budget of at least 30× your CPA per campaign. For PMax the minimum is around 37,500 CZK (≈ €1,500) a month (1,250 CZK / ≈ €50 a day). Below these thresholds the algorithm doesn't have enough data and the results will be unstable.
How much does a click cost in Google Ads on the Czech market?
It depends on the industry and campaign type. Search campaigns: 5–25 CZK (≈ €0.20–1.00) per click (finance and legal services even 50–80 CZK / ≈ €2–3.20). Shopping: 3–12 CZK (≈ €0.12–0.50). Display: 1–5 CZK (≈ €0.04–0.20). YouTube: 0.50–3 CZK (≈ €0.02–0.12). Branded search: 1–5 CZK (≈ €0.04–0.20). Actual CPC depends on competition, ad quality and other factors.
How should I split my budget across campaigns?
For an e-commerce store in 2026 we recommend: Search + Shopping 50–60%, Performance Max 25–35%, Demand Gen 10–15%. If you want to maximise ROAS, put more into Search/Shopping. If you want to grow, add to Demand Gen. Only turn on Demand Gen once Search and Shopping are profitable.
What ROAS do I need for Google Ads to pay off?
It depends on your margin. A store with a 40% margin needs a ROAS of at least 300–400% to cover the cost of goods, shipping and overheads. With a 60% margin a ROAS of 200–250% is enough. Top campaigns reach 600–1,200%. The formula: minimum ROAS = 100% / your margin as a percentage × 100.
When should I increase my Google Ads budget?
When your campaigns consistently hit your target CPA/ROAS, your Impression Share is limited by budget (below 70%) and your tracking is in order. Increase by no more than 20% at a time and wait 2 weeks for it to stabilise. Don't increase if your CPA is rising, your tracking isn't right or your site has a low conversion rate.
