How to Build a Google Ads Budget Forecast with Keyword Planner

Before you put a single euro into Google Ads, you want to know what you get back for it. A budget forecast gives you that insight upfront: it estimates how many clicks your keywords can deliver, what those clicks cost on average and roughly what a month of advertising will therefore cost. Not an exact prediction, but a substantiated scenario that lets you have a conversation instead of taking a gamble. In this article we show how to build a Google Ads budget forecast with Google’s Keyword Planner that actually holds up, and how to translate those figures into a budget you can defend.

This is part of the broader question of how paid search works. Read our pillar what is SEA first if you want to cover the basics of search advertising.

What a budget forecast is and is not

A forecast is an estimate of what your campaign can do based on Google’s historical data. It does not tell you what you are going to earn, it tells you what a given click volume at a given click price costs approximately. That is a big difference.

The value lies in the direction, not in the decimal. A good forecast answers questions like: is there enough search volume to hit my target? Are click prices in my sector around 1 euro or around 12 euros? Does this channel suit my margin at all? Those are decisions you are better off making before you commit the budget than after.

Do not talk yourself into optimistic numbers. The figures in a forecast come from averages across many advertisers. Your result depends on your keywords, your ads and the quality of your landing page. Treat the forecast as the upper bound of a conversation, not as a commitment.

Step 1: gather your search volume in Keyword Planner

Keyword Planner is free and sits in every Google Ads account. Start with the “Discover new keywords” tab and enter a few terms your customers would use. Not the name of your product as you know it, but the words someone types when they are still looking for your solution.

The tool gives you an average monthly search volume per keyword. Watch out for two things here. One: the volume is often shown in a wide range, so do not take the top end as a certainty. Two: high search volume does not automatically mean high value. A broad term attracts a lot of browsers still orienting themselves, while a specific term with low volume sometimes brings in exactly the buyer-ready searcher. Volume without purchase intent is an expensive pastime.

So filter on intent, not just on numbers. Terms with words like “buy”, “quote”, “specialist” or a concrete place name say more about buying readiness than a general term with ten times the volume.

Step 2: read the CPC range properly

Alongside the volume, Keyword Planner shows an expected click price per keyword as a low and a high bid. That is your CPC range, and for your forecast it matters more than the volume. Because it is the click price that eats your budget.

Use the top of the range as your working figure. Advertisers who structurally bid at the bottom also show up less often at the top of the results, and it is precisely those top positions that get the clicks. If you calculate with the low bid, you build a forecast that turns out too optimistic in practice.

A simple worked example to show the logic, not as a benchmark: suppose a set of keywords together has 1,000 searches per month and you realistically win 1 in 20 clicks, then you are looking at some 50 clicks. If a click costs 4 euros on average, you are talking about 200 euros of media budget for those terms. If your click price doubles to 8 euros, your budget doubles with it without you buying a single extra click. That is why CPC is the dial you watch most closely. If you want to dig deeper into that cost side, read Google Ads cost.

Step 3: from clicks to cost per lead

A forecast that stops at clicks is half the job. Clicks do not pay your bills, leads and deals do. So add the third variable: your conversion rate, the percentage of visitors who actually submit an enquiry.

With three numbers you have a usable forecast: expected click volume, average CPC and conversion rate. Suppose 50 clicks at 4 euros cost you 200 euros, and 1 in 25 visitors submits an enquiry. That budget then delivers roughly two leads, at a cost per lead of around 100 euros. Now you have a figure you can base a decision on. Apply that chain of calculations to your entire keyword list and you have a forecast that is not about clicks, but about enquiries. If you want to build that exercise up from your lead target, read Google Ads budget.

Leave room for the learning period

A forecast shows an average, not a trajectory. In practice, a new campaign performs worse in the first weeks than your forecast suggests. The algorithm is still collecting conversion data and does not yet know which searchers deliver value. In that phase you are paying for clicks the system uses to learn.

Factor that learning period into your expectations. Do not judge a campaign on one week against your forecast, but give it time to gather enough conversion signals. A budget too tight to build up that data stays stuck in the learning phase and wrongly confirms the idea that Google Ads does not work.

Make the forecast a growth decision, not a click budget

The real value of a budget forecast is unlocked as soon as you connect it to what happens after the click. With offline conversion measurement and lead-to-deal attribution, you see not only which clicks became leads, but which leads also became customers. Then you steer your forecast and your budget towards the keywords that build pipeline, and not towards the terms that only push up your click counter.

That is how paid search becomes the fast acquisition layer of one orchestration rather than a standalone cost item you feed on gut feel. A forecast that starts at click volume and ends at cost per deal is exactly how we as a Google Ads agency substantiate a budget: not on what it costs to be seen, but on what it delivers in customers.

Ready to run the numbers on your budget upfront?

A budget forecast takes the guesswork out of your decision to start with Google Ads. With click volume, CPC and conversion likelihood you know upfront which range your campaign plays in, and with attribution you know afterwards whether those euros turned into deals. Want to build a substantiated forecast together for your keywords and market? Get in touch and we will run the numbers with you.