Forecasting your PPC budget isn’t guesswork, it’s strategy. For B2B marketers, a well-built forecast means clearer investment decisions, fewer surprises, and better alignment with sales goals.
In this guide we’ll walk you through the key metrics, step-by-step planning process, and common mistakes to avoid, plus share a free B2B-focused forecast template to simplify your next campaign budget.
Key Takeaways: PPC Budget Forecasting in 2025
- PPC forecasting isn’t optional, it’s essential for aligning budget with business outcomes.
- Start with solid inputs like CPC, CVR, and sales conversion rates to build accurate models.
- Use forecasting to support strategic decisions, not just to fill in spreadsheets.
- Plan by funnel stage, account for seasonality, and always reserve budget for testing.
What Is PPC Budget Forecasting and Why Does It Matter?
PPC budget forecasting is the process of estimating how much ad spend is needed to achieve specific marketing goals before you spend a penny.
For B2B marketers, this means tying campaign costs to funnel metrics like leads, SQLs, or pipeline value. It’s not just about predicting spend, but about aligning every pound with a measurable outcome.
B2B cycles tend to be longer as buying committees are larger and lead quality matters more than volume. A solid forecast accounts for these nuances, helping you align marketing with sales goals, justify spend, and avoid surprise shortfalls during planning cycles.
The Cost of Guesswork in Paid Media
Let’s say your team allocates £10,000 to a LinkedIn campaign based on last year’s results without factoring in higher CPCs or new funnel goals.
Fast-forward three months: you’re over budget, under target, and stuck explaining the shortfall. On the flip side, under-forecasting can leave high-performing campaigns throttled by budget caps. Either way, guesswork leads to missed opportunities and misalignment with commercial goals which is especially painful for scale-ups operating under pressure.
How Forecasting Supports Smarter Investment Decisions
Done right, forecasting becomes a strategic planning tool, not just a spreadsheet exercise. It helps you pace spend across the quarter, test new channels with intention, and make proactive decisions when performance shifts.
Forecasting enables scenario planning (‘what happens if we increase budget by 20%?’) and forces early clarity on goals and KPIs. For marketing leads, it’s also a powerful way to secure stakeholder buy-in by speaking the language of expected outcomes.
Key Metrics That Impact Your PPC Budget
Before you can build an accurate PPC budget forecast, you need to understand the numbers that shape it.
Each one plays a role in determining how much you should spend, where, and why. Whether you’re reporting to the CMO or justifying spending to finance, these metrics help you build a forecast rooted in reality.
Click-Through Rate (CTR) and Conversion Rate (CVR)
CTR refers to the number of clicks your ad has received, while CVR tells you how many of those clicks actually turn into leads or sales.
Together, they’re the starting point for any forecast. Use your historical campaign data where possible, or industry averages can be helpful for benchmarking, but your past performance is more predictive. For example, if your LinkedIn campaigns typically convert at 2%, budgeting based on a 5% benchmark could tank your results.
Average Cost-Per-Click (CPC) Across Platforms
Your CPCs will vary significantly across Google, LinkedIn, Meta, and other platforms, especially in B2B. Expect higher CPCs on LinkedIn due to targeting precision and intent quality. Google Ads may offer lower CPCs but broader, less qualified traffic. Forecasting by platform ensures your budget isn’t skewed by one-size-fits-all expectations.
Monthly Search Volume and Intent Alignment
Just because a keyword has a high search volume doesn’t mean it deserves a budget. Focus on keywords with strong commercial intent, those that signal someone is ready to engage.
Group your keywords into ‘intent buckets’ (top, middle, bottom of funnel) and forecast accordingly. This prevents wasted spend on traffic that doesn’t convert and ensures your forecast reflects actual opportunity.
Return on Ad Spend (ROAS)
The ‘Return on Investment’ will tell you just how much revenue you’re generating for the amount spent. It’s one of the clearest indicators of PPC efficiency because it directly answers the question of ‘are we making more than we’re spending?’
It ties spending directly to revenue and reveals over or under-investment. For example, a low ROAS could mean poor targeting, high CPCs or perhaps a broken funnel, whereas a high ROAS signals your strategy is working.
Customer Acquisition Cost (CAC) and Customer Lifetime Value (LTV)
CAC is the total cost of turning a prospect into a customer. LTV is how much that customer is worth over time.
In B2B, both numbers vary widely across segments. Use rolling averages across at least one quarter to smooth out anomalies. Forecasts that ignore CAC often lead to unrealistic ROAS targets, while ignoring LTV can result in underinvesting in high-value acquisition channels.
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How to Forecast Your PPC Budget Step by Step
Forecasting your PPC budget isn’t about finding a single ‘right’ number; it’s about building a range of data-backed scenarios you can adjust and defend. This step-by-step guide helps you structure your thinking, quantify your assumptions, and turn raw inputs into actionable budgets.
Set Campaign Goals and Define Success Metrics
Before you even look at spending, get crystal clear on your campaign goals. Are you trying to build awareness or generate qualified leads?
Each goal comes with different success metrics. CPM might matter for awareness, while CPL or CAC is critical for lead gen. Set your KPIs first so your budget can work backwards from the outcomes that matter.
Estimate Traffic Volume and Conversions
Start with your keyword plan or target audience size. Use tools like Google Keyword Planner, Meta Audience Insights, or LinkedIn Campaign Manager to estimate traffic potential. Then, apply your expected CTR and CVR to forecast conversions. For example:
- Projected clicks = (Search volume) x (CTR)
- Projected leads = (Projected clicks) x (CVR)
This gives you a rough idea of how much traffic and how many leads to expect for a given budget.
Map Your Sales Funnel and Assign Budget by Stage
In B2B, not all traffic is created equal. Some campaigns are meant to educate, others to convert. Break your budget down by funnel stage (top, middle, bottom) and assign spend accordingly. A typical split might be:
- 50% top-of-funnel (TOFU)
- 30% middle-of-funnel (MOFU)
- 20% bottom-of-funnel (BOFU)
Weighting your spend this way ensures coverage across the buyer journey and improves conversion efficiency downstream.
Account for Testing, Scaling, and Seasonality
No forecast is complete without buffers. Allocate ~10-15% of your budget for testing new channels, creatives, or messaging.
If you’re forecasting Q4 spend, factor in higher CPCs during peak periods. Look at historical seasonal trends in your industry and adjust pacing accordingly. This flexibility helps avoid budget shortfalls or missed scale opportunities.
Build Out Different Budget Scenarios (Conservative vs Aggressive)
Finally, model at least three versions of your budget: conservative, expected, and aggressive. This allows you to pivot quickly based on performance or leadership direction. A simple structure might look like:
- Conservative: Lower traffic assumptions, cautious CAC
- Expected: Based on current averages
- Aggressive: Higher spend, scaling assumptions, faster ROI expectations
These scenarios help you make faster decisions and advocate for additional budget when needed.
PPC Forecasting for B2B vs B2C: What’s the Difference?
Forecasting for B2B isn’t just a more complex version of B2C; it’s fundamentally different. The metrics may look similar, but the context, sales cycles, and budget strategy shift dramatically.
Sales Cycles and Lead Quality
B2B sales cycles can be longer and are often multi-staged. A single PPC lead might take weeks or months to convert. That means you can’t rely on click-to-lead metrics alone. Your forecast should factor in how many leads typically become MQLs, then SQLs, and eventually opportunities. If 100 leads only yield 10 quality conversations, that drastically changes how much budget you need to hit pipeline targets.
Attribution and Multi-Touch Complexity
While some B2C journeys can be quick and conversion-driven, some, especially in considered purchases like finance, healthcare, or luxury goods, also involve multiple touchpoints.
In B2B, though, multi-touch attribution is the norm rather than the exception. Prospects often engage with multiple ads, visit your site organically, click a retargeting campaign, attend a webinar, and have several calls with sales, all before converting. That makes accurate forecasting harder.
Your PPC forecast should acknowledge assist value, not just last-click impact. Tools like HubSpot, Salesforce, or even Google Ads’ conversion paths can help model this. Forecasting only on final-click metrics risks undervaluing key campaigns, especially those at the top or middle of the funnel.
Budget Pacing Based on Deal Size and Velocity
When deal sizes are large and sales cycles are slow, your budget pacing needs to reflect that lag. In some B2B sectors, you might not see ROI until 60-90 days after initial ad spend. That doesn’t mean the campaign failed, it means the return is staggered. Your forecast should account for delayed conversion and map spend against when pipeline value is likely to materialise.
Common PPC Budgeting Mistakes to Avoid
Even the most experienced marketing teams fall into avoidable traps when planning PPC budgets. These mistakes often come down to overconfidence in platform tools, underestimating variables like sales cycles or LTV, and treating forecasts as fixed predictions rather than flexible models.
By recognising where things typically go wrong, you can make better decisions, avoid wasted spend, and build forecasts that hold up under scrutiny.
Overreliance on Platform Estimates
It’s tempting to lean on Google or LinkedIn’s forecast tools as they’re easy and give you neat-looking projections. But those estimates often paint an overly optimistic picture.
They don’t account for your unique audience behaviour, historical performance, or real conversion quality. Treat them as directional, not definitive. If your budget is based solely on these tools, you risk overspending without the results to match.
Ignoring Lifetime Value or Sales Team Input
Budgeting without input from sales, or without considering LTV, means you’re planning in isolation. A lead worth £10,000 in lifetime revenue deserves a very different budget than one worth £500. Yet many forecasts focus only on CPL or CAC, missing the bigger picture.
Bring sales into the conversation early and validate your assumptions about deal size, conversion rates, and what ‘qualified’ really means. It’ll make your forecast more accurate and your budget easier to defend.
Budgeting Without Factoring in Growth Targets
Too many forecasts are based on ‘what we did last quarter’ rather than ‘what we need to achieve next.’ If your business has aggressive revenue goals, your PPC budget has to scale accordingly, especially if paid media is a primary acquisition channel.
Reverse-engineering spend based on pipeline targets (and win rates) gives you a more strategic starting point than just replicating past activity.
Not Reserving Spend for Testing and Optimisation
All budgets should have breathing room. If every pound is pre-assigned to performance campaigns, you leave no space for experimentation, which will mean no new ad copy, no testing a new platform, no refining audiences.
A good rule of thumb is to reserve 10-15% of your monthly PPC budget for learning and iteration. Without it, your campaigns may perform adequately, but never get meaningfully better.
Wrapping Up: PPC Budget Forecasting With Confidence
PPC budget forecasting is about being prepared. The more intentional you are with your inputs, assumptions, and planning, the more confidently you can invest, adapt, and deliver results that matter.
Whether you’re justifying spend to leadership or fine-tuning campaign performance, a strong forecast gives you the structure to do both.
Use the tools and frameworks we’ve shared here as a foundation. Then, refine them based on your business goals, sales data, and what you learn in-market. Remember that forecasting shouldn’t be a one-off task, but a habit. And when you treat it as such, your paid media strategy becomes not just more efficient, but more accountable.
Ready to turn insight into action?
If you’re looking to bring more clarity, strategy, and accountability to your paid media spend, our team can help. We’ve guided dozens of B2B brands through building data-backed PPC forecasts that actually drive pipeline growth.
Get in touch to discuss your goals and see how we can help you plan and manage your next campaign with confidence.
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FAQs on PPC Budget Forecasting
Below, we’re addressing some of the most common questions marketers face when planning or defending their paid media budgets.
How much should I spend on PPC monthly?
There’s no universal figure, it depends on your goals, sales cycle, and CAC targets. A useful approach is to work backwards from your revenue targets: estimate how many leads (and at what quality) you need to generate that pipeline, then calculate the spend required based on your average CPC and CVR. For many B2B firms, starting around 5-10% of revenue allocated to paid media is a helpful baseline, adjusted by funnel efficiency.
What’s a good ROAS or CAC benchmark for B2B?
How often should I update my PPC forecast?
What tools help with PPC forecasting?
Can I use Google Ads estimates alone?
Should I include brand and non-brand separately?
What’s the best way to track forecasts vs actuals?
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More about the author
Sam Searle
Head of Digital
Common Ground’s longest-serving employee, Sam spearheaded our PPC efforts alone for years, before eventually building her team and becoming head of all digital operations in the business. Sam still lives and breathes PPC, and has a hand in all of our paid work.
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