How to Set Your SaaS Paid Acquisition Budget (CPL, CPQL & LTV:CAC)

One of the biggest reasons SaaS paid acquisition fails isn’t poor campaign setup, lack of optimisation, or the wrong channels.

It’s budgeting.

More specifically: SaaS teams setting goals that their budget can’t support.

Whether you're working with an agency, a freelancer, or you’ve just hired your first in-house performance marketer, your paid acquisition goals must be backed by math, not hope.

Because here’s the truth no one loves to hear: If you don’t allocate the budget your goals require, your paid marketing team will fail — no matter how good they are.

In this article, I’ll walk you through two reliable ways to calculate a realistic SaaS ad budget:

1. CPL / CPQL-based budget modelling

2. LTV:CAC-based budget modelling (perfect for subscription businesses)

Both frameworks are simple, practical, and designed for early-stage or scaling SaaS companies.

1. The CPL / CPQL Method: Ideal for Lead-Gen Focused SaaS

If your goal is to generate leads or qualified leads, start with a conversion-based budget model.

Let’s look at a simplified example.

Inputs:

• Target monthly leads: 28

• Target CPL: €2,000

• Testing buffer: 20%

Outputs:

• Minimal viable budget: €56,000 / month

• Minimal viable budget + buffer: €67,200 / month

This method works only if your primary KPI is CPL or CPQL.

But what if your campaign doesn’t produce enough conversions for Google Ads to optimise effectively?

When CPQL is Too Low to Optimise

If your MQL → SQL volume is low (common in niche B2B SaaS), Google won’t have enough signal strength.

In that case, you have two options:

Option A — Optimise for Both

Use both Events (Lead + MQL) until MQL volume grows enough for a reliable optimisation window.

Option B — Optimise for Value

Assign higher conversion value to MQLs or Activation events, while still capturing Leads as low-value conversions.

This tells Google:
“Yes, generate leads but aim for the higher-quality ones.”

This is a practical workaround for early-stage SaaS advertisers who don’t yet have the volume their ideal KPI requires.

2. The LTV:CAC Method: Best for Subscription SaaS

If your business runs on MRR, this method is essential.

Here’s an example using a realistic subscription model:

Inputs:

• ARPU: €35

• Average lifetime: 12 months

• Target LTV:CAC ratio: 3:1

• Target new customers per month: 100

• Testing buffer: 20%

Outputs:

• Minimal viable budget: €14,000 / month

• Minimal viable budget + buffer: €16,800 / month

How the math works

• €35 × 12 = €420 LTV

• With a 3:1 target, your max CAC = €140

• To acquire 100 customers → €140 × 100 = €14,000

• Add 20% testing buffer → €16,800

This is why many SaaS teams run into trouble:

📉 They target 100 new customers but only budget €8k
📉 They want a 3:1 LTV:CAC but only fund campaigns enough to produce a 7:1 ratio (meaning they’re growing too slowly)
📉 They expect CAC to drop… while cutting budget

Paid acquisition cannot do magic.
It can only work within the constraints you set.

The Hard Truth: Most SaaS Teams Underfund Their Targets

The disconnect is almost always:

• Ambitious acquisition goals

• Limited budgets

• Unrealistic timelines

No matter who manages your ads — a freelancer, an agency, or an internal team — they can optimise performance but they cannot outrun flawed economics.

A profitable paid media program is built on:

✔️ Realistic KPIs
✔️ Budget aligned with volume expectations
✔️ Proper buffers for testing and optimisation
✔️ Clear targets for CPL, CPQL, CAC and ROAS

Without these, even the best marketer will struggle.

If You're a SaaS Founder or CMO, Here’s What to Do Next

Before launching or scaling your paid campaigns:

1. Run both budget models (CPL/CPQL + LTV:CAC)

2. See where the numbers align or clash

3. Adjust your targets or increase your budget

4. Set one primary KPI (efficiency or growth), not both

5. Ensure your marketer or agency is working with correct unit economics

This is the foundation of successful paid acquisition.