The question of how much to spend on digital advertising doesn't have a single correct answer. But it does have a rational approach, one that most small business owners haven't been shown.
The typical advice ("spend 7-8% of revenue on marketing") isn't wrong exactly, but it's also not very useful. It doesn't tell you whether advertising makes sense for your business at all, what channel to put the money into, or how to know if what you're spending is working.
Here's a better framework.
Start With What a Customer Is Worth
Before you set an ad budget, you need to know what a new customer is worth to your business. This is the number that everything else should be calculated against.
Customer lifetime value (CLV) is the total revenue a customer generates over their entire relationship with your business. For a landscaping company with clients who spend $3,000 per season and stay for an average of four years, CLV is roughly $12,000.
Gross profit from a new customer is a more conservative figure: the revenue from a single job or transaction minus your direct costs. For that same landscaper, a new seasonal contract worth $3,000 with 50% gross margins produces $1,500 in gross profit.
Now you have a ceiling: you should be willing to spend up to some fraction of that gross profit to acquire a customer. A reasonable target is to spend no more than 20–30% of the gross profit from a new customer to acquire them. For the landscaper, that means $300–$450 in advertising spend per new customer is sustainable.
If your advertising produces new customers at $200 in ad spend, that's excellent. If it's costing $600 per new customer, you're losing money on the channel and need to either improve the campaign or reconsider.
Working Backwards to a Monthly Budget
Once you know your target cost per customer, you can work backwards to a monthly budget.
Here's the math:
- Target cost per acquired customer: $350
- Your website's lead conversion rate (what percentage of visitors become leads): let's say 3%
- Your lead-to-customer conversion rate (how many leads become paying customers): let's say 25%
- Cost per click in your market and category: let's say $8
To get one customer, you need:
- 1 customer ÷ 25% close rate = 4 leads
- 4 leads ÷ 3% conversion rate = 133 website visitors
- 133 visitors × $8 CPC = $1,064 in ad spend per customer
If your target is $350/customer and reality is $1,064/customer, something needs to change: your landing page conversion rate, your lead follow-up process, or your cost per click.
This kind of backwards calculation is what a well-run advertising campaign is built around, not gut feel about percentages.
Platform Minimums That Actually Work
The revenue-percentage rule doesn't account for minimum effective spend. Below certain thresholds, paid advertising platforms don't have enough data to optimize properly.
Google Ads: A realistic minimum for a local service business is $500/month in ad spend, not including management fees. Below that, you're not generating enough clicks and conversions to train the algorithm effectively. For competitive categories (legal, home services, medical), expect to spend $1,500–$3,000+/month to generate meaningful volume.
Meta Ads (Facebook/Instagram): $500/month is a workable starting budget for testing creative and targeting in a local market. At this level, you can run 2–3 ad variations and reach a meaningful audience. $1,000–$2,000/month gives you more flexibility to test audiences and scale what works.
Both platforms together: If you're running both, $1,500–$3,000/month in combined ad spend is a realistic minimum to get legitimate data from both channels and generate a steady flow of leads.
The Revenue-Percentage Rule (and Its Limits)
The U.S. Small Business Administration recommends 7–8% of gross revenue for marketing for businesses under $5 million in annual revenue. Of that, paid digital advertising typically represents 2–4% of total revenue.
This translates to:
- $500,000/year in revenue → $10,000–$20,000/year in total marketing → $10,000–$20,000 on digital ads (if that's your primary channel)
- $250,000/year in revenue → $5,000–$10,000/year → roughly $400–$800/month
That's useful context, but it has a critical flaw: it assumes your business is already at its target revenue level. A business trying to grow from $250,000 to $500,000 might need to spend more aggressively to get there, and then pull back once revenue supports the organic and referral channels that don't require ongoing ad spend.
Growth-stage businesses should think of advertising as an investment with an expected return, not just a percentage of existing revenue. If ads produce $3 for every $1 spent, spending 10–15% of revenue on ads to grow faster is a rational decision.
What Happens If You Spend Too Little
There's a threshold below which digital advertising doesn't generate enough data to be optimized. Spending $150/month on Google Ads, for example, produces maybe 15–20 clicks. At a 3% conversion rate, that's less than one lead per month. You can't learn anything from that, and you can't adjust what you can't measure.
The mistake many small businesses make is treating advertising like a cost to minimize rather than a channel to optimize. Small budgets produce small results. The data you need to improve the campaigns doesn't accumulate fast enough. The business concludes "ads don't work" and stops.
What actually happened: the budget was too small to get past the learning phase.
If your budget is genuinely limited, it's better to concentrate it on one platform and one campaign, do it well, and expand once you've validated the model, rather than spreading $200/month across three platforms and generating noise on all of them.
Thinking About Leads and Revenue, Not Spend
The better question isn't "what percentage of revenue should I spend on ads?", it's "how many new customers do I need per month, and what's the most cost-effective way to get them?"
If you need 10 new customers per month and your cost per acquired customer is $350, you need $3,500/month in ad spend. If your cost per acquired customer is $150, you need $1,500/month. The ad spend target follows from the business target.
This is why lead generation strategy and advertising management are intertwined. Running ads without a clear lead-to-customer path, a landing page that converts, a follow-up process that closes, a CRM that tracks it, means spending money that can't be measured or improved.
Practical Starting Points by Business Type
Trades and home services (plumber, electrician, HVAC, landscaping): Start with Google Ads. Budget $1,000–$2,000/month in ad spend. These searches have high intent and high ticket sizes that support the cost per click.
Restaurants and retail: Start with Meta Ads. Budget $500–$1,500/month. Visual creative, local audience targeting, and event promotion work well here.
Professional services (accountant, attorney, consultant): Google Ads for intent-based search. $1,000–$3,000/month depending on competition. High customer value justifies higher cost per lead.
E-commerce or product businesses: Meta Ads for discovery and retargeting; Google Shopping for high-intent searches. Combined budget of $1,500–$5,000/month to build meaningful reach.
In all cases: measure cost per lead, track it to cost per customer, and adjust spend and strategy based on what the numbers actually show.
Frequently Asked Questions
What is a good ROI for digital advertising?
A common benchmark is 4:1, four dollars in revenue for every dollar spent on ads. Efficient local campaigns often produce 3:1. Mature, optimized campaigns can hit 5:1 or higher. The right benchmark depends on your gross margins: a high-margin business can sustain a lower ratio than a low-margin one. The real question is whether your cost per acquired customer is below what a customer is worth.
How do I know if my ads are working?
Track cost per lead and cost per acquired customer, not impressions or clicks. Set up conversion tracking so your ad platform knows when someone calls, submits a form, or makes a purchase after seeing an ad. If cost per customer is below your target acquisition cost (based on lifetime value), the ads are working. If it's above, the landing page, ad copy, targeting, or follow-up process needs work.
Should I start with a small ad budget?
Yes, but not too small. Under $500/month on Google Ads often doesn't generate enough data to optimize. On Meta, $300–500/month can test creative and targeting in a local market. Start lean, validate your cost per lead, then scale what's working. Starting large before validating the campaign is as risky as starting so small you can't generate useful data.
What percentage of revenue should a small business spend on marketing?
The SBA recommends 7–8% of gross revenue for businesses under $5M in annual sales, with digital advertising typically representing 2–4% of that. Growth-stage businesses often need to invest more aggressively. The better question is whether your advertising produces a positive return on investment, if each dollar spent brings back $3–$4 in revenue, spending more makes sense regardless of the percentage rule.