Five frameworks for splitting ad budget: the 70/20/10 rule, marginal ROAS allocation, funnel-based budgeting, the portfolio model, and growth-stage allocation. Plus how to choose the right one and common allocation mistakes.
Framework 1: The 70/20/10 Rule
This is the simplest framework and a good starting point if you are unsure where to allocate. Split your budget like this:
- 70% goes to proven campaigns and channels. These are your known performers: campaigns that have been running for 3+ months with consistent ROAS above your target. This is your revenue engine. Do not experiment here.
- 20% goes to scaling and expanding proven approaches. New keyword sets on Google, new audiences on Meta, or new product categories in existing campaign types. Higher risk than your core 70%, but based on data that suggests it should work.
- 10% goes to experiments. New channels (TikTok, Pinterest), new campaign types (Demand Gen, video), or new creative formats. This is your R&D budget. Most experiments will not outperform your core campaigns, but the ones that do become tomorrow's 70%.
The 70/20/10 rule works because it protects your revenue while still investing in growth. The mistake most brands make is putting 100% into proven campaigns and never testing. That works until your proven campaigns start declining, and you have nothing ready to replace them.
Framework 2: Marginal ROAS Allocation
This is the most mathematically rigorous approach. It allocates budget to equalize marginal ROAS across all campaigns and channels. In plain English: put each additional dollar where it generates the most return.
Here is how it works. For each campaign, calculate the marginal ROAS (the return on the last dollar spent, not the average). Then rank all campaigns by marginal ROAS. Shift budget from campaigns with low marginal ROAS to campaigns with high marginal ROAS until they equalize.
Example: Your Google branded search has a marginal ROAS of 12x (saturated, limited by demand). Your Meta prospecting has a marginal ROAS of 2.5x. Your Google Shopping has a marginal ROAS of 4x. You should shift budget from branded search (where you can not spend more anyway) and potentially from Meta prospecting toward Google Shopping.
The downside: this framework is reactive and can underinvest in top-of-funnel channels that have low direct ROAS but feed your high-ROAS retargeting and branded campaigns. Use it as a guide, not gospel.
Framework 3: Funnel-Based Budgeting
This framework allocates budget by funnel stage rather than by platform. It works well for brands that run campaigns across multiple platforms and want to control how much goes to each stage of the customer journey.
- Bottom of funnel (40-50%): Branded search, retargeting, cart abandonment emails, and remarketing. These convert at the highest rate and should get the largest share because they close existing demand.
- Middle of funnel (25-35%): Non-branded search, Shopping/PMax, interest-based Meta prospecting. These reach people who are actively shopping or considering a purchase. Moderate conversion rates, larger addressable audience.
- Top of funnel (15-25%): Broad Meta prospecting, TikTok awareness, video campaigns, Demand Gen. These reach people who do not know you yet. Low direct conversion rates, but they fill your middle and bottom funnel over time.
The key insight: if you only invest in bottom-funnel campaigns, your retargeting audiences shrink over time because nobody new is entering the funnel. You need top-of-funnel spend to keep the pipeline full, even though its direct ROAS is lower.
Framework 4: The Portfolio Model
Borrowed from investment management, the portfolio model treats each campaign or channel like a financial asset with an expected return and a risk level. You build a "portfolio" that balances return and risk.
- Low-risk, high-return (bonds): Branded search, remarketing. Consistent, reliable, limited growth potential. Allocate enough to capture all available demand.
- Medium-risk, medium-return (blue chips): Non-branded search, Shopping, established Meta campaigns. Proven but with some variability. Allocate the bulk of your growth budget here.
- High-risk, variable-return (growth stocks): New channels, new creative formats, new markets. Some will fail, some will deliver outsized returns. Allocate a small percentage and evaluate quarterly.
This framework is especially useful for PPC managers who need to communicate budget allocation to executives or clients. The financial analogy makes the risk-return trade-offs intuitive.
Framework 5: Growth-Stage Allocation
Different stages of business growth require different allocation strategies. This framework adjusts based on where your ecommerce business is.
Launch stage ($0-$5K/month ad spend): Focus 80-90% on one platform (usually Google). Learn what works. Do not split budget across 3 channels when you barely have enough for one. Prove profitability on a single channel before expanding.
Growth stage ($5K-$25K/month): Expand to a second platform (usually Meta). Split roughly 60/40 between primary and secondary channels. Start building retargeting audiences from cross-platform traffic. This is where the signals for scaling become most important.
Scale stage ($25K-$100K/month): Three or more channels. 40/35/15/10 split (primary/secondary/tertiary/experimental). At this level, you should be measuring blended ROAS across all channels, not channel-level ROAS in isolation.
Mature stage ($100K+/month): Allocation is highly data-driven, based on marginal ROAS and incrementality testing. Most budget goes to proven performers with a dedicated 10-15% testing budget for new initiatives. See our scaling benchmarks for detailed numbers at each stage.
How to Choose the Right Framework
Not sure which framework fits? Here are some guidelines:
- New to multi-channel advertising? Start with the 70/20/10 rule. It is simple and hard to get seriously wrong.
- Data-rich and analytically inclined? Use marginal ROAS allocation. It requires more tracking and analysis but produces the most efficient allocation.
- Running campaigns across 3+ platforms? Funnel-based budgeting helps you think about the customer journey rather than platform-level metrics.
- Presenting to stakeholders? The portfolio model gives you a clear framework for justifying risk and return trade-offs.
- Growing fast and need a stage-appropriate plan? Growth-stage allocation tells you what to focus on right now.
Honestly, most brands blend two or three of these. You might use growth-stage allocation to set the overall split, then use marginal ROAS within each stage to decide exactly which campaigns get more or less budget.
Common Budget Allocation Mistakes
- Allocating by platform preference, not data. "We are a Meta-first brand" is a strategy. "We put 70% on Meta because our CEO likes Instagram" is not. Let the numbers guide allocation.
- Never rebalancing. Setting a budget split in January and not reviewing it until December. Channel performance shifts seasonally and with market conditions. Review monthly, adjust quarterly.
- Cutting top-of-funnel when bottom-funnel ROAS dips. Bottom-funnel performance depends on top-funnel investment. Cutting awareness campaigns to "save budget" often causes retargeting performance to decline 4-6 weeks later as the funnel dries up.
- Spreading too thin. $10K/month split across 5 channels means $2K per channel. That is probably not enough for any of them to produce meaningful data or results. Concentrate, then expand.
- Treating allocation as permanent. The right allocation changes as you scale, as channels mature, and as competition shifts. What worked at $10K/month will not work at $50K/month. Revisit your framework as your spend grows.
Frequently Asked Questions
Most ecommerce brands spend 10-20% of revenue on advertising. Early-stage brands investing in growth might spend 25-30%. Established brands with strong organic traffic might spend 8-12%. The right number depends on your margins, growth goals, and how much of your revenue comes from paid vs organic channels.
Review allocation monthly and make adjustments quarterly. Monthly reviews catch underperforming channels early. Quarterly adjustments prevent constant rebalancing that disrupts campaign learning. The exception is seasonal periods where you should shift budget more aggressively toward proven channels.
Almost never. Equal allocation ignores that each channel has different efficiency levels and different addressable market sizes. Allocate based on marginal ROAS: put more money where the next dollar generates the most return, not where the average return is highest.
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