VND 300 million approved, VND 80 million spent
At the start of the month, the brand owner approves VND 300 million for advertising, expecting a significant boost in revenue. At the end of the month, the report shows that only about VND 80 million was spent.
Suspicion usually falls first on the campaign manager: maybe they weren’t doing enough. Sometimes that’s true. But the more common cause is that the budget has hit a pre-existing ceiling, one that exists regardless of who is running the ads.
Advertising doesn’t create search demand
Search ads on the marketplaces only show when someone types in a relevant keyword. If nobody searches, the ad has no chance to show, and the budget cannot be deployed.
The maximum you can spend efficiently, given the market’s actual demand, is what we call the demand ceiling. For search ads, you can estimate this ceiling with a simple formula:
Search spend ceiling ≈ monthly searches × impression share won × click-through rate (CTR) × cost per click (CPC)
| Component | Value |
|---|---|
| Monthly searches for the category’s keyword set | 400,000 |
| Ad impression share won | 60% |
| Click-through rate | 4% |
| Cost per click | VND 3,500 |
| Monthly search spend ceiling | About VND 34 million |
Illustrative example, hypothetical figures.
Back to the example: if you approve VND 300 million for search ads, most of that money cannot be spent efficiently. The problem isn’t a lack of effort; it’s that the market doesn’t have enough people searching.
Self-optimizing ads also throttle themselves
Beyond search ads, every marketplace offers ad formats that show products to people who aren’t actively searching, along with automated modes that optimize toward a ROAS target set by the advertiser. The algorithm looks for the people most likely to convert and shows the ad to them.
When it can no longer generate additional orders while maintaining the target ROAS, the system automatically throttles delivery and spends less than the allocated budget, because spending more would drag ROAS below target. That is the algorithm protecting efficiency, not a system error.
So an “unspent budget” is often a signal: the pool of buyers available at that level of efficiency has largely been exhausted.
What forcing the full spend costs you
There is always a way to spend the whole budget, but each one comes at a cost:
- Lower the target ROAS. The system extends delivery to people who are less likely to buy. Spend goes up, but efficiency goes down.
- Open up broader, less relevant keywords. Clicks come from people who aren’t really looking for this product, so the conversion rate drops.
- Raise bids. The shop pays more for the same clicks, from the same people.
All three are sliding along the saturation curve: you manage to spend more money, but each additional dong brings back less. The portion of budget that is forced out usually has a marginal ROAS below break-even.
Spending the whole budget is not the goal
An approved budget should be read as a cap on spending, not a quota you are required to hit. The right measure isn’t “what percentage of the budget did we spend”, but “did the budget we spent earn a marginal ROAS above the break-even threshold”.
Unspent budget is money that hasn’t been burned.
Raising the demand ceiling
The demand ceiling can absolutely be raised, but advertising isn’t the only tool for the job.
- Increase branded search volume. Searches for your brand name are a source of demand that only grows as brand awareness grows. That is the work of the asset layer in the three-layer map.
- Broaden the prospect pool. Content, KOCs (key opinion consumers) and livestreams put the product in front of people who have never searched for it, and gradually nurture them into people who will actively search for it in the months that follow.
- Price sets how wide the pool can be. The higher your price relative to the market, the narrower the group willing to buy. For a brand that can’t cut its price, widening the pool is tightly bound to where it sits on the brand-price matrix.
- Capitalize on seasonality. The demand ceiling rises during the category’s peak season and major sale events, then drops afterward. Budgets should flex with this rhythm, rather than being fixed at one number for every month.
Estimate the demand ceiling for your own shop
- List 10-20 keywords that buyers actually use to search for the product, including your brand name.
- Get the monthly searches for each keyword from the keyword data the marketplace provides. If the marketplace doesn’t show this number, use the keyword’s actual impressions from periods when it ran unconstrained by budget.
- Multiply by impression share, click-through rate and cost per click, using your shop’s current figures.
- Compare the result with the budget you have approved for search ads.
This is only a rough estimate. Ads shown to people who aren’t actively searching can spend some additional amount on top of this figure. The point isn’t a perfectly precise number; it’s knowing how far your approved budget sits from the ceiling.
Conclusion
In most cases, an unspent budget does not mean your ads are underperforming. It reflects a reality: existing demand has been mostly captured at an acceptable level of efficiency. To spend more and stay profitable, you need to expand demand, and that is the work of the foundational layers that sit beneath advertising.