Do not let a generic percentage make a specific investment decision
Search results are full of marketing budgets expressed as a percentage of revenue. The ranges vary because the businesses behind them vary. A mature professional-services firm, a new subscription company and a local home-service business can have the same turnover but radically different margin, customer value, sales speed and capacity.
Use a revenue percentage as an affordability warning light, not as the answer. Current Australian Government guidance says a marketing budget should connect spending to marketing goals and be reviewed as the business and its customers change. That is a sound governance principle, but it still leaves the owner with the important question: what should we fund next? Business.gov.au marketing-plan guidance.
My verdict is: set paid advertising from the commercial outcome backwards, then choose the next budget state from the quality of your evidence. Platform forecasts can test whether a plan is plausible. They cannot decide what a customer is worth, how much risk the business should carry or whether the team can serve more demand.
The Paid Growth Capital Gate: prepare, validate, repair or scale
Before discussing a number, place the business in one of four states. This prevents the same budget conversation being applied to businesses with entirely different problems.
Foundations are not ready
Customer economics, offer, measurement or sales ownership is unclear. Protect cash and fix the missing foundation before buying more demand.
One uncertainty needs an answer
Use a capped test to learn whether a defined audience and offer can create a qualified business outcome at an acceptable cost.
Spend exists but value leaks
Hold the total budget while improving buyer fit, conversion, lead progression or measurement. More media is not the first move.
The next increment has a case
Increase in controlled steps when marginal customer outcomes remain economic and the business can absorb additional demand.
A percentage cannot tell you which state you are in. Nor can a platform recommendation. If the business is still in Prepare, use the paid-advertising readiness test. If it is in Repair, first determine whether growth is available without increasing the total marketing budget.
Build the number with the Revenue-Backed Budget Model
Once the capital state is clear, work through five owner-level decisions. Start outside the advertising platform because the platform does not know your gross profit, cash exposure, sales conversion or fulfilment limit.
1. Translate the growth goal into suitable customers
Start with the commercial gap, not impressions or clicks. Define the additional customers, qualified opportunities or contribution the business needs. Then use observed sales data to work backwards. If the goal requires more customers than sales or delivery can handle, the advertising budget is not the current constraint.
2. Set an allowable total acquisition cost
Customer acquisition cost is the complete cost required to win a customer, not just media spend. The allowable amount must leave enough gross profit to deliver the work, cover operating costs and meet the business's required payback. Separate media, management, creative, landing pages and measurement for transparency, but include them in the investment case.
This is a boundary for planning, not permission to spend the full amount.
3. Fund the evidence threshold, not an arbitrary month
A very small test can be wasteful if it never produces enough qualified outcomes to distinguish a weak proposition from normal variation. A large test can be reckless when the offer and measurement are unproven. Define one decision in advance: for example, can this audience and offer create sales-qualified opportunities within the economic limit? The budget must be capable of answering it.
4. Match evaluation to the buying cycle
Recent results are often incomplete because customers take time to convert. Google Ads provides conversion-lag reporting to show how long clicks can take to produce recorded conversions. Use the real lag between enquiry, qualified opportunity and customer—not a convenient seven-day reporting window—before changing the budget. Google Ads conversion-lag guidance.
5. Put a capacity trigger beside the cost trigger
A campaign can be efficient and still be wrong for the business if leads are unanswered, stock is constrained or delivery is full. Decide what happens as demand approaches capacity: narrow targeting, prioritise higher-value demand, improve follow-up or delay the next increase. If there is no dependable sales receiver, review whether paid ads should run before a sales team is in place.
An illustrative budget calculation
This example explains the logic. It is not client performance, a market benchmark or a recommended minimum. Replace every input with verified finance, sales and customer data.
If the business needs 20 qualified leads to evaluate the offer, the media planning figure would be £3,000. That is not the total programme budget and it is not a promise of two customers. Management, creative, landing-page and measurement costs still belong in the full acquisition case; conversion lag, lost leads, cash timing and capacity still affect the decision.
The calculation becomes stronger as evidence improves. I use a simple Budget Confidence Ladder:
- Assumption: customer value and conversion rates are estimates. Keep exposure tightly capped.
- Qualified demand: the channel produces suitable enquiries, but customer outcomes are immature. Hold while the sales cycle completes.
- Customer evidence: outcomes and total acquisition cost are verified. Consider a controlled increase.
- Marginal evidence: the most recent increment still creates economic customers without breaking capacity. Continue or reallocate deliberately.
Choose the next budget decision from the evidence
| What the owner sees | Capital state | Next decision | Avoid |
|---|---|---|---|
| Offer, economics or sales ownership is unclear | Prepare | Fix the commercial foundation and measurement | Buying a token volume of clicks |
| New audience, offer or market with a clear hypothesis | Validate | Fund one decision-sized, cash-capped test | Launching every channel at once |
| Leads arrive but quality or sales progression is weak | Repair | Hold spend and remove the value leak | Optimising for cheaper forms |
| Verified customers remain within the economic limit | Scale | Increase in measured increments | A fixed percentage uplift |
| The latest increment costs more or strains capacity | Hold or reallocate | Protect the strongest demand and reassess the constraint | Defending last month's budget |
When the evidence supports Scale, use the separate guide on when to increase an advertising budget. When results or governance no longer support the current provider, use the provider-change evidence test before moving accounts or data.
Review the next dollar, not only the average result
Average performance can hide a weakening next increment. A campaign may still look profitable overall even though the latest budget increase produced customers at an unacceptable cost. Review the additional outcome created by the additional spend, alongside the blended result.
For established Google Ads campaigns, Performance Planner can model how changes to bids and budgets might affect key metrics. Google says its forecasts are refreshed daily using recent data and adjusted for seasonality. Treat those forecasts as scenario inputs, not guarantees, and reconcile them with verified customer outcomes. Google Ads Performance Planner guidance.
Also plan for billing behaviour. For most Google Ads campaigns, an average daily budget may spend up to twice that amount on an individual day while the monthly spending limit is generally 30.4 times the average daily budget. That operating detail matters to cash control even though it does not determine the economically correct budget. Google Ads average daily budget guidance.
Use a review window that covers the buying cycle and answer five questions:
- Outcome: did spend create suitable customers, qualified pipeline or revenue?
- Economics: is the complete acquisition cost inside the agreed limit?
- Evidence: are recent results mature and measurement reliable?
- Marginal return: did the latest increment remain economic?
- Capacity: can sales and delivery support another increment?
A responsible budget is a controlled allocation of growth capital. It changes when customer economics, evidence or capacity changes—not because a generic percentage, competitor claim or platform prompt says it should. For implementation options, review my Google Ads and Meta Ads services. For the wider operating model, see the growth partnership, case-study evidence, evidence standards and how I work directly with clients.
Sources and evidence notes
Sources were checked on 6 September 2026. The Paid Growth Capital Gate, Revenue-Backed Budget Model, Budget Confidence Ladder and decision matrix are original ThomPerformance analysis. Search priority is qualitative: no search volume, universal budget percentage, channel minimum, conversion benchmark or performance result is claimed.
Frequently asked questions
What percentage of revenue should a business spend on advertising?
There is no universal percentage that works across margins, growth stages, sales cycles and business models. A revenue percentage can be a board-level affordability check, but it should not set the operating budget. Build that budget from customer economics, the evidence required for a decision, cash exposure and the business's capacity to convert demand.
What is a reasonable test budget for paid advertising?
A reasonable test budget is the smallest amount likely to produce enough qualified outcomes to answer one commercial question without putting cash flow at risk. It depends on market costs, the buying cycle and the conversion path. A number that produces many clicks but too few qualified outcomes is not a cheaper test; it is an inconclusive one.
Should fees, creative and tracking be included in the advertising budget?
Yes. Show media separately so platform spend stays transparent, but include management, creative, landing pages, measurement and relevant sales costs in the complete investment case. A campaign can appear viable at media level while the total cost of acquiring and converting customers is above the business's economic limit.
How long should a business test paid advertising before judging it?
Use the real time between an advertising interaction and a qualified lead, sale or customer outcome. Review delivery and obvious errors early, but do not judge a long-sales-cycle campaign using only the first week's leads. Set the evaluation window and stop conditions before launch, then account for conversion lag when reading recent results.
When should an owner increase, hold or reduce the budget?
Increase it when verified customer outcomes remain inside the allowable acquisition cost and sales or fulfilment can absorb more demand. Hold it while evidence is immature or measurement is being repaired. Reduce, narrow or pause it when customer economics fail, lead quality deteriorates, capacity is constrained or the next increment has no credible business case.
Make the next budget increment earn its case
The right paid-advertising budget connects a growth goal to customer economics, funds enough evidence for a decision and respects the business's capacity to sell and deliver. Start with the appropriate capital state, protect cash while outcomes mature, and increase spend only when the next increment still creates supportable value.