How to Choose a PPC Agency: What 818 Case Studies Show

Most guides to choosing a PPC agency tell you to check certifications, ask about reporting and look at case studies. They rarely say what a PPC case study should contain, or which numbers are missing from most of them.

This guide does. Each step below comes from 818 PPC case studies published by 48 agencies and indexed in OpenServed's directory. We counted what agencies report, what they leave out, and what a typical published result looks like, so every piece of advice here comes with evidence.

Data as of October 2026. The full numbers are in PPC Statistics 2026.

The short answer

1. Know what a realistic result looks like. The median published PPC case study reports a 39% cut in cost per acquisition and an 89% increase in conversions or leads.
2. Look for results in the metric you care about. Online stores should see revenue and ROAS; lead-driven businesses should see cost per lead.
3. Check that growth and cost are shown together. Only 32% of PPC case studies report both.
4. Ask for the spend, the starting cost and the timeframe. Fewer than 5% of case studies mention ad spend.
5. Ask what counts as a conversion. 71% of conversion results don't say.
6. Ask which channel and campaign produced the result. 75% of PPC case studies bundle other services.
7. Ask whether the client confirmed it. Only 3.3% of PPC case studies are Client-verified.

1. Know what a realistic result looks like

The median PPC case study reports a 39% cut in cost per acquisition or lead. Among the 197 case studies that state a reduction, half fall between 24% and 59%, and six in ten fall between 20% and 59%.

On volume, the typical published result is close to a doubling. The median reported increase is 89% for conversions or leads (306 case studies) and 105% for revenue (203 case studies).

These are the wins. Agencies publish the campaigns that went well, so a typical account is likely to land lower.

Cost cuts are about the same at every company size. The median cut is 40% for small businesses, 37% for medium, 34% for large and 38% for enterprise. Volume gains shrink as clients get bigger: the median gain in conversions or leads is 103% for small businesses and 65% for enterprises.

Volume gains vary by industry. Median reported gain in conversions or leads:

• Industrial & Manufacturing: 143%
• Home, Property & Local Services: 100%
• Healthcare & Wellness: 93%
• Education & Nonprofit: 87%
• Financial Services: 84%
• Retail & Ecommerce: 78%
• Software & Technology: 75%

What to do: ask an agency what result it expects for you and what that estimate is based on. A range near these figures, tied to accounts like yours, is a good sign. Be wary of a guarantee, or of a promised cost cut far above 60% with no explanation.

2. Look for results in the metric you care about

PPC is proven in different numbers depending on what you sell. A revenue stat appears in 59% of retail and ecommerce PPC case studies and 56% of fashion ones. A cost per acquisition or lead stat appears in 50% of software and financial services case studies and 47% of healthcare ones, but only 8% of fashion ones.

ROAS is an ecommerce number. It appears in 23% of fashion case studies and 19% of retail ones, against 4% of software ones. Across all PPC case studies, only 11% report it.

A fifth of PPC case studies show neither growth nor cost. 20% report no conversions, leads, revenue, cost per acquisition or ROAS. They rely on clicks, traffic or results from another channel.

What to do: if you sell online, look for agencies whose case studies report revenue and ROAS. If you generate leads, look for cost per lead and lead volume. Clicks and click-through rate on their own don't show that an agency can deliver either.

3. Check that growth and cost are shown together

Only a third of PPC case studies show both. 71% report a growth result (conversions, leads or revenue) and 42% report a cost or return result (cost per acquisition, ROAS or ROI). Only 32% report the two together.

39% show growth with no cost beside it. More conversions can simply be bought with a bigger budget. Without a cost per acquisition or a ROAS, you can't tell whether the account got better or just bigger.

9% show cost or return with no growth beside it. Cost per acquisition also falls when an agency cuts spend down to the cheapest clicks. That can mean fewer customers, not more.

The complete result has both. Among the 135 case studies that state a cost cut and a conversion or lead gain together, the median is 37% lower cost and 100% more conversions or leads.

What to do: ask for conversions and cost per acquisition side by side, for the same period. One without the other is half a result.

4. Ask for the spend, the starting cost and the timeframe

Ad spend is almost never disclosed. Only 4.5% of PPC case studies mention ad spend or budget, and just 10 of the 818 give a dollar amount. Of the 91 that report ROAS, only 8 mention the spend behind it.

Actual costs are rare too. Only 3.5% state a cost per acquisition, lead or click in dollars, and only 2.6% show a before and an after number. The rest give a percentage.

Fewer than 2% say how long the work took. Only 14 state an engagement length, and only 18% mention any time period at all.

Check that the numbers are possible. Five case studies claim a cost reduction of more than 100%, which can't happen. A percentage with no dollar figures behind it is easy to get wrong.

What to do: for any result that matters to you, ask for the monthly ad spend, the cost per acquisition before and after in dollars, and the number of months it took. A 40% cut on $2,000 a month is a different job from a 40% cut on $200,000.

5. Ask what counts as a conversion

Most conversion results don't say what a conversion is. 28% of PPC case studies report conversions, and 71% of those stats say only "conversions". A conversion can be a sale, a form fill, a phone call or a newsletter sign-up, and they aren't worth the same.

Only 5% report lead quality. Just 39 case studies mention qualified leads, sales pipeline or new customers. The rest count every lead alike.

Only 2% separate branded from non-branded search. Clicks on your own brand name come from people who were already looking for you. They convert well and cost little, so including them flatters any result.

What to do: ask which actions were counted as conversions, how many became qualified leads or sales, and whether branded search is included. Ask to see non-branded results on their own.

6. Ask which channel and campaign produced the result

75% of PPC case studies bundle PPC with another service. SEO appears alongside in 41%, social media ads in 25% and web design in 14%. Only 25% are about PPC alone.

A third include results from another channel. 33% of PPC case studies contain at least one stat about organic search, social, email or another channel. Across all PPC case studies, 17.5% of the results listed are about a different channel.

Only 8% name the platform or campaign type. Few say whether a result came from Google search ads, shopping, display or video.

Bundles report bigger volume gains, with the same cost cuts. The median gain in conversions or leads is 74% where PPC is the only service and 101% where it is bundled. See SEO vs PPC.

What to do: if an agency shows bundled results, ask which channel produced each number. Cost per acquisition, click-through rate and ROAS belong to paid media; conversions and revenue may not.

7. Ask whether the client confirmed it

Only 3.3% of PPC case studies are Client-verified. 27 of the 818 carry OpenServed's Client-verified badge, meaning the named client confirmed the results. The other 96.7% are the agency's own account.

What to do: ask to speak with the client behind a case study that matters to you, or give more weight to results the client has confirmed. A reference call is a reasonable thing to ask for before you sign.

Questions to ask a PPC agency

Each question below comes from one of the seven steps. A good answer is specific; a warning sign is a number with nothing behind it.

1. What result should we expect, and what is that based on? A good answer is a range tied to accounts like yours, near typical published gains. A warning sign is a guarantee, or a promised cost cut far above 60%.
2. Can you show results in the metric we care about? A good answer is revenue and ROAS for online stores, or cost per lead for lead generation. A warning sign is only clicks, impressions or click-through rate.
3. Did cost go down while volume went up? A good answer shows conversions and cost per acquisition side by side. A warning sign is more conversions with no cost figure, or lower cost with no volume.
4. What was the ad spend, the starting cost and the time period? A good answer gives the spend, the cost before and after in dollars, and the months it took. A warning sign is a ROAS or a percentage with no spend and no dates.
5. What counts as a conversion? A good answer is a defined action, and how many became qualified leads or sales. A warning sign is "conversions up 200%" with no definition.
6. Which channel and campaign produced the result? A good answer separates paid search from SEO and social, and splits out branded search. A warning sign is one blended number across every channel.
7. Can we speak with the client, or is the result verified? A good answer is a reference call or a client-verified case study. A warning sign is no named client and no reference.

Red flags when hiring a PPC agency

• A guaranteed result. Published cost cuts have a median of 39% and a wide spread. Nobody can promise where your account will land.
• Growth with no cost. 39% of PPC case studies show more conversions, leads or revenue with no cost or return figure. An agency that can't show both hasn't shown the account improved.
• ROAS with no spend. Of the 91 case studies that report ROAS, 8 mention the spend behind it. A high ROAS on a small budget, or on branded search alone, says little.
• Results measured against a goal. 7% of PPC case studies include a result stated against a target or an industry average, not against where the account started. "Beat the goal by 40%" depends on who set the goal.
• Numbers that can't be right. Five case studies claim cost reductions above 100%. Check the arithmetic on anything that looks too good.
• One number for everything. If a result mixes paid search with SEO or social, the agency should be able to separate them.

One more thing to settle before you sign: get the agency's fee in writing, separate from your ad spend. Our data has no pricing, so we can't tell you what a fair fee is, but you should know exactly what you are paying the agency and what you are paying the ad platforms.

Find a PPC agency

OpenServed's PPC agency directory lists agencies by the case studies they have published, so you can check each of the steps above before you make contact. You can narrow it to your industry, such as SaaS, ecommerce or healthcare, or to your size, such as small business or enterprise. Look for the Client-verified badge on results the client has confirmed.

About the data

The figures in this guide come from the 818 case studies in OpenServed's directory that list PPC as a service, published by 48 agencies, as of October 2026. Results are as reported by each agency; only 27 have been confirmed by the client. Agencies publish their best work, so these numbers describe successful campaigns, not average ones. The full method is in PPC Statistics 2026.