The most important affiliate marketing key performance indicators (KPIs) are conversion rate, average order value, cost per acquisition, return on ad spend, and the share of affiliates actively driving sales. KPIs are the metrics that show whether a campaign strategy is working against an established goal, and in affiliate marketing they also show which partners are driving real value.
In the programs we manage, the KPIs that change budget decisions are the ones tied to partner quality and incremental sales, and the channel’s growth is raising the stakes for measuring them well. EMARKETER’s 2026 affiliate marketing FAQ projects US affiliate spending will reach $13.81 billion in 2026, up 11.3% from 2025, yet 43.2% of marketers either leave affiliate data out of campaign planning or add it only after budgets are set. Benchmarks are moving too: impact.com’s 2025 affiliate benchmark found that average order value across 2,368 North American retail brands rose from $118 to $123, while conversion rates fell 6% year over year.
Below are the 18 KPIs worth tracking, the formula for each, the benchmarks that exist for them, and how to use them to improve your program.
Key Takeaways
- Affiliate marketing KPIs fall into three groups: engagement, conversion, and affiliate-level performance, and the right mix depends on whether your goal is sales or awareness.
- Affiliate-specific KPIs like earnings per click, cost of sale, reversal rate, and incrementality show what generic marketing metrics miss: which partners actually add value.
- Published benchmarks give useful context, but your own program’s baseline by partner type is the most reliable comparison.
- Tracking a few KPIs tied to your goals and reviewing them at least monthly leads to faster, clearer decisions than monitoring every metric.
Which affiliate marketing KPIs should you track?
The KPIs you should track depend on your campaign goal. If your goal is sales, focus on conversion rate, average order value, and return on ad spend. If your goal is brand awareness, monitor clicks, impressions, and click-through rate. Every program should also track at least one affiliate-level KPI, such as the share of sale-active affiliates, because overall totals can hide which marketing partners drive the most value.
A single KPI can tell the wrong story on its own. impact.com’s 2025 benchmark showed shoppers buying less often but spending more per order, so a program judged only on conversion rate could look like it’s slipping while revenue per order is actually growing.
18 affiliate marketing KPIs and how to calculate them
Generic marketing metrics show whether a campaign is working, and affiliate KPIs also show which partners are responsible for it. impact.com’s 2025 benchmark makes the gap visible: network partners generated 45% of clicks but only 18% of transactions, while loyalty and rewards partners turned 15% of clicks into 50% of transactions.
The 18 KPIs below are grouped into engagement, conversion, and affiliate-level metrics. The first two groups tell you how the program performs overall, and the third shows where those partner differences come from.
Engagement KPIs
Clicks. How many people click on affiliate links. Formula: Total clicks on affiliate links. Benchmark: Up 2% year over year in North American retail, 45% in November (impact.com, 2025). Use it for awareness and traffic goals.
Impressions. How many times affiliate content is shown to users. Formula: Total times content is displayed. Benchmark against your own baseline by partner type. Use it for awareness goals and content partners.
Click-through rate (CTR). How often someone clicks a link after seeing it. Formula: Clicks / Impressions x 100. Benchmark against your own baseline by partner type. Use it for judging creative and placement quality.
Conversion KPIs
Total sales or conversions. How many sales or conversions the program generated. Formula: Total affiliate-driven conversions. Benchmark: Transactions down 5% year over year in North American retail (impact.com, 2025). Use it for every program, as a baseline.
Conversion rate (CR). How many visitors from affiliate links made a purchase. Formula: Total conversions / Total visitors x 100. Benchmark: Down 6% year over year overall, up 8% for influencers and 25% for technology partners (impact.com, 2025). Use it for sales goals and partner quality.
New vs. returning customers. How many affiliate customers are first-time buyers. Formula: New customers / Total customers x 100. Benchmark against your own baseline by partner type. Use it for acquisition goals.
Average order value (AOV). How much the average buyer spends per transaction. Formula: Total revenue / Total orders. Benchmark: $123 for North American retail (impact.com, 2025). Use it for sales goals and partner mix.
Customer lifetime value (CLV). Total revenue expected from a customer over time. Formula: Average revenue per user (ARPU) x Customer lifespan. Benchmark against your own baseline by partner type. Use it for deciding where to invest commission.
Return on ad spend (ROAS). Revenue generated for every dollar of affiliate cost. Formula: Affiliate revenue / (Commissions + Fees). Benchmark: $11 per $1 in retail, $19 in travel (Performance Marketing Association, 2025). Use it for program efficiency.
Return on investment (ROI). Profit generated compared to total program cost. Formula: Net profit / Total cost x 100. Benchmark against your own baseline by partner type. Use it for budget conversations.
Cost per acquisition (CPA). How much each new customer costs. Formula: Total program cost / New customers. Benchmark against your own baseline by partner type. Use it for comparing affiliate with other channels.
Reversal or return rate. Share of affiliate orders later reversed, canceled, or returned. Formula: Reversed orders / Total affiliate orders x 100. Benchmark against your own baseline by partner type. Use it for spotting low-quality traffic.
Affiliate KPIs
Earnings per click (EPC). Revenue generated per affiliate click, also called revenue per click. Formula: Affiliate revenue / Clicks. Benchmark against your own baseline by partner type. Use it for comparing partners of different sizes.
Percentage of click-active affiliates. Share of affiliates driving clicks. Formula: Affiliates with clicks / Total affiliates x 100. Benchmark against your own baseline by partner type. Use it for program health and recruitment.
Percentage of sale-active affiliates. Share of affiliates driving sales. Formula: Affiliates with sales / Total affiliates x 100. Benchmark against your own baseline by partner type. Use it for program health and activation.
Revenue by affiliate. Each affiliate’s share of total program revenue. Formula: Affiliate revenue / Total program revenue x 100. Benchmark against your own baseline by partner type. Use it for spotting dependence on a few partners.
Cost of sale or commission rate. What you pay partners as a share of the revenue they drive. Formula: (Commissions + Fees) / Affiliate revenue x 100. Benchmark: Commissions are 86% of total brand spend in the channel (impact.com, 2025). Use it for margin and commission strategy.
Incrementality. Share of affiliate sales that would not have happened without the partner. Formula: Test group conversions minus control group conversions, divided by test group conversions. Benchmark against your own baseline by partner type. Use it for deciding which partners deserve more budget.
How do you use KPIs to optimize an affiliate program?
You use KPIs to decide where to invest, which partners to grow, and which to rework. If one or two partners are generating the highest number of sales, extend or expand those partnerships. If your goal is traffic and affiliate content on one social platform drives considerable volume, prioritize spend on that platform. If a partner has strong clicks but a high reversal rate, review the traffic quality before raising its commission.
We rebuilt DAZN’s US affiliate program around three KPIs: cost per acquisition, publisher activation, and ROI. By adjusting CPA structures, optimizing payouts across partners, and focusing on activation, we recruited 124+ new publishers in three months with a 78% publisher activation rate and delivered a 7.2x ROI. Our private AI platform, Prism, helps our teams track these KPIs across partners and turn them into program decisions, part of how we run affiliate partnership management for brands around the world.
Benchmarks tell you whether a KPI is healthy
A KPI only becomes useful once you know what good looks like. The Performance Marketing Association’s 2025 Industry Study found that affiliate marketing returns $11 for every $1 invested in retail and $19 in travel, with department stores reaching $21. impact.com’s 2025 benchmark puts average order value for North American retail brands at $123 and shows commissions make up 86% of total brand spend in the channel, a useful reference point when you evaluate your own cost of sale.
Published benchmarks rarely give absolute figures for conversion rate, earnings per click, or reversal rate, and the trend data that does exist varies widely by partner. In impact.com’s 2025 data, conversion rates fell 6% across retail overall while rising 25% for technology partners. For those KPIs, the most reliable benchmark is your own program’s history, broken out by partner type.
Track fewer KPIs and act on them faster
Tracking every metric at once slows decisions down. Monitor the KPIs most closely aligned with your campaign goals, review them on a set schedule, and look for opportunities to improve performance and scale your affiliate program along the way.
Those KPIs also need a place in budget planning, where affiliate often gets lost. EMARKETER reports that 27.3% of marketers using marketing mix modeling fold affiliate into a general performance bucket, which makes it hard to see what the channel contributes on its own. Reporting affiliate KPIs separately, with ROAS and ROI tied to revenue, gives the channel a clear place in those conversations.
To see how an agency puts these KPIs to work day to day, read about what an affiliate program management agency does. If you want help choosing and tracking the right KPIs for your program, contact us to get started.
Frequently asked questions
How do you determine which KPIs matter most in affiliate marketing?
Choosing the most important KPIs depends on campaign goals. If you’re just getting started, focus on conversion rate, click-through rate, and the share of sale-active affiliates to gauge whether the program and its partners are working.
What’s the best way to track multiple affiliate marketing KPIs?
Tracking multiple affiliate marketing KPIs often involves a combination of platforms, such as your affiliate network or tracking platform for conversions and Google Analytics for traffic. Our private AI platform, Prism, can generate custom reports based on the KPIs you identify at the start of your campaign.
How often should you review affiliate marketing KPIs?
As a general rule of thumb, review metrics at least once a month for long-term campaigns, and more frequently for short-term campaigns or seasonal peaks.
What is a good conversion rate for affiliate marketing?
A good affiliate conversion rate depends on your vertical, price point, and partner mix, so the strongest benchmark is your own program’s baseline by partner type. The partners in your mix shape that rate: impact.com’s 2025 benchmark found conversion rates fell 6% across North American retail brands overall, but rose 8% for influencer partners and 25% for technology partners.
What’s the difference between ROAS and ROI in affiliate marketing?
Return on ad spend (ROAS) measures revenue against affiliate costs, calculated as affiliate revenue divided by commissions plus fees. Return on investment (ROI) measures profit against total program cost, so it accounts for product margins and other expenses. A program can show a strong ROAS and a weaker ROI if commissions are paid on low-margin products.
