Media Math 101
Every formula a junior media buyer, planner, or account manager needs — explained in plain English with links to free calculators.
CPM — Cost Per Mille
CPM is the price you pay for 1,000 ad impressions. It's the universal currency of display, video, social, and programmatic media buying. When someone says "a $10 CPM," they mean $10 for every thousand times the ad is shown.
To find your budget, flip the formula: Budget = (CPM × Impressions) ÷ 1,000. To find impressions: Impressions = (Budget ÷ CPM) × 1,000. Any two values give you the third.
When to use it: Use CPM when buying or evaluating awareness campaigns where the goal is eyeballs, not clicks. It's the standard for display, video pre-roll, CTV, audio, and most programmatic buys.
Open the CPM calculator →CPC — Cost Per Click
CPC measures how much each click costs. It's the default pricing model for search advertising and many social platforms. A lower CPC means you're driving traffic more efficiently.
CPC tells you cost efficiency, but not quality. A $0.50 CPC that drives no conversions is worse than a $3.00 CPC that converts at 10%. Always pair CPC with downstream metrics like CPA or ROAS.
When to use it: Use CPC when buying on platforms that charge per click (Google Ads, paid social) or when evaluating how efficiently a campaign drives site traffic.
Open the CPC calculator →CPA — Cost Per Acquisition
CPA is the cost of one conversion — a sale, a lead, a sign-up, whatever your campaign goal is. It's the metric that ties media spend directly to business outcomes.
CPA depends on both your media costs (CPM or CPC) and your conversion rate. You can lower CPA by reducing media costs, improving targeting, or optimizing the landing page experience.
When to use it: Use CPA when the campaign has a measurable conversion event. It's the go-to metric for performance marketing, lead gen, e-commerce, and app install campaigns.
Open the CPA calculator →CTR — Click-Through Rate
CTR is the percentage of impressions that resulted in a click. It measures how compelling your ad is — a higher CTR means more people found the creative or message interesting enough to act on.
Industry benchmarks vary wildly: display banners average 0.05–0.10%, while search ads often see 2–5%. Don't compare CTRs across channels — compare within the same format and placement.
When to use it: Use CTR to evaluate creative performance, A/B test ad variations, and diagnose whether low traffic is a creative problem (low CTR) or a scale problem (low impressions).
Open the CTR calculator →ROAS — Return on Ad Spend
ROAS tells you how many dollars of revenue you earned for every dollar spent on advertising. A 4× ROAS (or 400%, or "$4 return per $1") means $4 in revenue for every $1 of ad spend.
ROAS focuses on top-line revenue, not profit. A 4× ROAS sounds great until you realize the product margin is only 20% — then you're barely breaking even. That's why many teams also track ROI and profit margin.
When to use it: Use ROAS for e-commerce and direct-response campaigns where revenue is tracked. Express it as a multiple (4×), a percentage (400%), or a dollar return ($4) depending on your team's convention.
Open the ROAS calculator →ROI — Return on Investment
ROI measures profit relative to cost, expressed as a percentage. Unlike ROAS (which uses revenue), ROI subtracts costs first, so it reflects actual profit efficiency.
A 100% ROI means you doubled your money. A 0% ROI means you broke even. A negative ROI means you lost money. Include all costs — media, creative production, platform fees, agency fees — for an accurate picture.
When to use it: Use ROI when you need to account for all costs (not just media spend) and want to express returns as a profit percentage rather than a revenue multiple.
Open the ROI calculator →Reach & Frequency
Reach is the number of unique people who saw your ad. Frequency is how many times each person saw it, on average. Together they tell you how wide and how deep your campaign went.
Most awareness campaigns aim for a frequency of 3–7: enough for the message to register without becoming annoying. Too low (under 2) and people may not remember the ad; too high (over 10) and you risk ad fatigue and wasted spend.
When to use it: Use reach and frequency when planning brand awareness or upper-funnel campaigns, especially in TV, OOH, audio, or high-reach digital buys.
Open the Reach & Frequency calculator →GRP & TRP — Gross / Target Rating Points
GRP (Gross Rating Points) is the standard unit of TV and radio media weight. It equals reach as a percentage of the total population multiplied by frequency. 80% reach at 3× frequency = 240 GRPs.
TRP (Target Rating Points) is the same formula applied to the target audience instead of the total population. In planning, you'll hear "we need 500 TRPs over the flight" — that's the weight of the buy against the target demo.
When to use it: Use GRPs/TRPs when planning or evaluating linear TV, radio, or OOH buys. Digital teams increasingly use them for cross-channel planning alongside CPM-based digital metrics.
Open the GRP & TRP calculator →CPP — Cost Per Point
CPP is how much it costs to buy one rating point. If you spent $500,000 for 250 GRPs, your CPP is $2,000. It's the TV equivalent of CPM — a unit cost that lets you compare buys.
CPP varies by market, daypart, program, and demo. Prime-time CPPs are several times higher than daytime. Knowing your CPP helps negotiate rates and compare networks or dayparts on equal footing.
When to use it: Use CPP when buying or evaluating TV, radio, or any GRP-based media. It's the standard negotiation currency between agencies and broadcast sellers.
Open the CPP calculator →Gross vs. Net
In media billing, "net" is the actual media cost, and "gross" includes the agency commission on top. If the net media cost is $85,000 and the agency commission is 15%, the gross amount is $100,000.
The commission percentage is always expressed as a percent of gross, not net. This trips up many junior buyers. A 15% commission on $100,000 gross = $15,000. The net is $85,000, and $85,000 ÷ (1 − 0.15) = $100,000 gross.
When to use it: Use gross/net math whenever you're working with agency billing, insertion orders, or any document that shows both gross and net figures. Understand which number your system reports.
Open the Gross vs. Net calculator →Markup & Adjustment
Markup is a percentage added on top of a base cost. A 20% markup on $10,000 gives you $12,000. It's used for agency markups, vendor surcharges, and budget adjustments.
Don't confuse markup with margin. A 20% markup on cost is not a 20% margin on the selling price. Markup is relative to cost; margin is relative to revenue. $12,000 sell on $10,000 cost = 20% markup but only 16.7% margin.
When to use it: Use markup math when adjusting budgets up or down by a percentage, applying agency or vendor markups, or converting between cost and selling price.
Open the Markup & Adjustment calculator →Tech Fees & Fee Stacking
Programmatic media involves layers of technology fees — DSP fees, data fees, verification fees, ad-serving fees — each applied on top of the media net. Understanding how they stack is critical to knowing your true media cost.
Fees can be percentage-based (applied to the media net or to a running total) or fixed (a flat CPM or dollar amount). The order matters: stacking 10% + 10% is not the same as a single 20% fee. Always clarify the basis for each fee.
When to use it: Use tech fee math when building programmatic budgets, auditing platform costs, or explaining to a client why the working media dollars are less than the total budget.
Open the Tech Fees & Fee Stacking calculator →Percent Change
Percent change tells you how much a metric rose or fell compared to a baseline. It's the most common calculation in campaign reporting — "CPC decreased by 12% week over week."
Watch out for small denominators: if impressions went from 10 to 50, that's a 400% increase, but it's not necessarily meaningful. Always pair percent change with absolute values so stakeholders have the full picture.
When to use it: Use percent change in weekly reports, QBRs, and any time you need to contextualize how a metric moved between two periods.
Open the Percent Change calculator →Budget Pacing
Pacing tells you whether a campaign is spending on track relative to its flight dates. Even pacing divides the total budget equally across all days. If you've spent 60% of the budget but only 40% of the flight has passed, you're ahead of pace.
Most campaigns don't pace perfectly evenly — weekends may spend differently than weekdays, and heavy-up periods are intentional. The goal isn't perfect even pacing; it's knowing where you stand so you can adjust before it's too late.
When to use it: Use pacing math daily or weekly during a campaign flight to catch overspend or underspend early. It's especially important for fixed-budget campaigns with hard end dates.
Open the Budget Pacing calculator →Profit Margin
Profit margin is the percentage of revenue that's actual profit after costs. A 25% margin on $100,000 in revenue means $25,000 in profit and $75,000 in costs.
Margin is the inverse perspective of markup. They answer different questions: margin asks "what share of the selling price is profit?" while markup asks "how much did we add on top of cost?" Both are useful; know which one your team uses.
When to use it: Use profit margin when evaluating campaign profitability from the revenue side, setting pricing, or reporting financial performance to clients or leadership.
Open the Profit Margin calculator →What's next?
Now that you know the formulas, put them to work. Try any calculator above, check out the common planner questions, or grab the interview prep cheat sheet.