Paper LBO vs Full LBO

What Is A Paper LBO? 

A paper LBO is a skeletal version of the leveraged buyout model, done entirely by hand. No Excel, no calculator, sometimes not even pen and paper. Instead, just mental math, said out loud, and on the fly.

You’ll get a handful of inputs, usually some mix of:

• Purchase price, or an entry multiple of EBITDA
• A starting EBITDA figure
• How the deal’s funded — debt as a multiple of EBITDA, or the debt/equity split of the purchase price
• A growth rate
• A hold period

The entire paper LBO exercise should take you five to ten minutes, calculations and verbal walkthrough combined — a bit less in a fast final round, longer if they want you to poke at sensitivities. No complex debt schedule. No sensitivity table. Just numbers you articulate in front of an audience, judging whether you actually understand the idea.

A full LBO model is testing something altogether different. Are you capable of building a clean, precise model in hours, sometimes days? A paper LBO doesn't ask about that at all. It tests whether you have the right process in your head, without relying on software to execute it.

The exercise is a filter. Someone who only memorized the formulas freezes the second the calculator leaves their hand. Someone who actually understands the deal can build it from scratch, out loud, and walk you through how every number connects to the last. That’s exactly who a PE firm wants across the table.

What Is A Leveraged Buyout (LBO)?

A leveraged buyout is a private equity firm's acquisition of a company using mostly borrowed money. The firm doing the buying is called the sponsor. It writes an equity check for part of the purchase price and funds the rest with debt.

That debt is put on the target company, not on the sponsor. The company's own assets and cash flow secure it. If the deal goes badly, the sponsor loses its equity, and the lenders chase the company.

Not every company can support that kind of structure. Lenders want consistent cash flow and tangible assets to secure against, which is why LBOs cluster in mature, stable sectors and steer clear of early-stage or highly cyclical ones.

Why borrow, rather than pay all cash? Because a smaller equity check will yield a larger return.

Say a sponsor is buying a company for $1 billion. Pay all cash and double the business, and the sponsor makes $1 billion on a $1 billion check — a 100% return. Finance $600 million of that with debt instead, and the sponsor only writes a $400 million check. Double the business the same way, and that same $1 billion of value creation lands on a $400 million base instead — a large return, off identical underlying performance.

Over the holding period, the company pays down its own debt using its free cash flow. Every dollar of debt retired shifts value from the lender’s side of the balance sheet to the sponsor’s equity — it doesn’t show up as cash until exit, but it’s building the return that gets realized when the business is sold.

The typical hold period runs three to seven years, during which the sponsor works to grow revenue and earnings before selling. Returns get measured two ways: Multiple of Invested Capital (MOIC), which is exit equity divided by the original equity check, and Internal Rate of Return (IRR), which annualizes that MOIC over the holding period.

These are the moving pieces that combine to build an LBO model. Purchase price, the financing mix of debt and equity, the cash generation capacity of the business, the repayment of debt, the exit price for the transaction, and the eventual return on investment.

Projecting these pieces out in a full Excel build is what’s known as the full LBO model. Doing the same thing compressed into a five-to-ten-minute mental sprint is the paper LBO — the subject of this guide.

Paper LBO Vs. Full LBO: The Real Differences

Two exercises, same deal. Everything else about them is different.

A full LBO model is built in Excel. It has a debt schedule with multiple tranches, a full set of projected financial statements, sensitivity tables, and precise outputs carried to two decimal places. Building a proper model takes hours, sometimes days, and it's meant to be defensible enough to support a real investment decision.

A paper LBO is a handful of inputs and five to ten minutes of logical thinking — no spreadsheet, no formatting to lean on. The output is an approximation of IRR and MOIC, not a number precise enough to act on.

The last row is what firms actually care about. A junior who builds a flawless model but can't eyeball whether the IRR looks realistic is a liability. The WSO full LBO walkthrough covers what the detailed build looks like, if you haven't made one yourself.

How To Solve A Paper LBO Step By Step

The structure is just like a full LBO. What changes, however, is how loosely you handle the numbers at every step.

1. Round up your inputs: The interviewer says there’s $97 million in EBITDA and a 9.5x multiple; round to $100 million and 10x and move on. This isn’t laziness, rounding to clean numbers you can actually multiply in your head is part of the exercise. Precision is what you save for the full model in Excel.

2. Calculate the purchase price: EBITDA times the entry multiple. $100 million at 10x is a $1 billion enterprise value. Say it, don’t write it if you don’t have to.

3. Split the financing: Apply whatever debt-to-equity split you're given, or default to something standard like 60/40 if none is stated. I.e., $1 billion at 60/40 is $600 million of debt and $400 million of equity.

4. Estimate debt paydown: This is where many candidates overcomplicate it. You don’t need exact cash flow projections, just take a reasonable share of EBITDA as free cash flow available for debt paydown, say 40%, multiply by the hold period, and round. At $100 million of EBITDA and roughly $40 million a year going to debt paydown, that’s about $200 million repaid over a five-year hold. Leaving $600 million minus $200 million, or $400 million, of debt still outstanding at exit.

5. Work out the exit value: Grow EBITDA over the hold, say it climbs to about $120 million by year five. Exit at the same 10x you paid (assume entry equals exit multiple unless you’re told otherwise): $120 million times 10 is a $1.2 billion exit enterprise value.

6. Work out the return: Exit equity is what’s left after the debt, $1.2 billion exit value minus $400 million of remaining debt is $800 million. You put in $400 million and you’re pulling out $800 million, so you’ve doubled your money: a 2.0x MOIC, with $400 million of profit on top of your original stake.

That's a 2x multiple on money. From there, the steps to LBO modeling connect with the full model. The difference is you're estimating IRR with a shortcut instead of a formula. That's exactly where the Rule of 72 comes in.

The Rule Of 72 (114 and 144) 

Estimating an IRR mentally sounds impossible until you use this trick.

The Rule of 72 is a mental-math shortcut for figuring out how long it takes an investment to double at a given rate, or the contrary: what rate doubles it in a given time?

Divide 72 by the number of years, and you get the approximate annual return needed to double your money.

Hold for 5 years and want to double your equity? 72 divided by 5 is roughly 14%. That's your implied IRR, found in about two seconds, no calculator required.

Two variations are derived from the same trick. The Rule of 114 estimates tripling instead of doubling; divide 114 by the years instead of 72—the Rule of 144 estimates quadrupling, same method, different numerator.

So if a paper LBO produces roughly a 2x MOIC over five years, use 72. Roughly 3x, use 114. Roughly 4x, use 144. Match the multiple you calculated to the closest rule, divide by the hold period, and you have an IRR estimate that's usually the real answer.

This is exactly the trick candidates use on the WSO forum when working through paper LBO problems. Pick clean round numbers even when none are given, solve the deal structure first, then apply the rule that matches your multiple to reach a proper IRR.

The rule assumes compounding returns, so it gets less accurate at very short hold periods or very high rates. For the ranges that show up in a typical LBO, typically 3 to 7 years, IRRs are in the teens to twenties.

A Worked Paper LBO Example

Here's the technique from the forum, complete from start to finish.

The interviewer gives you a company doing "just under $100 million" of EBITDA at "around 10 times." First, you round immediately: $100 million, 10x. That's a $1 billion purchase price.

Now let’s say the financing is 60% debt, 40% equity, since nothing was specified. That's $600 million of debt and $400 million of sponsor equity.

Now the interviewer asks for the approximate return over a 5-year hold.  Work backward: check it against the Rule of 72. 72 divided by 5 is about 14%, which lines up with roughly a 2x. Round to a clean 2x and use that as the target.

Adding in the target exit equity to the remaining debt to find the required exit value. $800 million plus $400 million is $1.2 billion.

Now solve for what EBITDA growth that implies. At the same 10x exit multiple, $1.2 billion of exit value means $120 million of exit EBITDA. We started at $100 million; that's 20% growth over five years, roughly 4% a year, which is reasonable for a stable business.

Conclude with that number, and you've done the whole exercise. No spreadsheet, no calculator, and the logic comes from the target return instead of a guess, which is exactly the move that separates a strong candidate from an unreliable one.

Common Mistakes In A Paper LBO

Most candidates don't fail a paper LBO because they don't know the mechanics. They’ve drilled it countless times. They fail because of a handful of avoidable habits.

1. Refusing to round: Rounding isn't cheating, even if it feels like it. Trying to work with exact numbers here usually backfires. Hanging on to accuracy is what makes candidates freeze mid-calculation rather than show they understand the deal.
2. Being silent: 30 seconds of silence, staring at the ceiling, then announcing a number shows nothing good to the interviewer. This is a storytelling exercise; a simple "I am rounding to 100M in my head" does more for you in this interview than nothing at all. 
3. Not subtracting back for repayment: The equity you walk away with is the exit enterprise value minus the debt still outstanding, not the full exit value. Forget to subtract that remaining debt and your return comes out wildly too high. In the example above, that’s $1.2 billion exit value minus $400 million of debt, or $800 million of equity. Not $1.2 billion.
4. Not double-checking your answer: If the math produces a 400% IRR or a negative equity value, something is wrong. The best candidates catch these errors out loud, in real time. Weaker ones report the absurd number with a straight face. It’s ok to stop and go back; what matters most is getting it realistic and correct.
5. Overcomplicating the growth assumption: A flat annual growth rate is fine. Candidates who try to model year-by-year margin expansion or working-capital swings in their heads usually run out of brainpower and lose the plot before even finishing the exercise.
6. Not stating the assumptions clearly: Didn't get a debt-to-equity split or exit multiple? Say what you're assuming out loud before running with it. Two seconds of "I'll assume 60/40" saves you if the interviewer pushes back.

How To Practice A Paper LBO

This isn't a skill you can just cram the night before. It's built through repetition, the same way mental math only gets faster with practice and nothing else.

Drill the mental math. Multiply, multiply, multiply; divide a percent of a percent; multiple estimate rounds. If your mental math is sluggish, the rest on top of it will be too.

Know the Rule of 72 cold: 72 to double it, 114 to triple it, 144 to quadruple it. Don't work through it during the test. Just know the number.

Practice full paper LBOs against a timer. Randomize the inputs — EBITDA, multiple, debt split, hold — and run the whole thing start to finish, out loud, in under ten minutes.A couple of weeks of this and the test stops being scary.

Your execution has just as much to do with it as your final numbers. Doing the whole calculation and just spitting out a number at the end of five minutes loses the value, since this is a verbal test. Explain each and every step out loud like someone is actually watching, cause someone is.

Having a study partner beats solo drills. Getting someone to give you inputs you don’t expect gets you closer to real interview pressure than running the same practice sets alone ever will.

Build the foundation with WSO's LBO modeling course. Understanding the full model is what makes the paper version compress so easily.

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