How to Underwrite a C-Store: Gallons, Inside Sales, and the Dark Value Floor

By Cole Borror · Director of Acquisitions, Sierra Capital Club · Reviewed September 2026

The short answer: A convenience store net lease has to be underwritten at four levels: store economics (gallons, fuel margin, inside sales, and category margin), lease coverage (four-wall EBITDAR against rent), guarantor capacity, and real estate recovery (what the site is worth as-dark, net of environmental and downtime costs). Fuel volume alone is incomplete because margin, inside sales, tank liability, and alternative-use value determine whether the rent and the residual are durable.

In this article

1. The sign and the cap rate are the last two things to underwrite
2. Start with exactly what you are buying
3. The four-layer underwriting table
4. Fuel volume: traffic with a thin and moving margin
5. Inside sales: where the gross profit is built
6. Convert store economics into rent capacity
7. A worked store stress test
8. Environmental risk is part of the capital stack
9. The dark value floor
10. Future demand and format risk
11. The minimum data room
12. FAQ

The Sign and the Cap Rate Are the Last Two Things to Underwrite

Gallons bring traffic. Inside sales create margin. Dark value tells you what is left when the operator does not.

Two branded fuel sites, same rent, same cap rate, same 15-year lease. One pumps 2.4 million gallons a year on a signalized corner with a kitchen that does $40,000 a week. The other pumps 900,000 gallons on a road the state is about to widen, with a supply contract that expires in three years and a tank system from 1994. The offering memoranda look nearly identical. The investments are not.

A c-store is not one income stream. It is fuel traffic, inside-margin production, operator credit, lease economics, specialized real estate, and environmental exposure, all stacked on top of each other. The lease converts store performance into rent until it stops doing that. Underwriting has to explain both how the rent gets paid and what recovery looks like when it does not.

Start With Exactly What You Are Buying

In a net lease acquisition you are buying fee-simple real estate subject to a lease. You are not buying the operating business, the inventory, the licenses, the equipment, or the fuel supply contract, and the difference matters more in this sector than any other.

Confirm who owns the underground storage tanks, dispensers, canopy, signage, car wash, kitchen equipment, and other improvements. Tanks in particular can be owned by the operator, the landlord, or a fuel distributor, and ownership drives environmental responsibility. Identify the tenant and guarantor, whether the lease is a unit lease or part of a master lease, the term, increases, options, assignment rights, environmental indemnity, casualty and condemnation treatment, and any closure or go-dark rights. Determine whether the fuel brand and supply rights run with the site, the tenant, or a separate jobber, because a site that loses its brand on a tenant default is a different piece of real estate.

Keep business value, equipment value, and real property value in separate columns. They interact, but they are not the same thing, and a seller's broker will blend them if you let them.

The Four-Layer Underwriting Table

Fuel Volume: Traffic With a Thin and Moving Margin

Ask for monthly gallons by grade for at least three years. Annual fuel revenue is nearly useless, because it moves with the price of crude and tells you nothing about volume or margin.

Separate three things: gallons, gross cents per gallon, and net margin after card fees, freight, discounts, taxes, shrink, and the terms of the supply agreement. A site can show rising fuel revenue and falling profit at the same time. Compare transaction counts, gallons per transaction, dayparts, diesel mix, and fleet accounts. Then walk the forecourt: pump count, stacking, canopy condition, tank capacity, and delivery access all cap volume regardless of demand.

Investigate what is changing around the site. New competitors, road projects, access changes, and median closures can move gallons 20% in a year. The state DOT's project list is part of the underwriting file.

Here is why gallons alone mislead. NACS reported that in 2025, fuel accounted for 65% of total convenience industry sales but only 38.8% of gross profit dollars. Revenue share overstates fuel's economic contribution by almost half. A store that "does $8 million a year" may be earning most of its gross profit inside.

Inside Sales: Where the Gross Profit Is Built

Review inside sales by category: cigarettes and other tobacco, packaged beverages, beer, lottery commissions, foodservice, prepared beverages, salty snacks, candy, and general merchandise. Equal sales dollars do not produce equal margin. Cigarettes are high volume and thin. Foodservice and fountain are the opposite. A store with $1.6 million of inside sales that is 40% tobacco is a different store than one that is 30% foodservice.

NACS reported $341.2 billion of in-store sales in 2025, with foodservice at 28.5% of inside sales but 38.9% of in-store gross profit. That is the national picture, and it is useful as a benchmark, never as a store-level assumption. Test the conversion rate from fuel customers to store customers, whether foodservice creates repeat destination traffic on its own, and whether the kitchen's labor cost is eating its margin.

Then reconcile. POS reports, sales tax returns, bank deposits, supplier statements, payroll records, and inventory movement should tell one consistent story. When they do not, the gap is the diligence finding.

Convert Store Economics Into Rent Capacity

Build four-wall EBITDAR (earnings before interest, taxes, depreciation, amortization, and rent) the same way for every store you look at, then divide by the lease's actual rent and obligations. That is rent coverage.

Normalize before you compute it: owner compensation, one-time expenses, supplier rebates, related-party charges, deferred maintenance, and a realistic capital reserve for dispensers, canopy, coolers, and eventually tanks. Then stress it: lower gallons, compressed fuel margin, softer inside transactions, higher wages, rising card fees, insurance and utilities.

Two asymmetries to remember. A high-performing site can still have weak lease support if the named tenant is a thin entity, which sends you to the guaranty analysis. And a strong guarantor does not make an over-rented unit healthy; it just means the guarantor subsidizes the store until it decides not to renew.

There is no universal coverage threshold. The cushion a store needs depends on its volatility, the lease term, guaranty depth, upcoming capital needs, and what the real estate is worth without it. A 1.5x store with a deep guarantor on a corner with three alternative users is a different risk than a 2.0x store with a single-unit operator on a rural highway.

A Worked Store Stress Test

Illustrative single site. Rent under the lease is $150,000 per year.

The base case looks comfortable. Three ordinary things happening at once, none of them dramatic, take the store below 1.0x. Three cents of fuel margin, 10% of gallons, and one extra employee are not tail risks in this business; they are a normal bad year. The question the stress test answers is not "is 1.92x good?" It is "how many ordinary bad things can happen before this store cannot pay me?"

Environmental Risk Is Part of the Capital Stack

Every c-store with fuel is a regulated underground storage tank site, and environmental exposure should be underwritten like a lien: quantified, allocated, and priced.

Obtain a Phase I environmental site assessment at minimum, with qualified environmental counsel and consultants, and pull the state regulatory file: tank registration, age, construction (single- or double-wall, fiberglass or steel), leak detection, testing history, release reports, closure status, financial responsibility mechanism, and eligibility for the state cleanup fund. A clean Phase I does not mean there is no contamination. A recognized environmental condition means further investigation, which means time and money before closing.

Then allocate it in the documents: who investigates, who remediates, who reports, who indemnifies whom and for how long, access rights, insurance, and what survives lease termination. The EPA is direct about the stakes: purchasers of petroleum-contaminated property may face cleanup liability, and petroleum sites do not always fit neatly inside the landowner protections that apply to other contaminants.

The most expensive diligence mistake I see in this sector is treating a tenant's environmental indemnity as the answer. An indemnity from a thin LLC is worth exactly what the LLC is worth. If the tenant fails, the tanks are yours, the regulator is calling you, and the indemnity is a line in a bankruptcy claim.

The Dark Value Floor

Dark value is the value of the real estate with the current lease and operator removed from the assumptions. It is the downside scenario, not a guaranteed floor, and it is the number that separates a c-store net lease from a bond.

Analyze the land: traffic counts, access and signalization, parcel size, zoning and entitlements, and whether the corner works for another fuel operator, a QSR with a drive-thru, an auto-service use, or something else entirely. Then subtract what it costs to get there: downtime, carrying costs, taxes, insurance, security, repairs, leasing costs, demolition if the building is obsolete, tank removal or closure, and the environmental uncertainty that any buyer of a former fuel site will price.

Two assumptions to refuse. Do not assume the current rent is market rent; on a sale-leaseback it frequently is not. And do not assume the next operator inherits the brand and supply agreement; those may terminate with the tenant, and an unbranded site sells fuel at a different margin.

Keep three values separate: going-concern value (the business plus the real estate), leased-fee value (what you are paying, based on the lease), and dark real estate value. Institutional diligence tracks these distinctly; SEC exhibits for fuel-site portfolios have listed "Appraised Value As Is" and "Appraised Dark Value" side by side for exactly this reason. If leased-fee value is $2.5 million and dark value net of remediation and downtime is $900,000, the $1.6 million spread is what you are paying for the lease and the guaranty. Name it.

Future Demand and Format Risk

Underwrite the site's next fifteen years, not its last three. Traffic patterns shift with road projects and development. Competition arrives in the form of a new travel center two exits away. Foodservice capability, or the lack of it, determines whether the store participates in the category that generates the most inside gross profit. Forecourt configuration limits diesel and fleet business.

Fuel demand over the lease term is uncertain, and claims in either direction should be sourced and scenario-based rather than predictive. The underwriting question is not "will EVs kill gas stations." It is whether this parcel supports another use if fuel volume declines faster than expected, and whether the tenant's renewal probability at year fifteen depends on a format that may not exist. Both answers feed back into dark value.

The Minimum Data Room

Before you price a c-store net lease, you should have: the lease, all amendments, the guaranty, and the rent schedule; three years of monthly gallons by grade, fuel margin, and fuel transactions; inside sales by category with gross margins, transaction counts, basket size, labor, and shrink; three years of store-level financial statements; fuel supply, branding, rebate, and equipment ownership agreements; guarantor financial statements, liquidity, leverage, and a schedule of other lease obligations; tank registration, testing, and permit records, environmental reports, insurance, and indemnities; traffic counts, access details, competition map, DOT project list, and zoning; survey and title; and an as-dark valuation net of downtime, capital, and remediation.

Separate what the seller told you from what a third party or a source document verified. The first column is a story. The second is underwriting.

Underwrite Payment and Recovery

The cap rate prices the lease. Gallons and inside margin explain whether the store can carry it. The guaranty tells you who else stands behind it. Dark value tells you what recovery looks like when those protections fail. A c-store becomes understandable only when all four answers point to the same price.

For why the cap rate is the beginning of that analysis and not the end, read cap rate is not a return. For the lease obligations that determine who owns the tanks and the roof, see what a NNN lease actually is. And for confirming that the lease you underwrote is the lease the tenant recognizes, see estoppels and SNDAs in plain English.

Frequently Asked Questions

What is a good rent coverage ratio for a c-store? There is no universal threshold. Required coverage depends on the store's volatility, lease term, guarantor depth, upcoming capital needs, and the real estate's as-dark value. Compute four-wall EBITDAR consistently, stress it, and ask how many ordinary bad events the store can absorb before it falls below 1.0x, as shown in the stress test above.

Are gallons or inside sales more important? Neither alone. Gallons drive traffic and fuel gross profit; inside sales, particularly foodservice, typically drive the majority of gross profit dollars. National data shows fuel at 65% of sales but under 40% of gross profit. Underwrite both, and underwrite the conversion between them.

Who pays for environmental cleanup in a NNN lease? Whatever the lease and environmental indemnity say, enforced against whatever entity signed them. Regulators can look to the property owner regardless of the lease. Confirm tank ownership, the scope and survival of the indemnity, and the tenant's capacity to honor it, and consider environmental insurance where the tenant's credit is thin.

What does dark value mean for a gas station? The value of the real estate with the current lease, operator, brand, and supply agreement removed, net of downtime, demolition, tank closure, and environmental costs. It is a downside scenario used to size how much of the purchase price depends on the lease continuing to perform.

Related reading in this series

• What a NNN lease actually is, and the different kinds of commercial leases
• Cap rate is not a return: what it actually tells you
• Corporate guaranty vs. franchisee guaranty: what you're actually buying
• Estoppels and SNDAs in plain English
• Nine ways a net lease deal actually gets done
• Sale-leasebacks from the operator's side of the table
• PropCo/OpCo separation: an operator's guide
• The 1031 exchange timeline that kills deals

About the author. Cole Borror is Director of Acquisitions at Sierra Capital Club, a Dallas-based net lease investment and development firm. He works on NNN and NN acquisitions, build-to-suit development, sale-leasebacks, and operator partnerships, including convenience and fuel sites. Connect at coleborror.com.

This article is for educational purposes only and is not legal, environmental, tax, or investment advice. All store figures are illustrative. National benchmarks are cited as of their publication dates and are not store-level assumptions. Environmental conditions and liabilities require qualified consultants and counsel.