Why It Matters
Loss-to-lease tells you how much rental income a property is forgoing because existing leases are priced below the current market rate. It is expressed in dollars and calculated as:
Loss-to-Lease = (Market Rent − Current Rent) × Number of Units × 12
If market rent is $1,200 but a tenant pays $1,000 under an older lease, that unit has $200/month, or $2,400/year, in loss-to-lease. Across a 20-unit-count building, the same gap equals $48,000 in annual unrealized income.
At a Glance
- Measures the gap between market rent and in-place (current) rent
- Expressed as an annual dollar figure
- Most relevant in multifamily and commercial properties with multiple leases
- A high loss-to-lease signals value-add upside — but also near-term risk if leases have long remaining terms
- The opposite concept, gain-to-lease, occurs when current rents exceed today's market (favorable for the owner)
- Lenders and underwriters review loss-to-lease when sizing loans and projecting stabilized cash flow
Loss-to-Lease = (Market Rent − Current Rent) × Number of Units × 12
How It Works
Loss-to-lease arises any time market rents rise faster than a landlord can renew or re-lease units. A tenant who signed a two-year lease at $950 is still paying $950 even if comparable units now rent for $1,100. The difference — $150/month — is the loss-to-lease for that unit.
The calculation has three inputs:
1. Market rent — the rent a vacant unit would command today, typically derived from comparable listings or a third-party rent survey. 2. Current (in-place) rent — what each existing tenant actually pays under their lease. 3. Unit count — the number of units affected; multiply by 12 to annualize.
Across a building, each unit may have a different loss-to-lease depending on when it was last leased. A common approach is to calculate the weighted average gap across all occupied units, then multiply by total units and 12.
Where it appears in underwriting:
When analyzing a residential-vs-commercial income property, investors start with Gross Potential Rent (GPR) — total income if every unit were leased at market rate. Loss-to-lease is subtracted from GPR to arrive at Gross Scheduled Income, which is then reduced by vacancy and credit loss to reach Effective Gross Income (EGI). This line matters most when reviewing a trailing-12-months rent roll — a seller may show strong historical collections while hiding a gap that will compress future income.
Agency-debt lenders underwrite to market rents on a stabilized basis, so a large loss-to-lease can reduce loan proceeds at acquisition. A proforma models the same upside — projecting cash flows as below-market leases expire and renew at market rates.
Real-World Example
Hiro is evaluating a 12-unit apartment building. The current rent roll shows an average in-place rent of $1,050 per unit per month. His market survey confirms comparable units in the submarket rent for $1,250.
Loss-to-Lease = ($1,250 − $1,050) × 12 units × 12 months = $28,800 per year
Eight of the twelve leases expire within nine months. Hiro models a phased increase to $1,200 per unit (slightly below market to limit turnover) and projects loss-to-lease falling under $7,200 in year two. The remaining four leases have 18 months left — so he prices the acquisition on current in-place income, treating the gap as prospective upside rather than guaranteed cash flow.
Pros & Cons
- Identifies hidden income upside that a static cash flow analysis would miss
- Gives buyers a concrete dollar figure to use in purchase price negotiations
- Helps lenders project stabilized NOI once leases roll to market
- Forces a rent roll review that surfaces lease expiration schedules and renewal risk
- In rising markets, a large loss-to-lease can signal a well-maintained, low-turnover asset
- Upside is not guaranteed — achieving market rent requires successful re-leasing and depends on demand and market timing
- Capturing the gap can trigger turnover, vacancy, and make-ready costs that offset some income gains
- Market rents can fall between acquisition and lease expiration, narrowing or eliminating the projected upside
- In rent-controlled markets, loss-to-lease may be legally unrecoverable even after lease expiration
- Sellers sometimes inflate market rent comparables to make the gap look larger than it is
Watch Out
Verify market rents independently. Do not accept the seller's rent survey at face value — pull comparables from listing platforms or hire a local property manager. A $200 gap that looks attractive can shrink to $80 after honest market analysis.
Check lease expiration dates before pricing. If all below-market leases expire in 12 months, the upside is near-term. If half expire in 36 months, your projections must reflect that delay.
Watch for rent-controlled units. In jurisdictions with strict rent stabilization, even expired leases may cap allowable increases to 3–5% annually, making the full loss-to-lease essentially unrecoverable near-term.
Distinguish loss-to-lease from economic vacancy. A vacant unit has no lease and no loss-to-lease — it has no income at all. Conflating the two leads to double-counting upside in your proforma.
The Takeaway
Loss-to-lease is one of the clearest signals of value-add potential in an income property. A large gap between market rent and in-place rent means embedded upside — income that materializes as leases roll over. But that upside is only as real as the lease expiration schedule, the local market, and your operating plan. Verify market rents independently, model lease timing carefully, and price the deal on current in-place income.