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Tenant Improvement Overage Calculator

TI allowances rarely cover premium buildouts. This calculator sizes the tenant gap.

Sqft

Actual TI $/sf

$/sf

TI allowance $/sf

$/sf

Amortization rate

Amortization years

Total overage

$300,000

Monthly amortization

$3,640

Rent bump $/sf

2.91

How the math works

Overage = (actual TI − allowance) × sqft. Amortize at market rate into monthly rent bump.

Tenants are often surprised by overage amortization math. A $20/sf overage on 15k sf at 8% over 10 years shows up as $4/sf additional rent — a 10-15% effective rent increase over the face rate. Factor this in when comparing LOIs side-by-side.

Editorial noteMaintained by EveryCalc - Reviewed June 2026

EveryCalc calculators are designed for fast, practical estimates with transparent inputs and no required account. We use plain formulas, visible assumptions, and related tools so visitors can check the result from more than one angle.

Results are informational only. For financial, tax, legal, medical, construction, or other high-impact decisions, verify the output against primary sources or a qualified professional.

Learn more about our review process on the EveryCalc methodology page.

How this calculator works

What this page estimates

This Tenant Improvement Overage Calculator is built to give a quick, browser-based estimate for tenant improvement overage. TI allowances rarely cover premium buildouts. This calculator sizes the tenant gap. The inputs stay on the page during normal use, and the result should be treated as an estimate for planning, comparison, or education rather than professional advice.

Calculation approach

The calculator applies the standard relationship implied by the inputs, then formats the answer so it can be checked and reused. For finance tools, the most important step is using consistent units, rates, time periods, and assumptions before comparing the result with another calculator or outside quote.

Example workflow

For example, start with a realistic value you already know, change one input at a time, and watch how the answer moves. That makes it easier to tell whether the result is being driven by the main amount, the rate, the time period, or a unit conversion.

Practical checks

Use current, real-world numbers when the result affects money, health, tax, or legal decisions.
Run a low, base, and high case when the inputs are estimates.
Check the related calculators below when the next decision depends on a different assumption.

How to interpret the tenant improvement overage result

Best use

Use the result as a planning number for comparing payments, rates, returns, tax reserves, or cash-flow choices before you request a quote or make a commitment.

Cross-check

Compare the answer with the contract, lender estimate, tax form, brokerage statement, payroll record, or invoice that will control the real-world outcome.

Watch for

Do not rely on a single optimistic rate, return, or fee assumption. Money pages work best when you run low, base, and high cases and keep professional advice separate from the estimate.

This page belongs to the Finance calculator library, so the answer should be read in the context of the decision you are modeling rather than as a universal rule.

Before relying on this tenant improvement overage estimate

Most calculator mistakes come from the inputs, not the arithmetic. Use this short audit before you reuse the answer in a spreadsheet, quote, application, or important conversation.

Confirm source numbers

Match balances, rates, fees, taxes, income, and payment dates against the lender quote, payroll record, tax form, statement, invoice, or contract.

Separate cash flow from total cost

A lower monthly payment can still cost more over time if fees, interest, taxes, or a longer term are hidden in the structure.

Run conservative cases

Test at least one higher-cost or lower-return case before using the output for a purchase, refinance, investment, loan, or tax decision.

Rerun this page when the rate, price, term, fee, tax rule, income, expense, or expected holding period changes.

How to Use

Enter sqft.
Enter actual TI cost $/sf.
Enter TI allowance $/sf.
Enter amortization option rate %.
Enter amortization years.
Read overage and rent bump.

Frequently Asked Questions

Typical overages?

Office: $10-40/sf overage on $60-80/sf allowance common. Retail: $15-30/sf. Medical/lab: often $100-200/sf overage. Professional services: $5-15/sf overage. Premium finishes, AV, and specialty spaces drive the gap.

Amortization option?

Landlord funds overage; tenant repays via rent bump over lease term. Rate typically prime + 2-4% or flat 8-10%. Monthly add-on of $0.50-2.50/sf depending on overage size and term.

Self-fund vs amortize?

Self-fund: no interest, but large cash requirement. Amortize: preserves cash, builds interest cost. For $20/sf overage on 15k sf = $300k, amortizing at 8% over 10 years adds ~$2.5k/month rent — often worth it vs upfront cash.