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.

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.