Minimum 2 months of outflow. For longer or higher-risk projects: 3-4 months.

Can I float on credit cards?

Cards charge 18-25% — fast way to lose your renovation profit. Use only for true emergencies, pay off immediately at next draw.

What about my mortgage during build?

You're likely paying current mortgage AND construction loan interest AND alternate housing. Bake all three into outflow.

When does this matter most?

Owner-builders, ground-up construction, large remodels, or any project with >9 month timeline.

Project Cash Flow Calculator

Monthly cash flow = inflows (loan draws, owner contributions) − outflows (labor, materials) over project duration.

Result

Ending cash position

$8,000

Buffer sustains the gap.

Duration6 mo
Inflow$10,000/mo
Outflow$12,000/mo
Net per month$-2,000
Starting cash$20,000
Total inflow$60,000
Total outflow$72,000
Ending balance$8,000
Min buffer$8,000

Step-by-step

Net monthly = 10000 − 12000 = $-2,000.
Ending = start + net × months = 20000 + -2,000 × 6 = $8,000.
Cash position remains positive.

How to use this calculator

Estimate monthly project spend (labor, materials, fees).
Estimate monthly inflows (loan draws, owner deposits).
Set realistic project duration (add 25% to contractor estimate).
Enter your liquid cash on hand at start.

About this calculator

Most construction overruns are timing problems, not budget problems. A 6-month build that runs 9 months means 50% more carrying costs (interest, insurance, alternate housing) on the same scope. This calculator catches the moment when monthly outflows outpace inflows — even profitable projects can fail mid-build if the cash buffer runs dry. Carry at least 2 months of outflows as contingency cash beyond your loan draw.