Multiply your loan balance by the annual rate divided by 52, then by the weeks of delay: loan × (rate ÷ 52) × weeks. A $400,000 loan at 8% costs about $615 per week, so a four-week bidding delay costs roughly $2,460 in interest with nothing built.
Every week between loan closing and real progress has a price printed on it. Most builders never compute it, which is why six weeks of phone-tag bidding feels free. It is not.
The formula
Carrying cost = loan balance × (annual rate ÷ 52) × weeks of delay
At 8% annual, a $400,000 balance costs about $615 a week. Four weeks of bid-out: about $2,460. Interest accrues on drawn balances, so early-stage delays on partially drawn loans cost less than this worst case — but land draws, lot loans rolled in, and closed-but-idle loans mean many builds carry serious balances from day one.
Reference table (8% annual rate)
| Loan balance | Per week | 2 weeks | 4 weeks | 6 weeks | 8 weeks |
|---|---|---|---|---|---|
| $250,000 | $385 | $769 | $1,538 | $2,308 | $3,077 |
| $400,000 | $615 | $1,231 | $2,462 | $3,692 | $4,923 |
| $600,000 | $923 | $1,846 | $3,692 | $5,538 | $7,385 |
Run your own numbers with the interactive calculator on the builders page — it takes your loan size, rate, and delay and does this math live.
Where the weeks actually go
The classic silent delay is the bid-out: 15–20 scopes, 40–50 contractor conversations, callbacks that come or do not. Solo, that commonly takes 6–8 weeks — $3,700–$4,900 of interest on a $400,000 balance, plus 30–40 hours of your time, worth $2,250–$6,000 on its own. And a rushed bid-out that skips leveling trades one cost for a worse one: change orders.
Three ways to spend fewer weeks
- Bid before you close. Run the bid-out while the loan is still in underwriting and the meter is off. A leveled trade budget also strengthens the loan file itself.
- Compress the bid-out. A Build Pack delivers all scopes priced and leveled in about 10 business days flat — against the table above, the fee frequently pays for itself in avoided interest alone.
- Schedule from start windows. Gaps between trades mid-build carry the same weekly price. Scope sheets with stated earliest start windows are how you build a schedule without holes.