Estimate income gaps between projects.
Project-based income arrives in lumps while expenses arrive every month, and the gap between contracts is where that mismatch bites. Converting monthly expenses to a weekly burn shows what one typical gap costs; multiplying the gap by projects per year shows how much of the year is unbooked. A buffer of one and a half gaps absorbs the normal case of a contract starting later than promised.
Gap cost
Weekly burn = monthly expenses x 12 / 52; cost per gap = weekly burn x gap weeks; unbooked weeks = gap weeks x projects per year
Because contract gaps rarely align to calendar months. A weekly burn rate matches the granularity at which projects actually start and finish.
Timing. Annual income can comfortably exceed annual expenses while a single long gap still empties the account, which is what the buffer figure addresses.
Overlap pipeline work with delivery: book the next engagement before the current one ends, or keep a retainer client that pays through quiet weeks.