Free Cash Flow & S-Curve Calculator

The S-curve is your cumulative billing plotted over the life of the job. Because most projects mobilize slowly, peak through the bulk of the work, and taper at close-out, the running total of dollars billed traces an "S". Owners, GCs, and lenders read that curve to see how much cash the project needs and when.

Spread the contract value across the months of the job as a billing percentage per period, then multiply each percentage by the contract value to get the dollars you will bill that month. This tool seeds those percentages from a distribution shape, lets you override any row, and instantly rolls them up into the cumulative draw and cash-flow S-curve.

Bell and S-curve suit most schedules — steady ramp-up, a peak mid-job, and a taper. Front-loaded fits jobs with heavy early mobilization, material buys, or stored-material billing; back-loaded fits work that lands at the end. Linear (even monthly billing) is a quick planning baseline. Start from a shape, then hand-edit the periods you have better numbers for.

Retainage is the percentage an owner withholds from each payment until the job is substantially complete — commonly 5–10%. It means your net cash in every month is less than what you billed, and the held amount is only released at the end. This calculator shows the retainage withheld and the net payment per period plus the total held across the job.

Yes — the free construction cash-flow S-curve Excel template builds the same draw schedule and cumulative curve with live formulas. Use the links below this calculator, or let Field PM forecast the curve automatically from your billings.