Build a quote that includes a time buffer, an optional money contingency, and expenses. You will see the quote, the hours inside it, and the effective rate if you use none, half or all of the buffer. If you enter a floor rate, you will also see how much of the buffer you can use before dropping below that floor. It runs locally in your browser.
Start with the hours you honestly think the scoped work will take, then add a time buffer as a percentage of those hours. Labor is hours × (1 + time buffer %) × rate. Add any expenses you will pass through. A money contingency, if you use one, is then applied to that subtotal: (labor + expenses) × (1 + contingency %). The result is the quote. The buffered hours are the estimate plus the time buffer; they are the hours the quote can absorb before you are working past the plan.
The three effective rates in the result divide the same quote by three different hour counts: the raw estimate (none of the buffer used), the estimate plus half the buffer, and the estimate plus the full buffer. A higher rate when you finish early is not a bonus the calculator is promising. It is just the fee spread over fewer hours. If you enter a floor rate, the hours you can work before hitting that floor are the quote divided by the floor. The cushion is those hours minus the raw estimate.
A buffer is only as useful as the estimate underneath it. If the scope is likely to grow, price added work with a change order rather than hoping the buffer covers it. You can size that request with the change order cost calculator, or measure unpaid extras after they start with the scope creep cost calculator. To turn a day rate into a buffered project fee, use the day rate to project quote calculator.
With the default numbers, 32 hours at $85 with a 20% time buffer is 38.4 hours and $3,264 of labor. Adding $150 of expenses and a 10% money contingency produces a $3,755.40 quote. If the job stays at 32 hours, that fee is $117.36 an hour. If half the buffer is used, $106.69 an hour. If all 6.4 buffer hours are used, $97.80 an hour. Against a $65 floor there are 25.78 hours of cushion beyond the 32-hour estimate.
Flat-Fee Pricing Lab is a $7/month membership that adds one practical pricing tool for flat-fee freelancers each month. Month 01 is a change-order calculator plus 7 email scripts. Cancel anytime.
See Flat-Fee Pricing Lab ($7/mo) Get the free spreadsheet version
A time buffer is extra hours added to your estimate before you multiply by your rate, so a modest overrun does not immediately eat the fee. A money contingency is a percentage added after labor and expenses. This calculator lets you enter either or both. It does not tell you which percentage is right for a given job.
No. A buffer is a line you chose, and this page shows it as hours and money so you can see what happens if none, half or all of it is used. Whether you describe that line to the client is a communication choice, not something the arithmetic decides.
No. The estimate, the buffer percentage and the expenses are numbers you type. The page only multiplies and divides them. If the work takes more than the buffered hours, the effective rate keeps falling, just as it would on any other flat fee.