What contingency buffer should I use?

15% is a reasonable starting point for well-scoped work; increase it for projects with vague requirements or a client history of scope creep.

Why does a flat fee imply an hourly rate?

Dividing the flat fee by your estimated hours shows what you'd effectively earn per hour if the project takes exactly that long — useful for comparing against your target rate.

What happens if the flat-fee project takes longer than estimated?

Your effective hourly rate drops below the implied rate shown here, since the flat fee doesn't change but your hours worked do.

Does this account for client revisions or scope changes?

Only indirectly, through the contingency buffer — for significant scope changes, it's generally better to re-quote or bill separately rather than relying on the buffer alone.

Is a bigger buffer always safer?

It reduces your risk, but a buffer that's too large can make your quote uncompetitive — balance protection against winning the project.

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Finance

Freelance Project Quote Calculator

Build a quote from hours × rate plus a buffer, compared against a flat project fee.

🔒 Runs entirely in your browser — nothing here is ever uploaded

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Last reviewed 2026-08-30

About the Freelance Project Quote Calculator

Builds a project quote from estimated hours × your hourly rate plus a contingency buffer, and compares it against an alternative flat project fee — surfacing which side (you or the client) bears the risk of the project running over estimate.

100% Free Runs in Your Browser No Sign-Up Required

How to use it

Enter your estimated hours and hourly rate.
Enter a contingency/buffer percentage for scope creep or underestimation risk.
Optionally enter an alternative flat project fee to compare.
Read your hourly-based quote and how it compares to the flat fee.

Formula

Base quote = estimated hours × hourly rate. Buffer = base quote × contingency %. Quote (with buffer) = base quote + buffer. Implied hourly rate from a flat fee = flat fee ÷ estimated hours.

Worked example

40 estimated hours at $75/hr with a 15% buffer: a $3,450 quote. A $4,000 flat fee alternative implies $100/hr and is $550 higher than the hourly-based quote.

Interpreting your result

A flat project fee shifts scope-creep risk onto the freelancer — if the project runs over the estimated hours, the effective hourly rate drops. An hourly-plus-buffer quote shifts that risk toward the client instead. The contingency buffer here is a flat percentage, not a project-specific risk assessment — increase it for less-certain scopes.

Recommendations

• Increase your contingency buffer for projects with vague or likely-to-change scope — 15% is a reasonable starting point for well-defined work, more for uncertain scopes.
• A flat fee that's higher than your hourly-based quote isn't automatically the better deal — it's only better if you can actually finish at or under your estimated hours.
• Compare the flat fee's implied hourly rate against your actual target rate (see the Freelancer Hourly Rate Calculator) to judge if it's worth the risk.

Frequently asked questions

Hourly-plus-buffer shifts overrun risk to the client; flat fee shifts it to you. Neither is universally better — it depends on how confident you are in the scope and estimate.