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Contingency buffer for project fees in Excel
A fixed project fee without a contingency buffer is a best-case quote dressed up as a locked price. Build the fee from your hourly floor × estimated hours, then multiply by (1 + contingency %) so revisions and fuzzy scope do not erase your take-home — then put that number on the invoice.
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Free client rate calculator (Yellowcell)
One sheet: yellow inputs for take-home, tax cushion, billable time, project hours, and contingency %; gray formulas for hourly floor, day rate, and project fee. No macros. Soft path into the invoice kit when you are ready to bill.
Free client rate calculator Gumroad free download All free Yellowcell downloads
What a contingency buffer is (and is not)
Contingency is slack you price in before the client signs — not a surprise change order after you already underquoted. It covers expected unknowns: one extra revision round, a late asset, light scope drift. It does not replace a written change-order process for major new deliverables.
The formula
Project fee = hourly floor × estimated hours × (1 + contingency %).
Example: $90/hr × 40 hours × 1.20 (20% buffer) = $4,320 locked fee. Without the buffer you would quote $3,600 and eat every hour past 40.
Yellow inputs that matter
| Input (yellow) | Typical use |
|---|---|
| Hourly floor | From take-home, tax cushion, and billable weeks/hours — same floor as day and hourly quotes |
| Estimated project hours | Optimistic delivery plus unpaid admin / revisions you already expect |
| Contingency % | Often 10–15% when the brief is locked; 15–25% for fuzzy creative scopes; higher for first-time clients |
| Optional fixed add-ons | Licensing, stock, travel, or rush — keep as separate line items when possible |
Gray cells compute the fee. Keep formulas visible so you can defend the number if a client asks “why $X?”
How much buffer to use
- Tight brief + known client: 10–15%
- Creative / open-ended revisions: 15–25%
- New niche or stakeholder-heavy work: 25%+ or stay hourly until scope stabilizes
- Milestone billing: Put contingency on the whole fee, or weight later milestones if early discovery is the risky phase
Common traps
- Quoting best-case hours with 0% buffer, then eating every revision
- Hiding contingency inside a round number with no note of what it covers
- Using “what the market might pay” with no link back to your floor rate
- Calling the PDF an “estimate” after the calculator already produced a locked fee
- Spending the buffer on new scope instead of triggering a change order
From calculator to invoice
The calculator is for you. The client sees an invoice: deliverable name, quantity 1 (or milestone lines), fixed fee, tax if any, amount due, due date. Copy the contingency-inclusive project fee into your invoice workbook so the quote and the bill match.
Related SoloDesk guides
- Project fee calculator in Excel
- Client rate calculator in Excel
- Freelance day rate calculator in Excel
- Hourly rate calculator Excel vs pricing apps
- Name-your-price invoicing in Excel
Free rate calculator + invoice kit
Start with Yellowcell’s free hourly / day / project rate calculator (Netlify page, Gumroad, or Payhip). Set contingency % on the same sheet. When the project fee is locked, Sole Ledger puts a matching amount due on the invoice — expense log and 2026 mileage included, yellow inputs, no macros.
Free client rate calculator Gumroad free download Payhip (free) Buy invoice kit