Definition
Cost of capital buffer is the extra return you require above the base cost of capital to cover model risk and uncertainty.
Formula
Target return = cost of capital + buffer
Example
If WACC is 10% and buffer is 3%, target return is 13%.
How to use it
- Use larger buffers for volatile cash flows or new markets.
- Document buffer logic to keep decisions consistent.
Common mistakes
- Applying the same buffer to low-risk and high-risk projects.
- Double-counting risk if the discount rate already includes it.
Why this matters
This term matters because cash timing and risk are usually the difference between a plan that works on paper and a plan that survives. Use consistent definitions so decisions are comparable over time.
Practical checklist
- Write a 1-line definition for "Cost of Capital Buffer" that your team will use consistently.
- Keep the time window consistent (weekly/monthly/quarterly) when comparing trends.
- Segment results (channel/plan/cohort) before drawing big conclusions from blended averages.
- Sanity-check with a related calculator from the same category on MetricKit.
- Read the related guide (e.g., WACC explained: how to estimate a discount rate for DCF) for context and common pitfalls.
Where to use this on MetricKit
Calculators
- Pro Rata Investment Calculator: Estimate how much you need to invest in a new round to maintain your ownership percentage (simplified).
- Option Pool Shuffle Calculator: Estimate founder dilution impact when the option pool is increased to a target percent of post-money (simplified).
- SAFE Conversion Calculator: Estimate how a SAFE converts in a priced round using a valuation cap and/or discount (simplified).
- Convertible Note Conversion Calculator: Estimate how a convertible note converts in a priced round with interest plus a valuation cap and/or discount (simplified).
- Liquidation Preference Calculator (1x): Estimate investor proceeds at exit under a simple 1x non-participating liquidation preference vs converting to common (simplified).
Guides
- WACC explained: how to estimate a discount rate for DCF: A practical guide to WACC: what it is, how to compute it, and how to use it (carefully) as a DCF discount rate.
- Investment decision metrics: NPV vs IRR vs payback vs PI: A practical guide to investment decision metrics: when to use NPV, when IRR misleads, and how payback and profitability index fit in.