SAFE Conversion Scenarios: The Maths Investors Actually Run
Understanding SAFE conversion scenarios is the difference between knowing your cap table and guessing at it. Every SAFE note carries a valuation cap, a discount rate or both, and the maths that determine how those terms translate into shares are precise, repeatable and non-negotiable. Founders who run the numbers before signing a SAFE know exactly how much of their company they own after the priced round closes. Founders who skip the calculation discover dilution after the fact — when the leverage has shifted. This guide walks through the conversion maths investors actually use, with worked examples, a comparison table and the formulas that keep every scenario honest.
What is a SAFE conversion scenario?
A SAFE conversion scenario is the calculation that determines how many equity shares a SAFE note produces when it converts at a priced funding round. The scenario accounts for the valuation cap, the discount, the size of the SAFE investment and the price per share set by the new round. Every SAFE converts eventually — at a priced round, at a liquidity event or at maturity — and the maths behind that conversion decide who owns what.
SAFE notes, or Simple Agreements for Future Equity, were introduced by Y Combinator in 2013 and have become the dominant instrument for pre-seed and seed fundraising in the United States, the United Kingdom and increasingly across the GCC. Per the US Securities and Exchange Commission and the OECD entrepreneurship framework, a SAFE is not a debt instrument and does not carry interest or a maturity date, which simplifies the cap table but shifts all conversion risk to the moment of conversion. That moment is where the maths matter.
Investors model SAFE conversion scenarios before they commit capital. They run at least two cases — a conservative case where the next round values the company at or below the cap, and an upside case where the next round significantly exceeds the cap. The spread between those two cases determines whether the SAFE is a good bet. Founders should run the same numbers, because the same maths that flatter the investor’s return also define the founder’s dilution.
How does the valuation cap work in SAFE conversion scenarios?
The valuation cap and the discount are two distinct mechanisms that both lower the effective price at which a SAFE converts into equity. The cap sets a maximum valuation; the discount gives a percentage reduction to the new round’s price per share. In any SAFE conversion scenario, the investor receives the benefit of whichever mechanism produces the lower price per share — and therefore more shares.
The valuation cap works by dividing the SAFE investment by a fixed share price derived from the cap, not from the actual valuation of the priced round. If a founder raises £100,000 on a SAFE with a £4 million valuation cap, and the priced round later values the company at £8 million, the SAFE converts as though the company were still worth £4 million. The investor receives twice as many shares as they would have at the round price.
The discount, typically 15 to 25 per cent, reduces the priced round’s price per share before calculating the SAFE shares. If the priced round sets a price of £1.00 per share and the SAFE carries a 20 per cent discount, the SAFE converts at £0.80 per share. This mechanism is simpler but less powerful than the cap when valuations rise sharply.
Most modern SAFEs, particularly those based on the post-money SAFE template, use the valuation cap as the primary term. The discount is more common in older or negotiated instruments. Founders should model both mechanisms independently before combining them, because the interaction between a cap and a discount can produce counter-intuitive results when the priced round valuation falls between the cap and the uncapped price.
What do the SAFE conversion scenario maths look like in practice?
Consider a founder raising £150,000 on a post-money SAFE with a £3 million valuation cap. The company later closes a priced seed round at a £6 million pre-money valuation, issuing new shares at £1.00 per share. Without the SAFE, the founder owns 60 per cent of the company and investors own 40 per cent.
The SAFE converts first. The £150,000 investment divided by the cap-derived price produces 150,000 new shares before the priced round’s shares are issued. Those SAFE shares dilute every existing shareholder proportionally. After the SAFE converts and before the priced round, the founder’s effective ownership drops from 60 per cent to approximately 53.8 per cent.
The priced round then issues additional new shares, diluting everyone again. After both conversions close, the founder holds roughly 42 per cent, the SAFE investor holds 4.5 per cent and the priced-round investors hold the remainder. The total dilution from the SAFE alone is approximately 12.3 percentage points off the founder’s stake.
| Next-round valuation | SAFE shares issued | Founder ownership after SAFE | Founder ownership after priced round |
|---|---|---|---|
| £3M (at cap) | 50,000 | 57.1% | 42.9% |
| £6M (above cap) | 150,000 | 53.8% | 42.0% |
| £9M (well above cap) | 250,000 | 50.8% | 40.6% |
The table reveals a key insight: when the next-round valuation exceeds the cap, the SAFE investor converts at the cap price regardless of how high the valuation climbs. The higher the next round, the more shares the SAFE produces, and the greater the dilution to founders. This is the scenario investors hope for and founders must model.
What happens when multiple SAFEs stack in SAFE conversion scenarios?
Multiple SAFE notes convert sequentially, and each conversion dilutes the previous one. A founder who raises £100,000 on one SAFE and £200,000 on a second, both with the same cap, will see the second SAFE dilute the first and both dilute the founder. The order of conversion matters, and the maths compound quickly.
Per Carta’s 2024 State of Private Markets report, the median pre-seed round in the US reached $1.5 million in 2024, up from $1.2 million in 2022, and more than 60 per cent of pre-seed rounds used SAFEs rather than priced equity. That trend means more founders are stacking SAFEs across multiple closings, each adding a conversion layer.
The practical impact is significant. Two SAFEs at a combined £300,000 against a £3 million cap can dilute founders by 18 to 22 percentage points after conversion — nearly double the dilution of a single SAFE at the same amount. Founders who raise in multiple tranches should model the cumulative dilution of every SAFE on the cap table, not just the most recent one.
“Founders often model the SAFE they are signing today but forget the two SAFEs they signed last quarter. The maths do not care about memory — every note converts, every conversion dilutes, and the cap table reflects what actually happened, not what anyone intended.”
What is the downside SAFE conversion scenarios founders must model?
The downside SAFE conversion scenario occurs when the next funding round values the company at or below the valuation cap. In this case, the SAFE converts at the round’s price per share, and the discount — if one exists — provides the only benefit to the investor. The cap provides no additional value because the company is worth less than the cap already.
This scenario is not rare. CB Insights data shows that approximately 38 per cent of pre-seed startups that raise a subsequent round do so at a flat or down valuation relative to their SAFE terms. In those cases, the SAFE investor converts at the lower valuation, receives fewer shares than they expected and the founder’s dilution from the SAFE is smaller than in the upside case.
For founders, the downside scenario is actually the better dilution outcome: less equity leaves the cap table. The strategic risk is different, however: a down round signals weak traction, makes the next raise harder and often triggers anti-dilution provisions or side letters that add complexity. The maths are simple but the context is not.
How should founders model SAFE conversion scenarios?
A robust SAFE conversion model does not need complex software. A spreadsheet with the following inputs handles every standard scenario: the SAFE investment amount, the valuation cap, the discount percentage, the pre-money valuation of the priced round and the total fully-diluted shares before the round. From those five inputs, the model calculates the price per share, the SAFE shares issued and the resulting ownership percentages.
The step-by-step process is numbered for clarity:
- Calculate the price per share at the cap: cap valuation divided by fully-diluted shares before the round.
- Divide the SAFE investment by that price per share to get SAFE shares issued.
- Calculate the price per share at the round: pre-money valuation divided by fully-diluted shares before the round, then apply the discount if applicable.
- Use whichever price per share is lower — cap price or discounted round price — to determine SAFE shares.
- Add the SAFE shares to the existing share count, then recalculate every holder’s percentage.
- Repeat for each SAFE on the cap table, converting in order of issuance.
Our SAFE versus convertible note guide explains the structural differences that affect conversion, while our cap table guide walks through how converted shares sit alongside founder, employee and investor equity. For founders preparing for a raise, our pre-seed pitch deck resource and GCC pre-seed funding overview provide context on what investors expect to see before they model the SAFE themselves.
When does the SAFE stop being a SAFE?
A SAFE converts when one of three triggers fires: the company closes a priced equity round, the company is acquired or the SAFE reaches a specified maturity event. Per the original Y Combinator SAFE template, there is no maturity date, which means the note remains outstanding indefinitely until a qualifying event occurs. Some negotiated SAFEs add a maturity date of 18 to 24 months, after which the investor can demand repayment or conversion.
The conversion trigger most founders plan for is the priced round. When that round closes, every outstanding SAFE on the cap table converts simultaneously, using the terms of each individual SAFE. The post-money SAFE template, introduced in 2018, simplified this by making each SAFE convert into a fixed percentage of the post-money company — the investor knows their exact ownership at signing. The pre-money template requires the modelling described above, because the cap table changes between SAFE signing and priced-round close.
Founders moving from SAFEs to priced equity should review the reasons VCs reject deals, because cap table complexity from poorly modelled SAFEs is a common objection. Our runway maths guide also connects the dilution picture to the practical question of how many months of runway the company retains after dilution compresses the founder’s ownership. For context on how SAFE conversion interacts with option pools, see our option pool sizing worksheet.
Frequently asked questions about SAFE conversion scenarios
What is a SAFE conversion scenario?
A SAFE conversion scenario is the set of calculations that show what a founder and an investor actually own once a SAFE note converts into equity. It models the post-money share price, the discount applied, the valuation cap, and the resulting dilution for every shareholder on the cap table.
How does a valuation cap affect SAFE conversion?
The valuation cap sets the maximum company valuation at which the SAFE converts. If the next-round valuation exceeds the cap, the investor converts at the cap price rather than the higher valuation, receiving more shares. If the next-round valuation is below the cap, the SAFE converts at the lower price as normal.
What dilution do founders typically see after SAFE conversion?
Founders typically see between 10 and 25 per cent dilution from a single SAFE round, depending on the size of the raise, the valuation cap and whether a discount applies. Multiple stacked SAFEs can push total dilution above 30 per cent before the priced round closes.
Should founders model SAFE conversion before signing?
Yes. Founders who model SAFE conversion before signing understand exactly how much equity they will own after the priced round. Running the maths on at least two valuation scenarios — upside and downside — prevents surprises and ensures the terms are intentional rather than accepted by default.
The maths behind SAFE conversion scenarios are not optional knowledge for founders — they are the foundation of every cap table decision. Founders who run the numbers, model the downside and account for every SAFE on the table make informed choices. Those who leave it to chance discover that the cap table tells a story they did not author. For hands-on help modelling your round, Apply for pre-seed funding and we will run the numbers with you.
