Five $100K SAFEs at a $5M Cap Sell 10% of a Startup—Not 2%

A $100,000 SAFE at a $5 million post-money valuation cap can look like a small financing. In Y Combinator’s math, it represents 2% ownership. Sign five of those SAFEs at the same cap and the company has sold 10%. The checks are small individually, but the ownership adds.^{1, 3}

IN BRIEF

For YC’s post-money valuation-cap SAFE, ownership sold equals investment divided by the post-money cap. Five $100,000 SAFEs at a $5 million cap therefore add up to 10%, not 2%. The SAFE holders can then be diluted by the new money and a new or increased option pool when the company raises a priced round.^{1, 2}

The SAFE math before the priced round

$100K

Each check¹

Illustrative YC example using a post-money valuation-cap SAFE.

$5M

Post-money cap¹

The valuation cap used for each SAFE in YC’s example.

10%

Five SAFEs^{1, 3}

Five $100K post-money SAFEs at a $5M cap, before later priced-round dilution.

How equal post-money SAFEs accumulate at a $5M cap^{1, 2}

SAFEs signed	Total invested	Ownership represented
1 × $100K	$100K	2%
2 × $100K	$200K	4%
3 × $100K	$300K	6%
5 × $100K	$500K	10%

The valuation cap turns dollars into an ownership percentage

For a YC post-money valuation-cap SAFE, the basic ownership calculation is investment divided by the post-money valuation cap. A $100,000 investment divided by $5 million is 2%. YC designed the post-money form so founders and investors can calculate that ownership before a later equity financing converts the SAFE into shares.²

That transparency is the important part. A founder does not need to wait for a Series A to discover that five separate 2% promises add up to 10%. The cap table can track the running total while each SAFE is still a convertible instrument rather than issued stock.^{2, 1}

Post-money SAFEs are additive, not mutually dilutive

YC says post-money SAFEs at valuation caps are additive because the other SAFEs are already included in the company-capitalization denominator. One SAFE does not reduce the percentage represented by another. This is why the five-check example lands at 10% rather than leaving every investor with only a slice of the original 2%.¹

The priced round adds another layer of dilution

The fixed SAFE percentage is not the founder’s final post-round cap table. YC’s calculator explains that new money in the priced round and a new or increased option pool dilute both founders and post-money SAFE holders. Those two items sit outside the SAFE’s earlier capitalization calculation and enter when the priced round is modeled.¹

What is fixed at the SAFE stage and what changes later^{1, 2}

Stage	What the founder can know	What can still change
Post-money capped SAFE	Ownership represented by each capped SAFE using investment ÷ cap	Discount or MFN instruments use different mechanics
Additional capped SAFEs	Their ownership percentages can be added to the running total	New SAFEs add more ownership sold
Priced equity round	SAFE conversion happens automatically under the instrument terms	New-money financing and an increased option pool can dilute existing holders

A SAFE is not stock until it converts

YC describes a SAFE as an instrument that converts into preferred stock when the company raises a priced equity financing. That distinction matters when reading a cap table. The SAFE represents an ownership claim under its terms before the holder becomes a stockholder, which is why modeling the conversion is part of understanding the next round.^{2, 1}

Before signing the next SAFE, keep these numbers together^{1, 2}

The amount of every outstanding post-money valuation-cap SAFE.
The valuation cap attached to each SAFE rather than only the latest one.
The cumulative ownership represented by all capped SAFEs issued so far.
The option-pool increase and new-money amount expected in the next priced round.

This is why a cap table becomes more than a list of names. The cap-table software pricing analysis shows how vendors expand from a free ownership record into modeling, valuation and reporting work. The arithmetic becomes valuable before the company is large because every new financing term changes the ownership story.

The 10% example is not a universal startup outcome. It applies to five $100,000 post-money valuation-cap SAFEs at a $5 million cap. Different SAFE forms, discounts, MFN terms, priced-round valuations and option-pool negotiations can produce different results. The useful habit is simpler: keep a running ownership calculation before another check gets signed.^{1, 2}

Sources and methodology

Sources checked September 27, 2026. Dates and periods for individual figures are stated beside them.

Y Combinator: SAFE conversion calculator ↗Accessed 2026-09-27
Y Combinator: the SAFE and how post-money ownership works ↗Accessed 2026-09-27
Y Combinator: SAFE vs. convertible note vs. priced round ↗Accessed 2026-09-27

Scope and assumptions

The 10% result applies to the stated YC post-money valuation-cap SAFE example and is not a prediction for every SAFE financing.

Discount SAFEs, MFN SAFEs, pre-money instruments and negotiated priced-round terms can follow different mechanics.

This is an educational explanation of published instrument mechanics, not legal, tax or personalized fundraising advice.

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