SAFE Conversion Math Explained With Examples
A SAFE feels simple when you sign it: money in today, shares later. The "later" part is where founders get surprised. When your priced round arrives, every SAFE converts at once, and the math decides how much of the company you still own. This guide walks through that math step by step, with worked examples you can copy into a spreadsheet.
Key takeaways
- With a post-money valuation cap, a SAFE investor's ownership is roughly the investment divided by the post-money cap.
- With a discount, the conversion price is the priced round's price times (1 minus the discount).
- If a SAFE has both a cap and a discount, the investor usually gets whichever gives the lower price.
- SAFEs stack: each one you sign adds dilution that lands mostly on founders when the priced round closes.
- A simple conversion tracker keeps you from being surprised when your lead investor sends a pro forma cap table.
Many founders raise several SAFEs over a year or two: a small check from a friend, an accelerator investment, a few angels at a higher cap. Each one feels manageable on its own. The trouble is that nobody adds them up until the priced round, and by then the dilution is locked in.
This explainer is not about whether to use SAFEs or how to negotiate one. It is about the arithmetic: what happens to each SAFE on conversion day, and how to estimate your ownership in advance. With year-end approaching, it is a good moment to tally every SAFE you signed this year while the details are fresh.
A quick note: this is general information, not legal, tax or investment advice. SAFE documents vary, and small wording differences change the math. Ask your startup lawyer to confirm the exact terms and build the official pro forma cap table.
The three numbers every SAFE conversion uses
Almost every SAFE conversion depends on three inputs. Gather them for each SAFE before you do any math.
- The purchase amount: how much the investor paid.
- The valuation cap: the maximum valuation at which the SAFE converts. Most modern SAFEs use a post-money cap, which means the cap includes the SAFE money itself. Some older SAFEs use a pre-money cap, which works differently.
- The discount: a percentage off the price that new investors pay in the priced round, if the SAFE has one.
You also need one number from the priced round: the price per share the new investors pay. Your lead investor's term sheet and your lawyer's model will give you that.
Conversion with a post-money valuation cap
The post-money cap is the easiest case to estimate. The investor's ownership right after the SAFEs convert (but before the new money comes in) is roughly:
- Ownership = purchase amount divided by post-money cap.
Example 1: one capped SAFE
Jordan invests $500,000 on a SAFE with a $5 million post-money cap. Ownership is roughly $500,000 divided by $5,000,000, which is 10%. That 10% is measured just before the priced round's new money, so it will be diluted along with everyone else when the new investors buy their shares. (All figures are made up for illustration.)
Turning ownership into a price per share
To find the conversion price, divide the post-money cap by the company's capitalization as defined in the SAFE. In a post-money SAFE, that capitalization usually includes existing shares, outstanding options, the option pool and the converting SAFEs themselves. That is exactly why the ownership shortcut works.
Say the defined capitalization comes to 10,000,000 shares. The cap price is $5,000,000 divided by 10,000,000, which is $0.50 per share. Jordan's $500,000 converts into 1,000,000 shares, which is 10% of 10,000,000. The two methods agree.
Pro tip
If the cap is post-money and your SAFEs total $1 million on a $5 million cap, those SAFE holders will own about 20% before the priced round. That quick division is the single most useful habit for SAFE math. Do it every time you sign a new SAFE.
Conversion with a discount
A discount gives the SAFE investor a lower price than the priced round investors pay. The formula is:
- Discount price = round price per share times (1 minus the discount).
- Shares = purchase amount divided by discount price.
Example 2: discount only
Priya invests $200,000 on a SAFE with a 20% discount and no cap. The priced round sets a price of $2.00 per share. Priya's price is $2.00 times (1 minus 0.20), which is $1.60. Her $200,000 converts into 125,000 shares. (Made-up figures.)
A discount-only SAFE moves with the round price. If the company's valuation rises a lot before the round, the discount investor shares in that rise less than a capped investor would.
When a SAFE has both a cap and a discount
Many SAFEs have both. In that case, the investor usually gets whichever method gives the lower price per share, which means more shares.
- Calculate the cap price. Post-money cap divided by the defined capitalization.
- Calculate the discount price. Round price times (1 minus the discount).
- Pick the lower price. That is the conversion price for this SAFE.
- Divide the purchase amount by that price. The result is the number of shares the investor receives.
- Repeat for every SAFE. Each SAFE converts on its own terms, even if they all convert on the same day.
Example 3: cap and discount
Sam invests $300,000 on a SAFE with a $6 million post-money cap and a 20% discount. The defined capitalization is 12,000,000 shares, so the cap price is $0.50. The priced round sets $2.00 per share, so the discount price is $1.60. The cap price is lower, so Sam converts at $0.50 and receives 600,000 shares. If the round price had been only $0.55, the discount price would have been $0.44, lower than the cap price, and Sam would convert at $0.44 instead. (Made-up figures.)
Stacked SAFEs: the full picture before your round
The real surprise comes when several SAFEs convert together. Because post-money caps measure each investor's ownership against the company including all SAFEs, every new SAFE dilutes the founders and option holders, not the earlier SAFE holders.
Example 4: three SAFEs and a priced round
A startup has signed three post-money SAFEs: $250,000 at a $5 million cap (5%), $500,000 at an $8 million cap (6.25%) and $250,000 at a $10 million cap (2.5%). Together, SAFE holders own about 13.75% just before the priced round. Founders, staff and the pool share the remaining 86.25%. Then a lead investor buys 20% in the priced round. Everyone is diluted by that 20%, so SAFE holders end up with about 11% and the founders' group with about 69%. If the term sheet also adds a new option pool in the pre-money, the founders' share drops further. (Made-up figures, simplified.)
That last point matters. An option pool increase counted in the pre-money valuation dilutes existing holders, mostly founders. Depending on the SAFE wording, converting SAFEs may or may not share in that dilution, so ask your lawyer to model it.
SAFE conversion tracker template
Copy these columns into a spreadsheet and add one row per SAFE. The figures below are made-up examples.
| Investor | Amount | Post-money cap | Discount | Ownership at cap (amount / cap) | Notes |
|---|---|---|---|---|---|
| Angel A | $250,000 | $5,000,000 | None | 5.0% | Signed first quarter |
| Accelerator | $500,000 | $8,000,000 | None | 6.25% | Check program terms |
| Angel B | $250,000 | $10,000,000 | 20% | 2.5% | Discount may apply if round price is low |
Add a total row for the ownership column. That total is your best quick estimate of how much SAFE holders will own just before the priced round. Then apply the expected priced round dilution to see where you land.
Common mistake
Mixing up pre-money and post-money caps. A $5 million pre-money cap and a $5 million post-money cap produce different results, and older SAFEs or custom documents may use either. Read the definition section of each SAFE, and record the cap type in your tracker.
Another common mistake
Ignoring side terms. Some SAFEs include a most favored nation clause, pro rata rights or side letters that change the outcome. Keep copies of every signed SAFE and side letter in your data room so your lawyer can check them all at once.
Practical habits for founders raising on SAFEs
- Update the tracker the day you sign. Not at year-end, not before the round. The same day.
- Model the next round before you sign another SAFE. Ask: if we raise our priced round at a reasonable valuation, what will founders own? If the answer worries you, raise less or at a higher cap.
- Share the summary with your lead early. Investors will see your SAFEs in diligence anyway. Showing a clean tracker builds trust.
- Ask for a pro forma cap table. Before you sign a priced round term sheet, get a pro forma that shows every holder after conversion and new money.
- Get tax advice for your situation. Conversion itself is usually a legal and cap table event, but founders and investors may have tax questions, especially across borders.
Your SAFE math checklist
- Collect every signed SAFE and side letter
- Record amount, cap, cap type and discount for each
- Divide each amount by its post-money cap to estimate ownership
- Add up total SAFE ownership before the priced round
- Apply the expected priced round dilution and any pre-money pool
- Compare cap price and discount price for SAFEs with both
- Ask your lawyer for an official pro forma cap table
- Update the tracker every time you sign a new SAFE
Frequently asked questions
Why does the shortcut "amount divided by cap" work?
With a post-money SAFE, the cap is defined to include the SAFE money and the other converting instruments. So the investor's slice is fixed relative to that post-money number, and dividing the amount by the cap gives the ownership just before the new round money. Exact share counts still depend on the document's definitions.
What happens if there is never a priced round?
SAFEs usually include terms for other events, such as a sale of the company or a dissolution. In a sale, the investor may get either their money back or the value of their converted shares, depending on the document. Read those sections and ask your lawyer how they apply.
Can a discount-only SAFE be better for founders?
It can be, if your valuation rises a lot before the priced round, since the investor's price moves with the round. But uncapped SAFEs are less common and investors often push back. Model both versions before you agree.
Related reading
The bottom line
SAFE conversion math comes down to a few simple formulas: amount divided by post-money cap for ownership, round price times (1 minus the discount) for the discount price, and the lower of the two when a SAFE has both. The surprise is never the formula. It is the total, once every SAFE converts together.
Keep a tracker, run the numbers each time you sign, and ask for a pro forma before your priced round. Conversion day will then feel like confirmation of what you already knew.
