How to Build a Pre-Seed Cap Table in a Spreadsheet: A Step-by-Step Model First-Time Founders Can Copy

At pre-seed you can build a working cap table in a spreadsheet. List founders and their shares, add any option pool, then record each post-money SAFE with its cap and amount as a future claim on ownership. The key move is modeling on a fully diluted basis, so the SAFEs and the pool show their dilution before the priced round makes it real.

Cap-table software is worth paying for eventually, but not at pre-seed. Before you have preferred stock, vesting option grants, and a lead investor asking for reports, a Google Sheet does everything you need, and it forces you to actually understand your own ownership instead of trusting a dashboard. The founders who get burned at their priced round are almost always the ones who never built the sheet themselves and did not see the SAFEs and the option pool coming.

This is the exact structure to build, column by column, with the SAFE and option-pool math that trips up first-time founders. Copy it, put your own numbers in, and you will understand your cap table better than most founders do at Series A.

Why a spreadsheet is enough at pre-seed

A cap table just answers one question: who owns what, on a fully diluted basis, after every event so far. At pre-seed the cast is small. You have founders, maybe an option pool, and a stack of SAFEs. There is no preferred stock yet, because SAFEs are not equity until they convert. That simplicity is exactly why a spreadsheet works, and why building it by hand is the best fundraising education you can give yourself.

The moment to graduate to software is when you close a priced round. Then you have preferred shares with rights, option grants with vesting schedules, and legal filings that need to match your records exactly. Until then, a sheet you understand beats software you do not. Cap-table platforms like Carta explain the core concepts well, but you do not need to pay for one to model a pre-seed.

Step 1: Set up founder shares

Start with a round number of authorized founder shares. Ten million is common and makes the percentages easy to read. If two founders split evenly, that is 5,000,000 each. Your spreadsheet's first columns are simple.

The share count itself is arbitrary; what matters is the percentages and how they change. Set your total shares once and let every later event either issue new shares or reserve them, recalculating the percentages off the new total. Build the percent column as a formula dividing each holder's shares by the grand total, so it updates automatically as you add rows.

Step 2: Add the option pool

Most pre-seed founders create an option pool to hire early employees. The standard starting point is around 10 percent of the fully diluted company, sized to cover grants until your next round. The critical modeling question is not the size but the timing, because whoever the pool dilutes depends on when it is created.

If you set aside a 10 percent pool now, before any SAFE converts, add 1,111,111 reserved shares so the pool is 10 percent of the new 11,111,111 total. Every founder's percentage drops proportionally. Add a row for the pool and label it clearly as reserved, whether or not the options are granted yet, because on a fully diluted basis reserved-but-ungranted options still count against everyone else.

Here is the trap. At your priced round, investors typically want the pool created or topped up out of the pre-money, which means it dilutes founders and not the new investor. That is the option pool shuffle, and it quietly costs first-time founders several points of ownership. Model it both ways in your sheet so you can negotiate with the number visible. The full mechanics are in the option pool shuffle.

Step 3: Record each post-money SAFE

This is where first-time founders make the biggest errors, because a post-money SAFE does not behave like intuition suggests. A post-money SAFE fixes the investor's percentage of the company as of conversion. You calculate it as the SAFE amount divided by the post-money valuation cap.

Suppose you raise on three SAFEs, all at a $6M post-money cap: $300K, $150K, and $50K. The ownership each locks in is simply its amount over $6M.

Add one row per SAFE with amount, cap, discount if any, and flags for MFN or pro rata. The uncomfortable truth of post-money SAFEs is that the dilution from these instruments falls entirely on you, not on earlier SAFE holders. Each new SAFE you sign dilutes the founders and the option pool, while every prior SAFE investor keeps their locked percentage intact. That asymmetry is the single most important thing to understand about the instrument, and it is worked through in detail in how a post-money SAFE converts at your priced round. If your SAFEs sit at different caps, the cap and discount interact with MFN clauses in ways covered in SAFE valuation cap and discount.

Step 4: Model the fully diluted picture

Now combine everything. Before the priced round, your founders still legally hold 100 percent of the issued common stock, because SAFEs have not converted. But that number lies. Your real position is the fully diluted view, where the option pool and all the SAFEs are counted as if they already converted.

With a 10 percent pool and 8.33 percent of committed SAFEs, the founders' fully diluted stake is not 90 percent and not 100 percent; it is what remains after both claims. A clean way to model this in the sheet is to keep two percentage columns: one for issued common today, and one for fully diluted, which nets out the pool and the as-converted SAFEs. Always make decisions off the fully diluted column. This is the same discipline that drives the round-by-round math in cap table math for first-time founders.

Step 5: Add the priced round to see where you land

The pre-seed sheet becomes predictive when you tack on a hypothetical priced seed. Add the new investor's money at a chosen pre-money, convert the SAFEs at their caps, and place the option pool per the term sheet. The founders' final percentage is what falls out. Watching that number move as you change the seed pre-money or the pool size teaches you more about dilution than any explainer, and it tells you what milestone your pre-seed has to buy so the seed step-up is defensible. That milestone framing connects directly to how much to raise at pre-seed, because the round size and the dilution are two ends of the same equation.

A full worked example, formation to seed

Put every step together with one set of numbers so you can see the founders' stake move.

Two founders start on 10,000,000 shares, 50/50. They add a 10 percent pre-conversion option pool, dropping each to 45 percent on a fully diluted basis. They raise $500K on post-money SAFEs at a $6M post-money cap, which commits 8.33 percent to investors. On the pre-priced sheet, the founders' fully diluted stake is now roughly 41.7 percent each, the pool holds about 9.2 percent, and the SAFEs hold 8.33 percent, all summing to 100.

A year later they raise a $2.5M seed at a $10M pre-money, a $12.5M post-money. Three things happen at once: the new investor takes 20 percent, the SAFEs convert at their cap, and the term sheet tops the option pool back up to 10 percent post-money out of the pre-money. Run that through the sheet and the two founders land near 30 to 32 percent each, down from 50 at formation.

The point of building this in your own sheet is that you can change any input, the SAFE cap, the pool size, the seed pre-money, and watch the founder line respond in real time. Free starting templates from sources like Y Combinator's document library give you the SAFE forms themselves, but the modeling sheet is worth building yourself so you understand every cell.

Common spreadsheet mistakes to avoid

A few errors show up again and again. Founders track issued common stock instead of fully diluted ownership, and get shocked when the SAFEs convert. They forget the option pool counts before it is granted. They model a pre-money SAFE percentage when they actually signed a post-money SAFE, which understates their dilution. And they let the total-shares figure drift so the percentages stop summing to 100. Build one grand-total cell that every percentage references, and sanity-check that the column always sums to exactly 100 percent after each event.

One more habit saves you real pain: version the sheet. Every time you sign a SAFE or grant options, save a dated copy before you edit, and add a short note recording the amount, cap, and date of the event. When a future investor's lawyer runs diligence, or when you migrate to cap-table software at your priced round, a clean event-by-event history is what makes the transition painless. A cap table that only shows today's state, with no record of how it got there, forces you to reconstruct months of decisions from memory at the worst possible moment.

From spreadsheet to strategy

Building the sheet is not busywork; it is how you make every fundraising decision with the ownership consequence in front of you. Once you can see what a lower cap, a bigger pool, or one more SAFE does to your final stake, you negotiate from knowledge instead of hope. That is the whole point of doing the math yourself before an investor does it for you. When you are ready to connect this cap-table view to the rest of the raise, from sizing the round to reading the term sheet, The Funding Framework walks a first-time founder through the full sequence with the numbers worked out.

Build the sheet once, keep it current after every SAFE, and you will never be surprised by your own cap table.