For the model used here, new-investor ownership equals the investment divided by pre-money plus investment. Without convertibles or a pool increase, raising $4M at a $16M pre-money sells 20%. A founder who held 60% retains 48%: a loss of 12 percentage points, or 20% relative dilution.

The calculator’s pre-money includes converting securities and the pool top-up. If your term sheet uses a different capitalization definition, the same headline valuation can produce a different result.

In the simple example, a new 10% unallocated pool is created before the $4M investment. New investors still take 20%, leaving the founders with 70%. Two equal founders retain 35% each.

The pool field is a target percentage after closing, not an extra percentage to subtract. An existing pool is carried forward and topped up only when necessary; the model never cancels options. In the exit module, unallocated options receive no payout unless you select the assumption that they have all been granted.

Add each instrument inside the priced round where it converts. All instruments in that round convert together. The calculator compares the cap price with the discounted round price and uses the lower price. A cap of zero disables the cap; a discount of zero means no discount.

For example, a $500K post-money SAFE with a $10M cap implies 5% before the new round and its pool increase when the cap controls. A lower financing price can produce more shares. A pre-money cap uses the existing share base and optionally the new pool; it excludes the other converting securities. Confirm the pool setting against the agreement.

A $500K note at 8% simple annual interest over 18 months converts $560K. The model treats that full balance as the note’s 1x preference after conversion. Agreements can treat interest differently.

Reference: Y Combinator’s SAFE documents and User Guide. This model also permits custom cap-plus-discount terms; that does not mean they are a standard YC form.

Under 1x non-participating preferred, an investor receives its preference or converts to common, whichever pays more. With participating preferred, it receives its preference and also shares in the remaining proceeds. Here, all preferred holders rank equally and participation is uncapped.

For example, an investor puts in $5M for 20%, with no option pool. At a $20M exit, a 1x non-participating investor receives $5M and founders receive $15M. At a $50M exit, that investor converts and receives $10M.

Enter the proceeds available to equity after debt and transaction costs. Starting “other holders” are modeled as common shares. To represent an earlier preferred investment, begin before that investment and enter it as a priced round.

Reference: Cooley GO: Preferred Stock.

It does not model anti-dilution adjustments, pro-rata exercise, warrants, dividends, tax, vesting, exercise costs, seniority between preferred classes, preference multiples or capped participation. It assumes all listed SAFEs and notes convert at their assigned round; an exit before conversion needs a different model.

For example, a round with a lower modeled share price triggers a down-round notice, but the model will not issue additional shares under an earlier investor’s anti-dilution clause. This is an illustrative planning tool, not a legal cap table. Check the actual terms and capitalization definitions before relying on its results.

“Compare a second scenario” makes an independent copy. For example, lower the pool target from 15% to 10% in Scenario B and compare the founder ownership and exit payout while keeping the same exit proceeds.

Excel and PDF include both scenarios, inputs, results and assumptions. Excel contains calculated values rather than a second calculation engine. “Copy for Sheets” copies the active cap table. Save a scenario file to resume later or use the shared link to reopen the included numbers. The calculator does not automatically save your work.