# Startup equity calculator: see the dilution by round.

Model a simple cap table, one SAFE and four-year vesting with a one-year cliff — free, no sign-up.

Page: https://saascode.ai/tools/startup-equity-calculator

## How to use

1. Enter initial holders and shares, then optional SAFE investment, post-money cap and discount. Zero investment disables it.
2. Enter up to six priced rounds in order and a separate vesting grant with whole elapsed months.
3. Inspect each cap table and formula, then export JSON for review with your advisors.

## Scope

Educational model only — not financial or legal advice. Your signed financing documents govern conversion and vesting. Review the cap table with qualified advisors.

## References

- [Y Combinator SAFE documents — checked 2026-10-09](https://www.ycombinator.com/safe)

## Equity formulas and assumptions

Educational model only — not financial or legal advice. Your signed financing documents govern conversion and vesting. Review the cap table with qualified advisors. Single SAFE; pre-money includes converted shares. Vesting grant is separate.

| Calculation | Formula / limit |
| --- | --- |
| SAFE valuation | E = min(cap, pre-money × (1 − discount)); ignore zero cap |
| SAFE ownership | q = investment / E, before new money |
| SAFE shares | initial shares × q / (1 − q) |
| Theoretical round dilution | investment / (pre-money + investment), before whole-share rounding |
| Vesting | 0 before month 12; grant × min(months,48)/48 thereafter |
| Excluded | Pools, other SAFEs, notes, fees and pro-rata rights |

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## FAQ

### Is it free, and is an account required?

Free, no sign-up. Editing and exports run in your browser without an AI model. Usage events contain only the tool name and action. Drafts last while the page is open; download before leaving.

### What SAFE model is used?

One SAFE before round one. E = min(cap, pre-money × (1 − discount)); ignore cap if uncapped. q = investment / E; SAFE shares = initial shares × q / (1 − q). Pre-money includes converted SAFE shares. Investment must be below E.

### Is cap and discount the standard YC SAFE?

No. This configurable model chooses the favorable cap or discount. YC publishes separate forms. Capitalization definitions, pools, other SAFEs and pro-rata rights can change results. This is an educational model, not a contract interpreter.

### How do rounds dilute holders?

Price/share = pre-money / shares before new money. New shares = investment / price. Theoretical new investor stake = investment / (pre-money + investment). Emitted shares are rounded down; actual ownership is recalculated from whole shares and display percentages sum to 100%.

### How does vesting work?

Monthly over 48 months with a 12-month cliff: zero before month 12, 25% at month 12, then grant × min(months,48)/48. This grant is separate from the cap table and adds no shares to it.

### What is excluded?

Multiple or pre-money SAFEs, note interest, pool increases, fees, pro-rata rights, acceleration. Newly issued shares are rounded down and the fraction discarded; ownership uses emitted whole shares and displayed percentages sum to 100%. Signed documents and qualified advisors govern financing.