Case &ContrastFree calculators

Finance & equity

Investment Dilution & Ownership Calculator

Calculate the new investor share and one existing owner’s percentage after a primary investment at an entered pre-money valuation.

73 / MODEL ONE PRICED ROUND

Your numbers.
A clearer decision.

Free to use. No signup.
Inputs stay in this browser.

Starting values are illustrative. Use your own costs, rates and assumptions.

INPUT GROUP 01

Priced round assumptions

Check the assumptions before acting on a result.

Read the method and example

YOUR CALCULATION

One new primary investment dilutes the existing ownership proportionally.

Post-money valuation

$5,000,000.00

New investor ownership

20.00%

Existing holders combined after round

80.00%

Your modeled ownership after round

48.00%

Your ownership decrease (percentage points)

12

Keep the calculation

Saving is optional and stays on this device. Unsaved edits are not kept when you leave. CSV includes every input and the current results.

Illustrative inputs loaded. Replace them with your own assumptions.

How the investment dilution & ownership calculator works

Post-money valuation equals pre-money valuation plus the new primary investment. The new investor percentage is investment divided by post-money valuation. Pre-money valuation must be positive; a zero investment leaves existing ownership unchanged.

All existing holders together retain pre-money divided by post-money valuation. Your modeled post-round percentage is your current percentage multiplied by that retained fraction. The decrease is reported in percentage points. These ratios use the entered values before currency display rounding; they are ownership arithmetic rather than proceeds payable to an existing holder.

The model assumes a single primary priced round and proportionate dilution of existing holders. It excludes new option pools, SAFE or note conversion, secondary sales, preferences, fees and anti-dilution provisions. It does not appraise the company or replace the capitalization definitions in the financing documents.

Worked example

A 4,000,000 pre-money valuation plus 1,000,000 new investment gives 5,000,000 post-money. The new investor owns 20% and existing holders retain 80%. An owner starting at 60% becomes 48%, a decrease of 12 percentage points. With no new investment, that owner remains at 60%.

Sources and assumptions

The source material explains the underlying calculation or pricing structure. Entered prices, costs, schedules and scenario choices are your assumptions; this tool does not obtain supplier quotes or predict actual results.

  • Office Lease vs Ownership Cash Cost

    Compare a common occupancy horizon with entered lease costs, financing, ownership costs and an explicit exit sale.

  • Business Loan Repayment

    Build an end-of-month repayment schedule with monthly cent-rounded interest, a deducted upfront fee and an adjusted final payment.

  • Invoice Aging & Collections

    Enter five due-date aging buckets and your collection assumptions. See the overdue total and an oldest-first review table without entering customer details.

  • Budget vs Actual Variance

    Compare one period of revenue, labor, materials and other costs with its budget. Separate a spending variance from its opposite effect on modeled profit.

Calculation methods, testing and sources · Practical calculation guides