Pre-money valuation is what a company is worth immediately before it takes in new investment. Post-money valuation is that figure plus the money raised: the company’s value the moment the round closes. The two are separated by exactly the size of the round, and the distinction decides what percentage of the company the new investors own.

The relationship is a single equation: post-money = pre-money + investment. Everything else (price per share, founder dilution, the size of an option pool) follows from which valuation a term sheet is quoting and how the share count is built around it. This guide covers both definitions, the formula that links them, a worked Series A example, and the places the pre/post distinction quietly changes the outcome.

The short version:

  • Pre-money is the company’s value before the new investment goes in. It sets the price per share the round pays.
  • Post-money is pre-money plus the amount raised. It sets the new investor’s ownership percentage.
  • The link: post-money = pre-money + investment, always.
  • Ownership: new investor % = investment ÷ post-money valuation.
  • Why it matters: quoting the same number as “pre” or “post” changes ownership by the full size of the round, so every term sheet should state which one it means.

The two definitions

A financing round prices the company at a point in time, but there are two points worth naming, and they sit on either side of the wire transfer.

Pre-money valuation is the agreed value of the business before the new money arrives. It is the number founders and investors actually negotiate, because it answers the real question: what is the company worth as it stands today, on its current cap table, before this round’s cash is added.

Post-money valuation is the value after the investment lands: the pre-money figure with the new cash added on top. It is the headline number most rounds are described by (“raised at a $24,000,000.00 post-money”), because it is the denominator that sets ownership.

Both describe the same round. They differ by exactly the amount raised, which is why a single round can be quoted two different ways without anyone being wrong, and why the two sides have to agree on which one a term sheet means.

The formula that connects them

There is really one identity and one consequence.

The identity:

Post-money valuation = Pre-money valuation + Investment

Rearranged, it also gives the pre-money figure from a headline post-money number: pre-money = post-money − investment.

The consequence is ownership:

New investor ownership % = Investment ÷ Post-money valuation

Ownership is always measured against post-money, because once the money is in, the investor owns a slice of the larger, post-investment company. Existing shareholders keep the rest and are diluted by the same proportion. (For the full mechanics of how that dilution lands on each holder, see startup dilution.)

Two corollaries are worth keeping in mind. Post-money can also be derived from the round and the stake (post-money = investment ÷ investor’s %), which is exactly how a “we’ll take 20% for $5,000,000.00” conversation backs into a $25,000,000.00 post-money. And pre-money, not post-money, is what sets the price per share: the per-share price is the pre-money valuation divided by the fully-diluted share count before the round.

Worked example: a Series A

A company raises a Series A on these terms:

  • Pre-money valuation: $18,000,000.00
  • Investment (raise): $6,000,000.00

Step 1: post-money valuation.

Post-money = $18,000,000.00 + $6,000,000.00 = $24,000,000.00

Step 2: the new investor’s ownership.

Investor % = $6,000,000.00 / $24,000,000.00 = 25.0%

The new investor owns 25.0%; existing shareholders are left with 75.0%, diluted pro-rata from the 100.0% they held before.

Step 3: the per-share view. Suppose the company has 9,000,000 fully-diluted shares before the round. The price per share is set off the pre-money valuation:

Price per share = $18,000,000.00 / 9,000,000 = $2.0000
New shares      = $6,000,000.00 / $2.0000   = 3,000,000
Total shares    = 9,000,000 + 3,000,000      = 12,000,000
Investor %      = 3,000,000 / 12,000,000      = 25.0%

Both routes land on 25.0%: the percentage from the valuation math and the percentage from the share-count math agree, which is the check that the round is modeled consistently. The share count is where most errors hide (an unallocated option pool or an unconverted SAFE left out of the denominator moves the price per share), and that mechanic is covered in full in price per share: how to calculate it.

Why the distinction changes your ownership

Because ownership is measured against post-money, quoting the same headline number as “pre” or “post” shifts the split by the entire size of the round.

Take the example above with the labels swapped. A $24,000,000.00 valuation read as post-money gives the investor 25.0% for their $6,000,000.00. The same $24,000,000.00 read as pre-money makes post-money $30,000,000.00, and the investor’s stake drops to $6,000,000.00 ÷ $30,000,000.00 = 20.0%. One word, “pre” or “post,” moved five points of the company. That is why a valuation quoted as only “$24M” is incomplete: the figure has to be labeled pre-money or post-money before any ownership calculation can be trusted.

The option pool is the other place the distinction bites. Investors often require the pool to be expanded as part of the round and sized against the post-money count, with the new shares carved out of the pre-money valuation. The effect is that the pool top-up dilutes existing shareholders, usually the founders, rather than the incoming investor. The headline valuation can look generous while the effective pre-money, after the pool, is materially lower. Modeling the pool inside the cap table is the only way to see the real number.

Pre-money and post-money in SAFEs

The same two words define the most common early-stage instrument. A pre-money SAFE sets its valuation cap on a pre-money basis, so when several convert together, they dilute each other and the final ownership is not knowable until the round prices. A post-money SAFE, the version Y Combinator standardized in 2018, sets its cap on a post-money basis, which fixes the holder’s ownership percentage regardless of how many other SAFEs convert. The trade-off is that all of that certainty for investors pushes the dilution onto founders, and stacked post-money SAFEs can remove more of the company than founders expect before the priced round even arrives.

A “post-money valuation cap” is therefore not the same promise as a pre-money cap. The label on the cap controls who absorbs the dilution from every other convertible in the stack, which is why the pre/post distinction matters as much on a SAFE as it does on a priced round.

Common mistakes

  • Quoting a valuation without saying pre or post. The single most common source of term-sheet confusion. A term sheet should state which one it means, because the gap is the full size of the round.
  • Calculating ownership against pre-money. Ownership is investment ÷ post-money. Dividing by pre-money overstates the investor’s stake.
  • Forgetting the option pool sits inside pre-money. A required pre-money pool expansion lowers the effective pre-money valuation and dilutes founders, not the new investor.
  • Mixing pre and post inputs in the same calculation. Price per share uses pre-money valuation and pre-money shares; ownership uses post-money. Crossing them produces numbers that do not reconcile.

This article is general information about startup valuation and equity modeling, not legal, tax, or investment advice. Round terms are negotiated and fact-specific, so confirm any term sheet and cap-table treatment with your counsel and financial advisors before relying on a model.

Frequently asked questions

What is the difference between pre-money and post-money valuation?

Pre-money valuation is what a company is worth before a new investment; post-money valuation is the pre-money figure plus the amount raised. They differ by exactly the size of the round, and the new investor’s ownership percentage is measured against the post-money valuation.

How do you calculate post-money valuation?

Add the investment to the pre-money valuation: post-money = pre-money + investment. A $18,000,000.00 pre-money round raising $6,000,000.00 has a $24,000,000.00 post-money valuation. Post-money can also be found from the stake taken, as investment ÷ investor’s ownership percentage.

Does pre-money or post-money determine my ownership?

Post-money determines the new investor’s ownership percentage: investment ÷ post-money valuation. Pre-money determines the price per share the round pays, by dividing the pre-money valuation by the fully-diluted share count before the round. Both are needed to model a round correctly.

Is a higher pre-money valuation always better for founders?

Not necessarily. A higher pre-money valuation reduces dilution for a given raise, but round structure often matters more. An option-pool top-up taken out of pre-money, a larger raise, or a participating liquidation preference can outweigh a higher headline number. The comparison has to be modeled on the cap table, not read off the term sheet.

What is a post-money valuation cap on a SAFE?

It is a valuation cap measured on a post-money basis, used by the standard post-money SAFE. It fixes the SAFE holder’s ownership percentage regardless of how many other SAFEs convert in the same round, which shifts the dilution from other convertibles onto the founders rather than spreading it across holders.

The bottom line

Pre-money and post-money are two views of one round: the value before the money, and the value after. Post-money = pre-money + investment, ownership is measured against post-money, and price per share is set off pre-money. Get those three straight and most valuation confusion disappears. The complications that remain (option pools carved out of pre-money, SAFEs that fix their percentage post-money) are real, but they are modeling questions, not definitional ones.

Waterfalls has a fundraising mode that models a priced round directly: enter the pre-money valuation and the raise, and it returns the post-money valuation, the price per share, the new shares issued, and every stakeholder’s ownership and dilution before and after, for priced equity rounds. It is a modeling tool, not a system of record, and it does not host your official cap table.