Costs of the Apollo lunar effort, adjusted for inflation to 2019 dollars using the NNSI and relative GDP share. Detailed numbers are available in the source data. Source data.

To summarize: the entire lunar effort (with robotic missions and Gemini included) would cost $288 billion in today's dollars. If the U.S. prioritized a space project financially the same way it did with Apollo the 1960s, the nation would have to spend $702 billion to account for an equivalent share of GDP.

What costs should we consider as part of Apollo?

Since no accounting effort is wholly objective, I attempted to note every subjective decision I made regarding what to count, when, and where, via per-cell comments in the Excel spreadsheet version of the source data.

I took a generous interpretation of Apollo-related costs: if it fed into the lunar effort, or was likely to, I included it as part of Apollo. This occasionally means that there are small discrepancies between my annual project sums and those reported by NASA (mine tend to be slightly larger). I also included spending on the Saturn project pre-dating the actual start of Project Apollo, as those were used primarily for the lunar effort. My totals for launch vehicle development ($9.4 billion in then-year dollars) are therefore slightly higher than those reported by NASA ($9.1 billion).

I also attempted to normalize costs across accounts in the summary tables of the source data. NASA's accountants frequently changed their internal accounting practices for Apollo, making it otherwise hard to compare spending year-to-year. For example, in the very early 1960s, the costs of the Saturn rocket engine development were grouped with the costs of Saturn rocket engine procurement. In later years, procurement costs for the engines were included with the direct costs of the rocket, and development was considered separately. I account for this in my summary tables, and further acknowledgments of these sorts of minutiae are included in the Excel spreadsheet.

A common cost discrepancy ($25 billion vs. $20 billion) is explained by the following. Throughout the 1960s and 1970s, NASA's budget was divided into three primary accounts: Research & Development (R&D), Construction of Facilities (CoF), and Administrative Operations (AO)—later renamed Research & Program Management (R&PM). Nearly all of the detailed cost data we have for Apollo comes from the R&D accounts, which paid for obvious things like the development and production of Apollo spacecraft, the Saturn V launch vehicle, mission operations, and project integration. Combined, these amount to $20.6 billion and are the source of the $20 billion figure commonly cited online.

Indirect costs should not be discounted, however. These include the costs to build Apollo's enabling infrastructure, including the space centers currently known as Johnson, Kennedy, and Stennis. Without these facilities and their attendant staff, Apollo obviously would not have happened. These data are harder to suss out from congressional budget justifications, and I instead rely on two internal reports prepared for Congress from NASA's financial office which breaks down facilities and overhead costs from FY 1961 - FY 1973. Facilities and overhead costs for Apollo were included in (aptly-named) "Construction of Facilities" and "Administrative Operations" and were considered separately during the congressional appropriations process.

The sum of the direct and indirect costs accounts for the $25.8 billion number that closely matches the total cost reported to Congress in 1973. However, I argue that this undercounts the total U.S. investment in Apollo, as there were other efforts pursued in service of the lunar goal throughout the 1960s. In particular, Gemini refined operations and rendezvous in low-Earth orbit in service of Apollo. The robotic lunar programs in the 1960s also mapped the lunar surface and provided crucial ground-truth in advance of astronauts. Just because they weren't included in the Apollo budget account in NASA's ledgers doesn't mean the money wasn't spent. I elected to include them as "related programs" and incorporated them into the total cost when speaking of the "lunar effort."

You may disagree with my subjective accounting decisions. It is for that reason that I included the raw data for each fiscal year as presented in the congressional budget justifications. You can reconstruct or re-interpret these data to your heart's content.

Why you shouldn't use the "Apollo Program Budget Appropriations" data source

The NASA History Office website hosts a detailed cost breakdown for Apollo, by year, which first appeared in the 2000 publication, Apollo By the Numbers: A Statistical Reference, by Richard Orloff, which itself compiles data first published the 1970s from the book, The Apollo Spacecraft: A Chronology, volumes I through IV.

Don't use this as a source. It contains fundamental errors, significant omissions, and presents an inaccurate picture of Apollo funding. It undercounts direct costs by nearly $1 billion and omits all indirect costs.

First, the data presented as "Apollo Program Budget Appropriations" are not actually appropriations. Instead, it is a mix of proposed spending (FY 1962, FY 1973) and contracted spending, or obligations for all other years. Congressional appropriations are not included at all. As a reminder: NASA requests funds via annual budget justifications submitted Congress. Congress then appropriates funding based on those requests. NASA obligates these funds in the form of contracts, eventually paying them out as expenditures.

Second, the table lists significant spending on "orbital reentry tests," "biomedical tests," and "high-speed reentry tests" in FY 1962. As far as I can tell, these are phantom expenditures. After doing some digging, I found that these numbers come from the FY 1962 budget request (see the previous paragraph) and don't represent actual money spent. These tests were probably incorporated into Project Gemini, which began after the FY 1962 budget estimates were prepared in early 1961.

Third, there are significant omissions for programs before FY 1964. It should be a warning sign to any attentive reader that this source claims that $0 was spent on the Saturn I rocket before FY 1964—an impressive claim of fiscal efficiency considering the rocket first launched in 1961.

Fourth, the annual values for "NASA Total" only include the space agency's R&D account. As discussed previously, it excludes the Construction of Facilities and Administrative Overhead accounts and thus understates NASA's annual budgets.

Fifth, it contains a fundamental arithmetic error for NASA's total budget from 1960 - 1973. It should be $41 billion given the numbers provided, not $56 billion as claimed.

Sixth (and finally), it makes no attempt to normalize annual accounting changes. This is why there are columns with a single value for items like "Saturn I-C," "Spacecraft," and "Flight Modules (the CSM and LM). As these are presented without context, it is impossible to compare one year to another.

There are more reasons, but is it worth further belaboring a point? Don't use this source.

Why this matters

Apollo demanded precision and attention to detail to succeed as it did. As space advocates and supporters, the least we can do is to maintain similarly high expectations for historical fidelity, which is why I find sloppy and inaccurate Apollo cost accounting so frustrating. There is no value, either historically or politically, to understating the resources required to succeed in that endeavor.

How much was spent on Apollo, and when, is relevant as NASA has once again been directed to return humans to the Moon. To properly evaluate the seriousness of this directive, it makes sense to compare its spending proposals to the one data point we have for a successful human lunar mission. How much money did it take to do it the first time? How was it spent? And, perhaps most importantly, when did the money show up?

To date, the White House has proposed an additional $1.6 billion for Project Artemis, on top of the $5 billion spent annually on the Space Launch System, Orion, and related ground systems. Compared to Apollo, this is a relatively modest investment. Looking forward, we should expect significant increases in spending associated with an accelerated lunar effort or adjust our expectations accordingly.

Resources

"How much did the Apollo program cost?"

This page summarizes the costs of Apollo and includes charts highlighting the annual costs of major Apollo systems such as the Command and Service Module, the Lunar Module, and the Saturn V.

Project Apollo Cost Data Set (Excel spreadsheet)

Comprehensive Project Apollo annual cost data, non-inflation adjusted dollar amounts, program-by-program cost breakdowns, construction costs, and relative GDP adjustments are available to download as an Excel spreadsheet or to view as a Google spreadsheet.

NASA Budget Estimates & Documentation

A public Google Drive folder which includes NASA budget submissions to Congress, including every one between 1960 and 1973 and additional Apollo budget documents.