How Big Would Heaven Need to Be? A Population Geometry Thought Experiment

About 300,000 years ago, a human being stood on the Jebel Irhoud plateau in what is now Morocco. The forehead was low, the back of the skull flat — but the face would have looked familiar across a crowded subway car. In 2017, paleoanthropologist Jean-Jacques Hublin and his team published findings in Nature dating these fossils to approximately 300,000 years ago.^[1] They are the oldest confirmed remains of anatomically modern Homo sapiens.

Three hundred thousand years have passed since then. In that span, how many people have been born and died?

The Population Reference Bureau (PRB) — a U.S.-based demographic research organization — calculated in 2022 that approximately 117 billion humans have ever been born on Earth.^[2] Subtract the 8 billion currently alive, and roughly 109 billion people have already died.

109 billion. To feel the scale: it is about 14 times the entire current world population. If every person who ever lived joined hands in a single line, that line would encircle the Earth roughly 200 times — then dissolve into history.

So: if all 109 billion were admitted to heaven, how large would heaven need to be?

This article is a mathematical thought experiment. It does not advocate for or against any religious doctrine, and makes no claim about whether heaven exists.

INPUT

Variable 1: Cumulative Historical Deaths $N$

$$N = 1.09 \times 10^{11} \text{ people}$$

The PRB’s methodology works as follows: starting from an assumed baseline population at a fixed point in history, they multiply era-specific birth rates per thousand people to accumulate total births across all subsequent periods. Their baseline is 190,000 BCE, with an assumed initial world population of two people.^[2] This is more conservative than the paleoanthropological evidence (which points to ~300,000 BCE), but since population density was so low at the boundary, the choice of starting point has a negligible effect on the cumulative total.

This article uses the PRB’s 2022 single-point estimate, $N = 1.09 \times 10^{11}$. PRB itself acknowledges substantial uncertainty (±10–20%), but since the per-soul area variable $a$ spans several orders of magnitude, the uncertainty in $N$ has no meaningful effect on the conclusions.^[2]

Stance: central estimate.

Variable 2: Heaven Admission Rate $p$

$$p = 1.0 \text{ (universal salvation)}, \quad 0.33 \text{ (Christian share)}, \quad 0.10 \text{ (strict selectionism)}$$

Theology has no consensus on who gets in. This article runs three scenarios side by side.

• $p = 1.0$: Universalism — ultimately every human being is saved.
• $p = 0.33$: Approximates the global share of Christians (~31–33%), using Pew Research Center’s world Christianity survey as a reference.^[3]
• $p = 0.10$: A strict-selectionist reading, where only a small fraction of all who lived qualify.

Whose heaven, exactly? One thing is worth pausing on. The word heaven is sharpest in the Christian tradition, but the idea of an afterlife is hardly Christianity’s alone. Islam explicitly teaches Jannah, a paradise described as a garden, and it is the world’s second-largest religion at roughly a quarter of the current population. The Abrahamic faiths together — Christianity, Islam, and Judaism — already account for more than half of humanity alive today.^[12] So the $p = 0.33$ above isn’t “the one religion that happens to have an afterlife” — it’s simply one illustrative pick: the current population share of the single largest faith.

Not every tradition shares the picture of souls accumulating in one place, though. Hinduism and Buddhism teach reincarnation rather than a permanent residence like heaven. Instead of piling up in a single location, the soul is reborn, or its individuality dissolves entirely through moksha or nirvana. In that model, the very notion of “counting heaven’s population” doesn’t apply.^[12]

So the admission rate $p$ isn’t really asking “which religion is correct.” It’s asking which admission criterion you choose. If the righteous of every tradition find a place in their own afterlife, $p$ approaches 1; if only the adherents of a single faith are admitted — and most humans who ever lived died before that faith existed — $p$ falls much lower.

Central value used in the body text: $p = 1.0$ — the largest possible heaven.

Variable 3: Floor Area per Soul $a$

$$a = 100 \ \text{m}^2 \text{ (central estimate — studio/one-bedroom apartment equivalent)}$$

This is the single most consequential variable in the whole calculation. Neither theology nor physics pins it down. Here is the physically plausible range:

Stance: 100 m² (“comfortable without being lavish”) is the central estimate.

Variable 4 (auxiliary): New Jerusalem dimensions from Revelation

Revelation 21:16 describes the heavenly city of the New Jerusalem: “The city was laid out like a square … He measured the city with the rod and found it to be 12,000 stadia in length, and as wide and high as it is long.”^[5]

One stadion (the ancient Greek unit of length) falls between 178 and 192 m in scholarly consensus, with the Attic stadion of 185 m most widely cited.^[6]

$$L_{\text{NJ}} = 12{,}000 \times 185 \ \text{m} = 2{,}220{,}000 \ \text{m} = 2{,}220 \ \text{km}$$

A single side of 2,220 km: roughly the straight-line distance from New York City to Denver, Colorado — or London to Cairo.

$$A_{\text{NJ}} = 2{,}220^2 = 4{,}928{,}400 \approx 4.93 \times 10^6 \ \text{km}^2$$

For comparison, the contiguous United States covers about 8.0 × 10⁶ km²; the New Jerusalem footprint is roughly 60% of that. Revelation also describes the city as a cube — “as wide and high as it is long”^[5] — a dimension we explore separately in Step 5.

Variable 5 (baseline comparison): Earth’s dimensions

• Earth’s total surface area: $A_{\text{earth}} = 5.10 \times 10^8 \ \text{km}^2$^[7]
• Earth’s land area (including Antarctica): $A_{\text{land}} = 1.49 \times 10^8 \ \text{km}^2$^[7]

FORMULA

Step 1: Basic formula for heaven’s required area

Define: number of souls × area per soul = total heaven area. Converting m² to km²:

$$A_{\text{heaven}} [\text{km}^2] = N \cdot p \cdot a [\text{m}^2] \times 10^{-6}$$

• $N = 1.09 \times 10^{11}$ people
• $p$ = admission rate (by scenario)
• $a$ = area per soul (m²)

Step 2: Central-value substitution ($p = 1.0$, $a = 100 \ \text{m}^2$)

$$A_{\text{heaven}} = 1.09 \times 10^{11} \times 1.0 \times 100 \times 10^{-6}$$

$$= 1.09 \times 10^{11} \times 10^{2} \times 10^{-6}$$

$$= 1.09 \times 10^{7} \ \text{km}^2$$

As a fraction of Earth’s surface:

$$r_{\text{earth}} = \frac{1.09 \times 10^7}{5.10 \times 10^8} = 0.0214 \approx 2.1\%$$

As a fraction of Earth’s land area:

$$r_{\text{land}} = \frac{1.09 \times 10^7}{1.49 \times 10^8} = 0.073 \approx 7.3\%$$

Relative to the New Jerusalem footprint:

$$r_{\text{NJ}} = \frac{1.09 \times 10^7}{4.93 \times 10^6} = 2.21\text{×}$$

Under universal salvation with 100 m² per soul, heaven needs to be about 2.2 times the footprint of the New Jerusalem.

Step 3: Three-scenario comparison

$a = 100 \ \text{m}^2$ fixed; only the admission rate varies:

The comparison is striking. At the Christian-share estimate ($p = 0.33$), the New Jerusalem as described is already large enough — its single footprint can accommodate one-third of all humanity at 100 m² each. Revelation’s city only runs out of room if you believe everyone gets in.

Step 4: Working backward from the New Jerusalem — “tighter than you’d think”

If the New Jerusalem footprint ($4.93 \times 10^6 \ \text{km}^2 = 4.93 \times 10^{12} \ \text{m}^2$) is heaven, how much space does each soul get under universal admission ($p = 1.0$)?

$$a_{\text{NJ}} = \frac{A_{\text{NJ}}}{N} = \frac{4.93 \times 10^{12} \ \text{m}^2}{1.09 \times 10^{11}} \approx 45.2 \ \text{m}^2/\text{person}$$

45 m² — about 485 square feet. Larger than the average American studio apartment (roughly 350–400 sq ft)^[4], but not dramatically so. Call it a decent one-room with a kitchenette: not cramped, but not sprawling. Revelation’s New Jerusalem, taken at face value, is snugger than most people imagine.

Now run the 10% scenario:

$$a_{\text{NJ, 10\%}} = \frac{4.93 \times 10^{12}}{1.09 \times 10^{10}} \approx 452 \ \text{m}^2/\text{person}$$

The stricter the theology, the roomier the afterlife. How comfortable heaven is depends entirely on who you decide to leave out.

Step 5: The cube — checking Revelation’s 3D interpretation

Revelation 21:16 specifies that the city’s length, width, and height are all equal — a cube.

$$V_{\text{NJ}} = L^3 = (2{,}220 \ \text{km})^3 = 1.095 \times 10^{10} \ \text{km}^3$$

$1.1 \times 10^{10}$ km³ is about 1% of Earth’s total volume ($1.08 \times 10^{12}$ km³)^[7], and roughly half the volume of the Moon ($2.2 \times 10^{10}$ km³)^[11]. Stack floors at 3 m each inside that cube and you get roughly 740,000 floors. In three dimensions, the per-soul space problem essentially vanishes.

Step 6: Add animals — and the calculation breaks

Here is where the math flips entirely.

What if pets go to heaven too? Bar-On et al. (2018), published in PNAS, estimated the biomass distribution of all living organisms on Earth.^[8] Extrapolating from that framework, current insect populations alone are estimated at roughly $10^{19}$ individuals. Projecting over the full span of Earth’s biological history, a rough central estimate for the cumulative count of all animals ever is on the order of $10^{19}–10^{21}$:

$$N_{\text{anim}} \approx 10^{20} \text{ individuals} \quad (\text{central estimate, uncertainty }\pm 1\text{ order of magnitude})$$

Compared with the human total ($N \approx 10^{11}$), that is nine orders of magnitude larger. The moment animals enter the accounting, humanity’s contribution drops to rounding-error territory.

At $a = 100 \ \text{m}^2$, $p = 1.0$, $N_{\text{anim}} = 10^{20}$:

$$A_{\text{heaven, +animals}} \approx 10^{20} \times 100 \times 10^{-6} = 10^{16} \ \text{km}^2$$

That is roughly $2 \times 10^7$ times Earth’s surface — 20 million times over. Add even a single species of animal to the guest list, and heaven needs to expand to solar-system scales. The question of heaven’s size is not really a question about human numbers at all.

OUTPUT

At the central values ($p = 1.0$, $a = 100 \ \text{m}^2$), heaven needs roughly $1.09 \times 10^7$ km² — about 2.1% of Earth’s surface. Two or three Earths would be more than enough to house every human who has ever lived.

That is the first counterintuitive result. Three hundred thousand years of humanity, all given a studio apartment apiece, and 97.9% of an Earth-sized heaven sits empty. The intuitive sense of “all those billions of souls” turns out to be cosmically modest.

The second surprise comes from the New Jerusalem. The footprint of Revelation’s city alone is enough to give all of humanity roughly 45 m² each — about 485 square feet, comfortably larger than a typical American studio apartment. If only 10% are admitted, each soul gets 452 m²: a generous two-bedroom by any standard. Heaven’s spaciousness is a function of its admission theology, not its geometry. Who gets in matters far more than how big the place is.

The third reversal — and probably the sharpest — is animals. The moment even a single species of animal joins the guest list, the required area multiplies by tens of millions. All 109 billion humans become a rounding error. The question of heaven’s size is not, in any meaningful sense, a question about people. It is a question about where you draw the line.

No conclusion is being forced on you. The answer depends on how much space you allocate per soul, and on who you decide to let in. And if you’ve opted to include the animals — go back to Step 1 and start over.