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Capex and depreciation: how to read the capital cycle

September 12, 2026 · 8 min readfundamentalscapital-cycleeducation

Capex is cash spent on long-lived assets. Depreciation is an accounting charge that spreads the cost of those assets through the years they are expected to serve the business. They describe the same economic machinery from different points in time: one records the cash leaving today; the other records part of an earlier purchase arriving on today's income statement.

Compare the two and you get a useful read on the capital cycle. Capex above depreciation often means a business is building, replacing assets at higher prices, or both. Capex below depreciation can mean the buildout has finished, or that management is taking more out of the asset base than it is putting back. The comparison can't sort maintenance spending from growth spending on its own. It gives you a question to take to the filing, then a measurable footprint you can test.

This is the next link in the chain after operating cash flow versus net income. That article explained why depreciation makes cash flow run ahead of earnings at equipment-heavy businesses. This one follows the cash back to the moment the equipment was bought.

Capex is paid now; depreciation arrives later

Capital expenditures, usually shortened to capex, are cash payments for assets intended to work for more than one reporting period: a factory, rail track, a cable network, a fleet, a server farm. On a cash flow statement, the line is commonly some version of purchases of property and equipment. It belongs in investing activities because the company is acquiring a long-lived resource.

Depreciation is the allocation of that asset's cost across its useful life. Buy a machine, then use it over several years. Accounting doesn't charge the whole purchase against this quarter's sales. It records an expense each period as the machine is used. Amortization does the same job for an intangible asset, such as a purchased customer relationship or a software license. Filers usually combine the two as D&A.

The timing mismatch is deliberate. If capex and depreciation were always equal in each period, there'd be little to discuss. They rarely are. A company can spend heavily for years before the first customers arrive, then continue recording depreciation long after the construction crew has left. A mature company can replace worn-out equipment at roughly the same pace as its depreciation charge. A business can also delay investment for a while and make free cash flow look much better than its asset base deserves.

That is why depreciation is added back in the operating section of the cash flow statement. It reduced net income, though the cash was paid in an earlier period. Capex then appears in investing activities, where the current-period cash payment is visible. For the map of how those statements connect, start with the three financial statements.

The capex-to-D&A gap points to the capital cycle

The first ratio is short:

capex-to-D&A = capital expenditures / depreciation and amortization

A ratio above one says current cash investment exceeds the current accounting charge. It doesn't prove that a company is growing productively. New capacity might be needed for a contract, a regulatory upgrade, inflation in construction costs, or an acquisition integration. The asset could turn out to be a very good investment or a very expensive mistake.

A ratio below one also needs context. A software business may need little physical capital, so low capex can be structural. A railroad or cable operator needs constant replacement investment, so the same ratio can signal a different stage of the cycle. One year's shortfall might reflect a completed project. Several years of underspending could leave the business with an aging network and a flattering free-cash-flow number. You can't tell which story applies from the ratio alone.

The central limitation is that US financial statements do not provide a standard audited line called maintenance capex. Management may describe a project as expansion, upgrade, replacement, capacity, or something else in its release and capital plan. Those labels help a reader form a judgment. They do not turn the capex line into a clean split between spending required to keep the business running and spending intended to enlarge it.

Use the ratio as an invitation to read. Pull the capital-investment discussion and the property-and-equipment note in a few filings. Ask what was built, why it was built, and what has to be spent again. Then write the part you can measure down as a rule.

Charter shows why the two lines need to be read together

Charter Communications' full-year 2024 release gives the arithmetic a real physical setting. The company reported $11.269 billion of capital expenditures and $8.673 billion of depreciation and amortization, a difference of $2.596 billion. It also reported $4.216 billion of line extensions within capital expenditures. Charter's full-year release supplies each figure.

The gap tells you that Charter spent more on long-lived assets in that year than the D&A charge running through the income statement. It doesn't tell you how much was maintenance. Line extensions are useful evidence that part of the spending was aimed at reaching more locations, yet the release's capex categories don't give an audited maintenance-versus-growth split. The remaining spending includes customer-premise equipment, scalable infrastructure, upgrade and rebuild work, and support capital. A single number can't settle which dollars will earn a return.

It does settle something smaller and useful. An analyst who reads EBITDA alone sees the D&A charge added back. An analyst who reads capex alongside it sees the cash claim that is still being made on the business. That's why EBITDA needs a capital-charge companion, especially for networks, utilities, transport, and manufacturers.

The same lesson cuts the other way. High capex today can create useful capacity for a long time. Low capex today can be a sign of discipline. The filing supplies the story. The ratio makes the stories comparable once you have defined which version you mean to test.

Put the comparison into a thesis

Quantery's Greenblatt Magic Formula template already makes one deliberately rough version of this comparison. It starts with trailing EBITDA, then adds trailing capex because capex is stored as a negative cash outflow. That subtracts capex from EBITDA as a stand-in for depreciation, producing an EBIT proxy. The template says exactly where that approximation can break: maintenance capex and depreciation are only estimates of each other.

The shape below is illustrative. The bundled templates and the DSL reference are the source for exact fields. It keeps the two components visible instead of hiding their difference inside a single earnings measure.

# "Capital cycle read" - illustrative
params:
  reinvestment_high: 1.25     # capex meaningfully above D&A
  reinvestment_steady: 0.80   # lower band for a mature asset base

features:
  capex_ttm: ttm(capex)
  da_ttm:    ttm(depreciation_amortization)
  capex_to_da: if(da_ttm > 0, -capex_ttm / da_ttm, null)
  fcf_ttm:   ttm(free_cash_flow)
  ocf_ttm:   ttm(operating_cash_flow)
  fcf_margin: if(ocf_ttm > 0, fcf_ttm / ocf_ttm, null)

criteria:
  reinvestment_pace:
    rules:
      - { when: "is_null(capex_to_da)", score: 0, flag: no_capital_cycle_read }
      - { when: "capex_to_da >= $reinvestment_high", score: 2 }
      - { when: "capex_to_da >= $reinvestment_steady", score: 1 }
      - { else: 0 }
  cash_after_investment:
    rules:
      - { when: "is_null(fcf_margin)", score: 0, flag: no_cash_read }
      - { when: "fcf_margin > 0", score: 2 }
      - { else: 0 }

gate:
  mode: score
  min_score: 2

The minus sign is doing real work. The cash-flow field records capex as an outflow, so its trailing sum is negative. Negating it produces the familiar positive-spend-over-positive-D&A form. The da_ttm > 0 guard matters too. A company with no recorded D&A should yield a missing result instead of an infinite score.

The named bands are proposed thresholds. Start round. Then test a range around each one and record what changed. A thesis that requires a narrow setting to work has told you something important about itself.

There are two different studies hiding in this code. One asks whether companies increasing their asset base while preserving cash flow have a pattern worth investigating. The other asks whether the market prices businesses spending ahead of their depreciation charge differently from mature asset owners. Keep them as separate theses. A composite score that rewards both rapid investment and the cash conservation that rapid investment reduces will blur the result.

Test the footprint across time, then read the exceptions

Run the version you chose through a point-in-time backtest. The result is hypothetical and excludes costs. It can show how companies matching the filed footprint performed after each qualification, using the information available at the time. It can't tell you whether the next data-center, pipeline, or network project will earn its projected return. What a backtest can establish is narrower and more useful than that.

Break the results out by industry before you infer much. Capex is the business model for some companies and a rare event for others. A universal threshold can become an industry bet without announcing itself. Try a version that excludes financial businesses, where the ratio has little meaning. Then run a second version that compares each sector separately. If the apparent result disappears, the original thesis was probably reading sector mix.

Then inspect the names at both ends of the ratio. Open the capital-plan language and the property note. Did a high ratio accompany a new facility, a repair program, a network extension, or a catch-up spend after years of deferral? Did a low ratio follow the completion of a project, or did it coincide with assets being run down? That work doesn't turn into an automatic rule. It tells you whether the next version of your rule deserves to exist.

Capex records the cash commitment. Depreciation records how that commitment is being charged through earnings. Read both, write down the claim that joins them, and make the rules yours.

Want to try this on your own rules? Quantery is free for 14 days: the full app, no card required.

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