Marx's economics, in three stages: the basic idea, seeing it worked through, and measuring it in the real world economy.
Karl Marx argued that profit under capitalism comes from a specific source: workers produce more value in a working day than they're paid in wages, and that gap — surplus value — is where profit comes from. He also argued that competition between capitalists drives them to keep replacing workers with machinery, which raises what he called the organic composition of capital (more machinery and materials relative to the workers actually producing value) — and that this tends, over time, to push the rate of profit down, even as the total mass of profit can keep growing.
That's a testable claim about how real economies behave, not just a theory. The tools on this site go from the basic arithmetic of exploitation, through interactive explanations of how the pieces fit together, to actually computing these measures from real national-accounts data — Penn World Table, US BEA, OECD, WIOD — and checking them against what economist Michael Roberts has published on his own long-running analysis of world profitability.
Type in your own numbers, see the concept directly
Small, single-purpose calculators. Each one takes a couple of numbers you choose — hours worked, a wage, how much capital is reinvested — and shows you the Marxist arithmetic behind it: necessary vs. surplus labour time, the rate of exploitation, how profit rates equalise across industries, how capital accumulates over repeated cycles.
All basic calculators →
The full set: exploitation rate, working-day split, capital accumulation, profit-rate equalisation, turnover of capital, and more.
Exploitation calculator
Set hours, wage and value produced per hour — see necessary vs. surplus labour time and the resulting rate of exploitation.
Working day & profit rate
The fullest single calculator: working day, wages, constant capital, and the resulting Marxian rate of profit, all in one page.
Profit-rate equalisation
Marx's classic multi-industry example: why competition pulls different industries' profit rates toward one economy-wide average.
The circuit of capital
Money → commodities (labour-power + means of production) → production → more commodities → more money. Adjust the split and watch the circuit.
Turnover of fixed capital
Why capital that turns over faster generates more annual surplus value from the same stock — and how that changes the annual rate of profit.
Interactive explainers, real and illustrative data side by side
These go a level up from single numbers: historical trends, cross-country comparisons, and — where the underlying data actually supports it — a toggle between a real, sourced result and a "play with hypothetical numbers" mode for exploring the concept freely.
Marx's Economic Theories
Labour theory of value, capital accumulation, and the tendency for the rate of profit to fall — charted from Penn World Table, BEA, OECD STAN, WID.world and WIOD data, with a real/hypothetical toggle on the charts where it matters.
In progressMarxist Economics Made Clear
Surplus value and exploitation, worked through with adjustable sliders and real-life framing. Six further modules (use-value vs. exchange-value, living vs. dead labour, and more) are planned but not yet built.
Marx's laws, measured — and checked against what's actually been published
The most demanding tier: every number here is computed from real national-accounts data with full provenance (source, formula, vintage), and checked wherever possible against Michael Roberts's own published figures on world and national rates of profit.
These are static snapshots, not live calculators. The full, fully interactive versions — pick any country set, any date range, any aggregation method — run from the marxist-ai project's own live backend, which this deployment doesn't have. What's shown here is one real, correctly-sourced result per tool, computed the same way the live version would.
World rate of profit
r = s / (C+v), G20 aggregate, 1950–2023, from Penn World Table 11.0 — the core measure Roberts's own world-profitability analysis is built on.
Real dataWorld class shares
Labour's and capital's share of value added, by country and in aggregate — the wages-vs-profit split behind the rate of profit.
Real dataUS rate of profit
Nonfinancial corporations, 1929–2024, from BEA NIPA and Fixed Assets Accounts — the crisis (1965–82), neoliberal recovery (1982–97), and Long Depression periods Roberts periodises.
Real dataOECD rate of profit — new source
The same calculation from a second, independently-updated data source (OECD STAN) instead of PWT — an independent check, not a duplicate.
Real dataUS class shares
The US-specific labour/profit split over time, at NFC-sector detail.
Real dataProfit vs. investment
Does a falling profit rate actually lead a fall in investment, and by how long? Tested directly against US data.
Real dataProfit cycles
Dating peaks in the mass of profit against peaks in the rate of profit — the mass/rate distinction that explains why "record profits" and a falling rate of profit aren't a contradiction.