A hotel considering a tenth housekeeper doesn't evaluate the worker in isolation — it evaluates whether the additional rooms cleaned per day translate into revenue that covers the wage. If the tenth housekeeper cleans 12 additional rooms per day, and each room-cleaning service generates $15 in revenue, the marginal revenue product is $180. If the daily wage is $150, hiring is profitable. If the wage is $200, don't hire. That single comparison — MRP versus wage — is the entire logic of the labor demand decision.
The formula
Marginal Revenue Product of Labor (MRP_L) = Marginal Product of Labor (MPL) × Marginal Revenue (MR)
For a competitive firm where MR = Price: MRP_L = MPL × P
For a firm with market power where MR < Price: MRP_L = MPL × MR < MPL × P
Firms with market power in their product market will hire fewer workers than competitive firms because MR < P — each additional unit of output earns less than its market price.
Reading the result
The profit-maximizing hiring condition: hire workers until MRP_L = Wage (W)
- If MRP_L > W: the additional worker generates more revenue than they cost → hire
- If MRP_L < W: the additional worker costs more than they generate → don't hire
- If MRP_L = W: the marginal worker just covers their wage → optimal staffing level
Because MPL decreases as more labor is added (diminishing returns), MRP_L also decreases as hiring increases. This means the MRP_L curve slopes downward — it is the firm's labor demand curve: at each wage, the firm hires up to the quantity where MRP_L equals that wage.
Worked example
A competitive coffee roaster sells coffee at $20 per kilogram. Hiring data:
| Workers | Additional kg/day (MPL) | MRP_L (= MPL × $20) |
|---|---|---|
| 5th | 15 | $300 |
| 6th | 12 | $240 |
| 7th | 9 | $180 |
| 8th | 7 | $140 |
At a daily wage of $200: hire through the 6th worker (MRP = $240 > $200). Stop before the 7th (MRP = $180 < $200). Optimal: 6 workers.
The Bureau of Labor Statistics Occupational Employment and Wage Statistics tracks wages across thousands of occupations — the wage side of the MRP equation. Wage differentials between occupations reflect differences in MRP: surgeons earn more than nurse aides because each additional surgeon hour generates substantially more MRP in the healthcare market.
Where it's used
MRP is the foundation of all factor demand theory. It explains why higher-productivity workers earn higher wages (higher MPL → higher MRP → higher wage in competitive equilibrium), why skilled trades command premiums over unskilled labor, and how automation affects labor demand (machines raise or lower MRP depending on whether they substitute for or complement worker skills). The BLS Productivity data tracks the aggregate MPL trend — when productivity rises, MRP rises, and competitive wages should follow.
