# MPC Calculator – Marginal Propensity to Consume

URL: https://speedycalculator.com/calculators/finance/mpc/
Last updated: 2026-10-25

> The MPC calculator works out the marginal propensity to consume – the share of each extra dollar of income that is spent – and the matching MPS and Keynesian spending multiplier.

## Inputs

- Change in consumption
- Change in disposable income

## Results

- Marginal propensity to consume
- Marginal propensity to save
- Spending multiplier

## Formula

```
MPC = change in consumption ÷ change in income
MPS = 1 − MPC
Spending multiplier = 1 ÷ (1 − MPC)
```

## Explanation

Lower-income households usually have a higher MPC because they spend more of any extra income. A higher MPC means fiscal stimulus has a larger multiplier effect.

### How to use the MPC Calculator – Marginal Propensity to Consume

- **Change in consumption**
- **Change in disposable income**

Results update as you type, and every field accepts the units shown in its menu.

### How it works

Enter the change in consumption and the change in disposable income.

### Tips

- Use real (inflation-adjusted) figures to compare across years.
- Check whether data are seasonally adjusted.
- Use the same currency and base year throughout.
- Economic models simplify reality – treat results as illustrations, not forecasts.

### Common mistakes to avoid

- Mixing nominal and real values.
- Comparing percentage changes with percentage-point changes.
- Treating correlations as causes.

### Inputs explained

FieldWhat to enterChange in consumptionAmount in your currencyChange in disposable incomeAmount in your currency

### What each result means

- **Marginal propensity to consume** = [Change in consumption]÷[Change in disposable income]
- **Marginal propensity to save** = 1 - [Change in consumption]÷[Change in disposable income]
- **Spending multiplier** = 1÷(1 - [Marginal propensity to consume])

### Example values

How the main result changes when **Change in consumption** changes and everything else stays at the example values above:

Change in consumptionMarginal propensity to consume4000.46000.68000.81,00011,2001.21,6001.6

## Worked example

Inputs — Change in consumption: $800; Change in disposable income: $1,000.

Results — **Marginal propensity to consume = 0.8**; Marginal propensity to save = 0.2; Spending multiplier = 5.

## FAQ

**What is MPC?**
The fraction of additional income spent on consumption.

**What is the relationship between MPC and MPS?**
They add up to 1.

**How does MPC affect the multiplier?**
Multiplier = 1 ÷ (1 − MPC).

**What formula does the MPC Calculator – Marginal Propensity to Consume use?**
MPC = change in consumption ÷ change in income.