Deadweight Loss Calculator

Estimate the welfare loss created when a price change reduces the quantity traded. This page also keeps the formula, examples, FAQs, and references close by so you can check the result with confidence.

What This Deadweight Loss Calculator Helps You Do

Deadweight loss is the area of the triangle created by the price gap and quantity gap. Review the formula and examples below if you want to see how the result is derived.

This page is meant to give you a fast answer, but it also helps you double-check the math before you make a decision. Start with the inputs that you already know, run the calculation, and then compare the output with the formula, examples, and FAQs below so you can see whether the answer fits the situation you are modeling.

If the result looks off, the usual causes are a unit mismatch, a missing decimal, the wrong scenario, or a value that needs to be entered as a rate instead of a total. The notes on this page are designed to make those checks easy without forcing you to leave the calculator and search for context elsewhere.

  • Use the calculator first for a quick estimate.
  • Use the formula to understand how the result is built.
  • Use the examples to compare common use cases.
  • Use the references when the answer depends on a standard or assumption.

Common Checks

A quick result is useful, but the best result is one that still makes sense when you look at it a second time. If you are comparing scenarios, try changing one input at a time so you can see which variable has the biggest impact on the final answer. That makes it much easier to spot whether the calculation matches your expectations.

It also helps to keep the context of the problem in mind. A calculator can tell you the math, but you still need to decide whether the input represents a total, a rate, an average, or a category-specific assumption. When in doubt, start with a simple example from the page and scale up from there.

  • Check that every unit matches the rest of the problem.
  • Keep rates, totals, and averages separate.
  • Adjust one variable at a time when testing scenarios.
  • Use the smallest realistic input first, then scale upward.

Scenario Planning

This calculator is especially useful when you want a quick answer before you commit time, money, or effort. Try one baseline input set, then change a single number and compare the result so you can see how sensitive the answer is to that variable.

That makes the page useful for more than just arithmetic. It becomes a small decision aid that helps you compare options, test assumptions, and explain the final number with confidence when you need to share it with someone else.

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Result

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Quick Answer: Deadweight loss is the area of the triangle created by the price gap and quantity gap. Review the formula and examples below if you want to see how the result is derived.

How to Calculate Deadweight Loss Calculator

  1. Enter the original and new price: Use the two prices that define the market change.
  2. Enter the original and new quantity: Use the quantity traded before and after the change.
  3. Read the loss: The calculator uses the triangle formula to estimate the deadweight loss.

Deadweight Loss Calculator Formula

Deadweight loss = 1/2 × price gap × quantity gap
Variable Meaning Unit
Price gap Difference between the original and new prices $
Quantity gap Difference between the original and new quantities units

Worked Examples

USA - Tax wedge
  • Original price: $100
  • New price: $120
  • Original quantity: 1000
  • New quantity: 850

Result: $1,500

A larger wedge and larger quantity change create more deadweight loss.

UK - Small market change
  • Original price: $50
  • New price: $56
  • Original quantity: 400
  • New quantity: 360

Result: $120

Smaller gaps create less welfare loss.

EU - High wedge
  • Original price: $200
  • New price: $240
  • Original quantity: 500
  • New quantity: 300

Result: $4,000

A wider wedge and bigger quantity drop produce a larger loss.

How to Interpret Your Results

Range Meaning Action
Small loss The change has limited effect on the market Check whether the change is worth the cost
Moderate loss Some value is lost in exchange Compare the policy or pricing change against alternatives
Large loss A lot of mutually beneficial trade is being blocked Revisit the price or tax design

Frequently Asked Questions

Taxes, subsidies, quotas, and other distortions can reduce the number of mutually beneficial trades.

It measures lost economic surplus, so a larger value means more efficiency loss.

Yes. Enter the original and new price and quantity after the tax change.
Planning note: This calculator uses a simplified triangle approximation and does not model broader market feedback.

References

Last reviewed: March 2026