Discount Impact Calculator
A discount comes out of profit, not revenue — which is why 10% off can erase a quarter of what a job earns. Enter your price, the job's cost and the discount to see the profit lost and the extra volume needed to replace it.
Method and content reviewed September 23, 2026 · formulas checked against a test suite · runs entirely in your browser
Profit before ÷ Profit after = jobs needed to stand still$450.00 ÷ $330.00 = 1.36 jobsTo earn what one full-price job earned, you'd need 1.36 jobs at the discounted price — 36.4% more work, more trips and more risk for the same money.
This is the arithmetic that makes "give them 10% and make it up on volume" so expensive: the discount comes out of the smallest number on the job.
What each discount does to this job
The same job at your price and cost, discounted by common amounts. Volume needed is how many discounted jobs it takes to replace the profit of one job at full price.
| Discount | Price | Profit | Margin | Profit erased | Volume needed |
|---|---|---|---|---|---|
| 5% | $1,140.00 | $390.00 | 34.2% | 13.3% | 1.15× |
| 10% | $1,080.00 | $330.00 | 30.6% | 26.7% | 1.36× |
| 15% | $1,020.00 | $270.00 | 26.5% | 40.0% | 1.67× |
| 20% | $960.00 | $210.00 | 21.9% | 53.3% | 2.14× |
| 25% | $900.00 | $150.00 | 16.7% | 66.7% | 3× |
| 30% | $840.00 | $90.00 | 10.7% | 80.0% | 5× |
"Never" means the discounted price no longer covers the job's cost — no amount of volume recovers it.
Plumbing: where the number comes from
A repeat customer asks a plumber for 10% off a $1,200 job that costs $750 in labor, parts and disposal. (Illustrative example — use your own numbers.)
| Input | Value |
|---|---|
| Normal price | $1,200 |
| Job cost | $750 (labor, parts, disposal) |
| Discount requested | 10% |
Result: 10% off erases 26.7% of the profit — you'd need 36% more jobs to earn the same money
The discount is 10% of the price but 26.7% of the profit, and it pulls the margin from 37.5% to 30.6% — below what the job was priced to carry. If the customer needs a lower number, removing a line of scope keeps the margin on the work that remains; a flat discount on the same scope doesn't.
Load this example into the calculatorThe calculation
| Profit before | $1,200 − $750 = $450.00 |
| Discounted price | $1,200 × 0.90 = $1,080.00 |
| Profit after | $1,080 − $750 = $330.00 |
| Profit erased | ($450 − $330) ÷ $450 = 26.7% |
| Margin after | $330 ÷ $1,080 = 30.6% |
| Extra jobs to match one old job | $450 ÷ $330 = 1.36 jobs (36.4% more) |
How this calculator works
Every result comes from the formulas below — the math shown is the math used. Change any input and results update instantly in your browser; nothing is sent to a server.
- Discounted price:
Discounted Price = Price × (1 − Discount ÷ 100) - Profit at each price:
Profit = Price − Job CostYour costs don't shrink when the price does — that's the entire problem with discounting. - Share of profit erased:
Erased % = (Profit before − Profit after) ÷ Profit before × 100A 10% discount on a 37.5%-margin job erases 26.7% of the profit, not 10%. - Extra volume to stand still:
Volume Multiplier = Profit before ÷ Profit afterHow many discounted jobs it takes to earn what one job used to earn.
What the result means
The profit after the discount is real money you keep once the job's costs are paid. The erased share and the volume multiplier are the same fact stated twice: a discount is taken out of the smallest number in the job, so it costs far more profit percentage than price percentage.
When to use it
Use it before agreeing to any discount, to see what it costs in profit and how much extra work would be needed to replace it. It's also the honest answer to 'can you do better on price?' when the answer is scope, not price.
Want the concept behind the math in depth? Read What a Discount Really Costs (And What to Offer Instead) or Markup vs. Margin: The Pricing Difference That Costs Contractors Money or When to Raise Your Prices — and How Much You Can Afford to Lose.
Common mistakes
- Comparing a discount to a markup as if they were symmetric — they aren't; costs don't discount themselves.
- Discounting the same scope instead of removing a line of work, which lowers the price and the margin at the same time.
- Treating 'we'll make it up on volume' as arithmetic: check the volume multiplier before believing it.
Frequently asked questions
Why does a 10% discount cost more than 10% of my profit?
Because the discount is measured against the price while profit is a fraction of the price. A $1,200 job that costs $750 earns $450, a 37.5% margin. Ten percent off is $120 — measured against the price that's 10%, but measured against the profit it's 26.7%. The smaller your margin, the more brutal the arithmetic: on a 15% margin, a 10% discount wipes out two-thirds of the profit.
How much extra work does a discount require to break even?
Divide the profit before the discount by the profit after. On the example above, $450 ÷ $330 = 1.36, so you'd need 36% more jobs to earn the same money. This is why discounting for volume only makes sense when you have idle capacity and the extra work genuinely costs nothing more than variable cost — otherwise you're buying revenue with profit.
Should I ever discount?
Yes, when it buys something specific: work that fills capacity you'd otherwise waste, a trade for faster payment or flexible scheduling, bundled repeat work, or a customer acquisition you're deliberately paying for. What doesn't work is discounting as a reflex to a lower competing bid — that sets a price expectation you'll have to live with on every future job.
Is it better to discount or to reduce the scope?
Reducing scope, almost always. A discount on the same scope lowers both the price and the margin percentage, so the job carries proportionally less overhead than your pricing assumed. Removing a line — the optional fixture, the second coat, the trim detail — lowers the price while keeping the same margin on the work that remains. Same customer outcome, protected economics.
What is the lowest price I can accept on a job?
The floor is the job's variable cost plus the overhead it must carry — at or below that, the work is subsidising the customer. Use the Margin Calculator to check the margin any final price actually carries, and your Overhead Calculator to know what share of revenue the job is expected to contribute. Below the floor, it's cheaper to leave the job unbooked.
Before you agree to a lower number, check the margin that price actually leaves.
Check the margin on this price →Related tools and guides
Discount Impact Calculator is part of RateCraft, a set of free pricing and estimating tools for contractors and service businesses. Results are calculated entirely in your browser and are estimates for planning purposes — see our disclaimer and methodology.