Build the repair bill the way the shop builds it
A repair bill is parts plus labour plus the small print: a diagnostic fee (often credited back when you approve the work), a shop supplies charge, disposal, tax on a basis that depends on your state, and sometimes a minimum. This page itemizes all of it at your figures: name each part and its price as quoted, enter the labour hours and the shop’s hourly rate, and set the fees and the tax basis to match the estimate in front of you. The result shows every line, the subtotal, any minimum charge applied openly, contingency, tax on the basis you chose, the total, a low to high range, and the all-in cost per labour hour, with a downloadable estimate for comparing shops.
Parts
Enter part prices as quoted to you. A shop’s part price usually carries a markup over its trade cost, which is normal trade practice and separate from the labour charge; what matters for comparison is the price on your estimate, so enter that.
Labour and diagnosis
Shop charges
Minimum, contingency, tax and range
Disclaimer: This calculator gives estimates for general information only. It is not financial, medical or other professional advice. It does not diagnose any vehicle fault; the binding figures for a repair are those on the written estimate you authorise with the shop.
What this calculator does
It rebuilds a vehicle repair estimate from its components so two shops’ paperwork can be compared on identical lines. Parts are entered individually at quoted prices; labour is hours times the shop rate; the diagnostic fee is handled the way your shop described it, charged or credited; shop supplies are taken as the percentage of parts and labour that appears on real estimates; disposal and other charges sit flat; and tax is applied once, on the basis (parts only, parts and labour, or the whole amount) that matches your state and your estimate. The strict estimator discipline applies on top: lines rounded to cents, any minimum charge applied openly, a contingency for what the teardown finds, a range around the total, and the all-in cost per labour hour, which exposes at a glance how much of a bill is time and how much is everything else.
How to use it
- Transcribe the estimate, do not summarise it. The value of the page is line-by-line fidelity: each part at its quoted price, the hours as printed, the fees as named. Two estimates for the same job usually differ in the small lines, and a summary total hides exactly where.
- Ask which hours you are buying. Most shops bill labour from a standard time guide for the operation, not the minutes the technician spends. Guide time is a legitimate system (it makes quotes comparable), but it means a fast technician does not lower your bill, and it makes the hours the thing to question when a quote looks high: the same job at 2.4 hours and at 3.6 hours differs by half the labour charge before any rate is discussed.
- The diagnostic fee question is “credited or not”. Paying for diagnosis is fair; paying for it twice is not. If a shop charges to diagnose and then charges the full repair that the diagnosis defined, ask whether the fee is credited. The treatment selector on this page exists so both versions of the same quote can be priced honestly.
- Shop supplies are real but should be visible. A percentage for consumables is common practice; what is not reasonable is discovering it at the till. Enter it where an estimate shows it, and treat its absence from a written quote as a question to ask before authorising, not after.
- Set the tax basis to your state before comparing totals. Two identical estimates can carry different totals purely because one state taxes labour and another does not. Comparing pre-tax subtotals across state lines, and totals within one, avoids chasing a difference that belongs to the tax code rather than the shop.
How it is calculated
- Parts subtotal = the sum of the part prices entered. Labour = labour hours x rate per hour.
- Diagnostic fee enters in full when set to charged, and at zero when set to credited against the repair, with the results naming the treatment either way.
- Shop supplies = your percentage x (parts subtotal + labour). Subtotal = parts + labour + diagnostic (as treated) + shop supplies + disposal + other fixed charges, each money line rounded to cents first.
- Minimum charge: if a minimum is entered and exceeds the subtotal, the minimum becomes the base and the results state that the minimum charge applied. Contingency = your percentage once on the base. Tax = your rate applied to the basis selected: parts only, parts and labour, or the base plus contingency. Total = base + contingency + tax. Range = total less and plus your percentage. Per labour hour = total / labour hours.
Worked examples
An alternator job, on paper. Illustrative figures from a typical written estimate: alternator $329.99 and a serpentine belt $42.50 give a parts subtotal of $372.49. Labour 2.4 hours at $95 is $228.00. The $120 diagnostic fee is credited against the repair, so it enters at $0.00 and the results say so. Shop supplies at 5% of parts and labour are $30.02; disposal $15.00. Subtotal $645.51. Contingency at 5% adds $32.28, and tax at 8% on parts only adds $29.80, for a total of $707.59, or $294.83 per labour hour all-in, ranging from $636.83 to $778.35 at plus or minus 10%.
The same job, fee not credited. Flip the diagnostic treatment to charged and the subtotal rises by exactly the $120 fee, to $765.51 before contingency and tax. Nothing else moves. That one policy difference is worth more than most haggling over the hourly rate achieves, which is why it gets its own selector instead of a footnote.
A diagnostic-only visit meets the floor. A $120 diagnostic fee with no repair authorised, against a shop minimum of $150: the estimate builds on the minimum and totals $150.00, stating that the minimum charge applied. Small visits are priced by minimums and flat fees, and this page shows that instead of pretending the fee was the whole story.
Reading your results
Start with the per-labour-hour figure: it compresses the whole bill (parts markup, fees, tax and all) into the hours bought, and it is the fastest sanity check when one quote is far from another. Then look at the parts-to-labour balance: parts-heavy bills turn on part prices and brand choice (manufacturer, quality aftermarket, remanufactured), while labour-heavy bills turn on hours and rate, and each has a different conversation attached. Finally, read the contingency line as what it is, a stated allowance for the seized bolt, the brittle connector and the second fault hiding behind the first, and agree with the shop what happens when it is not needed.
Limitations
- This page prices an estimate; it does not diagnose. It cannot tell you what is wrong with a vehicle, whether a quoted repair is the right one, or whether a part should be new, remanufactured or used. Those are questions for the inspection you are paying the diagnostic fee for.
- Guide time is not your vehicle’s clock. Labour hours here are the hours entered from an estimate. Whether those hours match the published guide for the operation is a question the shop can answer from the guide itself; the page cannot audit a guide it has never seen.
- Teardown changes bills. Many accurate totals only exist once covers are off. Contingency is an allowance, not a cap, and reputable shops re-authorise before spending beyond the estimate you approved.
- Tax rules vary by state and by repair type. The basis selector covers the common patterns; it is not tax advice, and warranty, insurance and fleet work can each follow different rules again.
Frequently asked questions
What should a repair estimate include?
Itemized parts with prices, labour hours and the hourly rate, and every fee named in the open: diagnostic, shop supplies, disposal, tax and its basis. An estimate that shows only a total cannot be compared, questioned or held to account, and rebuilding it line by line, as this page does, is how a second quote becomes a real check on the first rather than a second guess.
Why is labour charged by guide hours instead of actual time?
Standard time guides publish the hours an operation should take a competent technician with proper equipment. Billing by the guide makes quotes consistent between shops and insulates you from a slow day, at the cost of also not rewarding a fast one. It is the dominant system in the trade; the practical response is to compare the hours for the same operation between estimates, which this page makes visible as its own line.
Is a diagnostic fee normal, and should it be credited?
Charging for diagnosis is normal: finding the fault is skilled work, and the fee buys the inspection whether or not you proceed. Crediting it against the resulting repair is common but not universal, and it is a policy worth one question before the work starts. This page prices both treatments explicitly so the difference appears in dollars rather than in surprise.
What is a shop supplies charge?
A percentage of parts and labour (or a flat fee at some shops) covering consumables the job uses up: cleaning solvents, rags, lubricants, small fasteners and the like. It is a recognised line on many estimates and a contested one when it appears unannounced. Enter it here only where an estimate actually shows it, at the percentage shown.
Related calculators
Method: itemized parts at entered prices, labour at entered hours and rate, fees as defined on this page, tax applied once on the selected basis, minimum charge and contingency as stated. Last reviewed: 13 October 2026.