--- title: Carbon Dioxide Test type: biomarker url: "https://www.test-well.com/biomarkers/carbon-dioxide" also_known_as: - co2 - carbon dioxide - bicarbonate - hco3 - carbon dioxide, total category: Metabolic Health units: - mmol/L - mEq/L order_price_usd: 20.99 order_item: Basic Metabolic Panel order_url: "https://www.test-well.com/tests/basic-metabolic-panel" reviewed_at: 2026-09-05 --- # Carbon Dioxide > Carbon Dioxide is measured with a standard blood draw after an 8–12 hour fast. A typical reference range is 22.0 – 29.0 mmol/L. At TestWell it's $20.99 all-in as Basic Metabolic Panel, results in 1–3 business days, drawn at Quest or Labcorp. An out-of-range result is a prompt to look closer, not a diagnosis. Also known as: co2, carbon dioxide, bicarbonate, hco3, carbon dioxide, total. ## Key facts | Fact | Value | | --- | --- | | Units | mmol/L / mEq/L | | Sample | Blood draw | | Fasting | 8–12 hours | | Results | 1–3 business days | | Price | $20.99 | | Labs | Quest or Labcorp · BioReference in NY/NJ | ## What does Carbon Dioxide measure? Mostly bicarbonate. Reflects your body's acid-base balance. ## What is the normal range for Carbon Dioxide? | Population | Reference range | | --- | --- | | age 18+ | 22.0 – 29.0 mmol/L | Reference intervals differ slightly between labs; the range printed on your report is the one to interpret against. Ranges are usually set so 95% of healthy people fall inside them. ## How do you get tested for Carbon Dioxide? | Order | Type | Price | Includes | | --- | --- | --- | --- | | [Basic Metabolic Panel](https://www.test-well.com/tests/basic-metabolic-panel) | Single test | $20.99 | This marker | ## Quest vs Labcorp vs BioReference | Lab | Available | Price | Notes | | --- | --- | --- | --- | | Quest Diagnostics | Yes | $20.99 | Choose Quest at checkout; walk-in patient service centers in every state TestWell serves outside NY and NJ. | | Labcorp | Yes | $21.99 | Choose Labcorp at checkout; walk-in patient service centers in every state TestWell serves outside NY and NJ. | | BioReference (NY & NJ) | Yes | $22.99 | New York and New Jersey orders route here automatically — state rules keep Quest and Labcorp from accepting self-ordered draws. | - [What a high Carbon Dioxide means (causes, symptoms, next steps)](https://www.test-well.com/biomarkers/carbon-dioxide/high) - [What a low Carbon Dioxide means (causes, symptoms, next steps)](https://www.test-well.com/biomarkers/carbon-dioxide/low) ## Common questions about Carbon Dioxide ### Do I need a doctor's order to test my carbon dioxide? No. TestWell's licensed physician network reviews and approves your order — usually within minutes. You can place an order online without an in-person visit or a referral from your own doctor. ### How long does it take to get Carbon Dioxide results? Most Carbon Dioxide results are available in 1–3 business days after your specimen arrives at the lab. You'll get an email the moment your results are ready, with everything viewable in your TestWell portal. ### How much does a Carbon Dioxide test cost? Our Basic Metabolic Panel starts at $20.99. That's the all-in price — no copays, no insurance hoops, no surprise bills. HSA and FSA cards are accepted. ### Do I need to fast before my Carbon Dioxide test? Yes — for the most accurate result, fast for 8–12 hours before your blood draw. Water is fine; coffee, food, and supplements are not. Your prep instructions will be included with your order. ### Which lab will process my Carbon Dioxide test? Your test will be processed by Quest Diagnostics, Labcorp, or BioReference depending on which is closest to you and which lab carries the test. All three are CLIA-certified and trusted by hospitals nationwide. You'll choose your lab during checkout from 4,000+ locations. ## Sources - [Mayo Clinic Labs](https://www.mayocliniclabs.com/test-catalog/overview/8434) - [MedlinePlus (NIH) — Carbon Dioxide (CO2) in Blood](https://medlineplus.gov/lab-tests/carbon-dioxide-co2-in-blood/) ## Related biomarkers - [Glucose](https://www.test-well.com/biomarkers/glucose) - [Creatinine](https://www.test-well.com/biomarkers/creatinine) - [eGFR](https://www.test-well.com/biomarkers/egfr) - [BUN](https://www.test-well.com/biomarkers/bun) - [ALT](https://www.test-well.com/biomarkers/alt) - [AST](https://www.test-well.com/biomarkers/ast) - [Reference range lookup tool](https://www.test-well.com/tools/reference-range-lookup) - [Lab unit converter](https://www.test-well.com/tools/lab-unit-converter) - [All biomarkers](https://www.test-well.com/biomarkers) --- Medically reviewed by Youmna DiStefano, MD (Medical Reviewer, TestWell); last reviewed 2026-09-05. Review policy: https://www.test-well.com/reviewers/youmna-distefano-md Canonical page: https://www.test-well.com/biomarkers/carbon-dioxide Machine-readable catalog: https://www.test-well.com/api/catalog.json · MCP server: https://www.test-well.com/mcp · Overview for agents: https://www.test-well.com/llms.txt Prices are cash-pay, in USD, and include physician authorization; every order adds one flat $6 lab processing fee. Educational content is not a diagnosis — discuss results with a clinician.