--- title: RDW Test type: biomarker url: "https://www.test-well.com/biomarkers/rdw" also_known_as: - rdw - red cell distribution width category: Blood Health units: - "%" order_price_usd: 21.99 order_item: CBC with Differential order_url: "https://www.test-well.com/tests/cbc-with-differential" reviewed_at: 2026-09-05 --- # RDW > RDW is measured with a standard blood draw; no fasting is needed. A typical reference range is 11.5 – 14.5 %. At TestWell it's $21.99 all-in as CBC with Differential, 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: rdw, red cell distribution width. ## Key facts | Fact | Value | | --- | --- | | Units | % | | Sample | Blood draw | | Fasting | Not required | | Results | 1–3 business days | | Price | $21.99 | | Labs | Quest or Labcorp · BioReference in NY/NJ | ## What does RDW measure? How much your red blood cells vary in size. Elevations often appear early in nutritional deficiencies. ## What is the normal range for RDW? | Population | Reference range | | --- | --- | | age 18+ | 11.5 – 14.5 % | 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. ## What does a high RDW mean? Often reflects iron, B12, or folate deficiency, or recent blood loss. ## How do you get tested for RDW? | Order | Type | Price | Includes | | --- | --- | --- | --- | | [CBC with Differential](https://www.test-well.com/tests/cbc-with-differential) | Single test | $21.99 | This marker | | [General Wellness Panel](https://www.test-well.com/tests/general-wellness-panel) | Panel | $49.99 | 4 tests | | [Baseline Anemia Panel](https://www.test-well.com/tests/anemia-panel) | Panel | $74.99 | 5 tests | | [Fatty Liver Panel](https://www.test-well.com/tests/fatty-liver-panel) | Panel | $92.99 | 6 tests | | [Post-COVID Recovery Panel](https://www.test-well.com/tests/post-covid-panel) | Panel | $99.99 | 7 tests | ## Quest vs Labcorp vs BioReference | Lab | Available | Price | Notes | | --- | --- | --- | --- | | Quest Diagnostics | Yes | $21.99 | 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 | $18.99 | New York and New Jersey orders route here automatically — state rules keep Quest and Labcorp from accepting self-ordered draws. | - [What a high RDW means (causes, symptoms, next steps)](https://www.test-well.com/biomarkers/rdw/high) ## Common questions about RDW ### Do I need a doctor's order to test my rdw? 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 RDW results? Most RDW 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 RDW test cost? Our CBC with Differential starts at $21.99. 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 RDW test? Fasting is not required for the RDW test. You can have your blood drawn any time of day. ### Which lab will process my RDW 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 - [AACC Lab Tests Online](https://www.testing.com/tests/red-blood-cell-indices/) - [MedlinePlus (NIH) — RDW (Red Cell Distribution Width)](https://medlineplus.gov/lab-tests/rdw-red-cell-distribution-width/) ## Related biomarkers - [Hemoglobin](https://www.test-well.com/biomarkers/hemoglobin) - [Hematocrit](https://www.test-well.com/biomarkers/hematocrit) - [White Blood Cell Count](https://www.test-well.com/biomarkers/white-blood-cell-count) - [Platelet Count](https://www.test-well.com/biomarkers/platelet-count) - [Red Blood Cell Count](https://www.test-well.com/biomarkers/red-blood-cell-count) - [MCV](https://www.test-well.com/biomarkers/mcv) - [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/rdw 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.