| Cover - USD ($) $ in Millions | 12 Months Ended | ||
| Apr. 30, 2023 | Aug. 23, 2023 | Oct. 31, 2021 | |
| Document Type | 10-K/A | ||
| Amendment Flag | true | ||
| Amendment Description | This Amendment No. 1 to Form 10-K (this Amendment No.1) amends the Ocean Power Technologies, Inc. (“we”, “us”, “our” or the “Company”) Annual Report on Form 10-K for the fiscal year ending April 30, 2023, as originally filed with the Securities and Exchange Commission (“SEC”) on July 28, 2023 (the “Original Filing”). We are filing this Amendment No. 1 to include the information required by Items 10 through 14 of Part III of Form 10-K. This information was previously omitted from our Original Filing in reliance on General Instruction G(3) to Form 10-K, which permits the information in the above-referenced items to be incorporated in our Form 10-K by reference to our definitive proxy statement if such statement is filed within 120 days after the end of our fiscal year ended April 30, 2023 | ||
| Document Annual Report | true | ||
| Document Transition Report | false | ||
| Document Period End Date | Apr. 30, 2023 | ||
| Document Fiscal Period Focus | FY | ||
| Document Fiscal Year Focus | 2023 | ||
| Current Fiscal Year End Date | --04-30 | ||
| Entity File Number | 001-33417 | ||
| Entity Registrant Name | Ocean Power Technologies, Inc. | ||
| Entity Central Index Key | 0001378140 | ||
| Entity Tax Identification Number | 22-2535818 | ||
| Entity Incorporation, State or Country Code | DE | ||
| Entity Address, Address Line One | 28 ENGELHARD DRIVE | ||
| Entity Address, Address Line Two | SUITE B | ||
| Entity Address, City or Town | MONROE TOWNSHIP | ||
| Entity Address, State or Province | NJ | ||
| Entity Address, Postal Zip Code | 08831 | ||
| City Area Code | (609) | ||
| Local Phone Number | 730-0400 | ||
| Entity Well-known Seasoned Issuer | No | ||
| Entity Voluntary Filers | No | ||
| Entity Current Reporting Status | Yes | ||
| Entity Interactive Data Current | Yes | ||
| Entity Filer Category | Non-accelerated Filer | ||
| Entity Small Business | true | ||
| Entity Emerging Growth Company | false | ||
| Entity Shell Company | false | ||
| Entity Public Float | $ 40.8 | ||
| Entity Common Stock, Shares Outstanding | 58,787,578 | ||
| ICFR Auditor Attestation Flag | false | ||
| Document Financial Statement Error Correction [Flag] | false | ||
| Auditor Firm ID | 274 | ||
| Auditor Name | EisnerAmper LLP | ||
| Auditor Location | Iselin, New Jersey | ||
| Common Stock, par value $0.001 | |||
| Title of 12(b) Security | Common Stock, par value $0.001 | ||
| Trading Symbol | OPTT | ||
| Security Exchange Name | NYSE | ||
| Series A Participating Preferred Stock Purchase Rights [Member] | |||
| Title of 12(b) Security | Series A Participating Preferred Stock Purchase Rights | ||
| Trading Symbol | n/a | ||
| Security Exchange Name | NYSE |
