| Cover | Jul. 18, 2022 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Amendment Flag | false |
| Document Period End Date | Jul. 18, 2022 |
| 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 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Stock, $0.001 Par Value |
| Trading Symbol | OPTT |
| Security Exchange Name | NYSEAMER |
| Entity Emerging Growth Company | false |
