Past Tense of “input”
The past tense of input is input; the past participle is input.
Why “input” behaves this way
"Input" as a verb is a much newer creation than most entries on this site, formed in the 20th century from the existing noun "input" (itself a compound of "in" plus "put," originally an economics term for resources fed into a production process before computing adopted it). Because it was built directly on "put," which is one of English's oldest unchanging verbs, "input" inherited that same zero-change pattern by direct compounding rather than by any deep historical descent.
The word entered widespread use alongside early computing in the mid-20th century, when "to input data" became standard technical vocabulary for entering information into a machine, and the verb form spread from specialist computing jargon into general office and everyday vocabulary as computers became common household and workplace tools through the 1980s and 90s. Its sibling term "output" followed the identical path at roughly the same time, entering ordinary vocabulary directly from the same early computing context.
The common confusion
The genuine live debate is between "input" and the regularized "inputted" as the past tense — style guides and dictionaries are split, with "input" (unchanged) treated as more traditional and closer to the parent verb "put," while "inputted" has become common enough in technical and everyday writing that many editors now accept it without flagging it as an error. Corpus studies of published writing show "inputted" steadily gaining ground over the past few decades, suggesting the word may be drifting away from its parent verb's irregular behavior over time rather than staying anchored to it indefinitely. This kind of gradual regularization is actually the far more typical fate for English verbs over long stretches of time, so "input" may simply be catching up with the broader historical trend.
How it's actually used
"Input" the verb is used almost exclusively in technical, data, and workplace contexts ("input your password," "the data was input correctly"), rarely appearing in general narrative prose, which keeps it feeling like specialized vocabulary even decades after entering the dictionary as a standard verb. The noun "input" has also broadened well beyond computing to mean any contribution of ideas or opinions ("we'd love your input on this decision"), a figurative use that has arguably overtaken the literal, computing-rooted verb in sheer everyday frequency.
Across the tense system
Whichever past form a writer chooses, "input" and "inputted" both cover the simple past and the past participle equally well, with no meaningful distinction in meaning between the two competing forms — the choice is purely a matter of house style or personal habit, not grammar. Some technical manuals even alternate between the two across different sections written by different authors, a genuine inconsistency that most readers barely register given how close the two variants sound and look.
Common real mistakes
The most common inconsistency isn't a wrong form so much as switching between "input" and "inputted" within the same document, which many style guides flag purely for consistency's sake rather than correctness. A separate, unrelated error is confusing the verb "input" with the near-synonym "enter," which behaves as a fully regular verb ("entered") and doesn't carry the same debate. Technical documentation teams often settle this by house style rather than by appeal to any outside authority, since major dictionaries genuinely list both forms as acceptable without preference.
Examples
- She input the figures directly into the spreadsheet.
- He has input the same data twice by mistake.
- They input their answers before the timer ran out.
- The technician inputted the new settings this morning.
- Please input your account number to continue.
- We had input all the survey responses by Friday.
- The system rejects any value that wasn't correctly input.
Memory trick
Remember "input" is literally "in" plus "put" glued together, so it borrows "put"'s famous refusal to change form at all. If you're unsure whether to write "input" or "inputted," either is defensible today — just pick one and stay consistent within the same piece of writing. Picture a keyboard: whatever you type "in" is what got "put" there, and neither half of that compound ever bothers changing shape.