Later today means at some point after now but before the speaker's current day ends. By tomorrow means no later than some point associated with tomorrow—but that point may be the start of the day, a work deadline during it, or the end of it. Neither phrase is precise enough for every workplace dependency.
“I’ll send an update later today.”
“Can you finish this by tomorrow?”
Both identify a general time window. Neither provides a clock time or time zone.
What does later today imply?
Later establishes an event after the present moment. Today keeps it within the current local calendar day.
In ordinary workplace use, later today often means during the speaker's remaining working hours, not at 11:59 p.m. A colleague might send the update after lunch, after a meeting, or before logging off.
The phrase can be an intention rather than a guaranteed deadline:
“I hope to look at it later today.”
Hope to adds uncertainty. Compare the firmer:
“I will send it by 4:00 p.m. today.”
The second sentence commits to a latest time, provided the zone is shared or stated.
What does by tomorrow imply?
The preposition by marks a latest point: at or before a specified time. The problem is that tomorrow names a whole day rather than one point within it.
Some listeners interpret by tomorrow as before tomorrow begins. Others understand it as sometime during tomorrow, often by the end of the workday. Context may help, but the phrase can still create opposing expectations.
Compare:
“Please send it by 9:00 a.m. tomorrow.”
“Please send it by the end of your workday tomorrow.”
“Please send it before tomorrow's 2:00 p.m. review.”
Each one defines the operational need more clearly.
What might you hear at work?
“I’ll get back to you later today.”
The speaker intends a same-day response but may not have promised a particular hour. For the social force of that phrase, see whether “I’ll get back to you” is a promise or polite delay.
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Start a session →“We need approval by tomorrow.”
Ask when approval must arrive to protect the next step.
“Can we discuss this later?”
Unlike later today, plain later may refer to another day. It needs more scheduling information.
“I’ll do it tomorrow.”
This says when the action occurs, not necessarily when the finished result will be delivered.
What can you say naturally?
To clarify:
“What time tomorrow does the next step depend on?”
“Does later today mean before you sign off?”
To commit:
“I’ll send the update by 3:00 p.m. Eastern time today.”
To give an honest estimate:
“I expect to have an answer tomorrow afternoon. I’ll confirm the time after the technical review.”
To state the dependency:
“We need approval by 11:00 a.m. tomorrow so production can begin at noon.”
Use the real operational times in actual messages; examples should not become invented deadlines.
Today and tomorrow depend on location
At the same instant, it may be Tuesday in California and Wednesday in Japan. “Later today” sent across those locations can be logically confusing: whose today?
Prefer a spelled-out date:
“I’ll respond Wednesday, October 7, by 4:00 p.m. Pacific time.”
If you use today, add the sender's zone when the audience is distributed. In asynchronous tools, remember that the reader may open the message hours later, after “today” has changed.
Numeric dates can also vary by convention. Spell the month or use the organization's agreed format.
Midnight and end-of-day problems
By midnight tomorrow may mean the instant tomorrow begins or the instant tomorrow ends. Say 11:59 p.m. on [date] or, preferably, choose a normal working-hour cutoff when feasible.
By EOD tomorrow adds workplace context but still leaves the zone and exact end time unclear. See EOD versus COB.
Deadlines outside normal working hours can pressure people to work late. A manager should distinguish an actual business dependency from a preference and confirm feasibility.
Recognition versus production
When you hear later today, expect the same local day but ask for a time if you depend on the result. When you hear by tomorrow, recognize that by creates a latest point while tomorrow fails to identify which point.
When you write, choose among three levels:
- casual: “I’ll look later today” when no one depends on the timing;
- operational: “I’ll update you by 4:00 p.m. today”;
- international: “I’ll update you by 4:00 p.m. Eastern time on October 7.”
For early-day priority language, see what “first thing” means at work. For ambiguous weekday references, see which Friday “next Friday” means.
The practical takeaway
“Later today” is a same-day intention; “by tomorrow” sets an unclear latest point associated with the next day. When work depends on the answer, confirm the date, clock time, time zone, and the event the deadline protects.