Find a time you both have
One availability window per person. Enter each date and time in that person's own zone.
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Use 24-hour times. An end earlier than the start means the following local day. The start is included; the end is not. Equal times are not a full day. Dates may differ between people.
Date and clock-change rules
Matches actual UTC minutes against local availability, at one-minute precision, for dates from 2000 to 2099. It is not a recurring schedule. Check again for each date, especially when countries change their clocks on different weeks.
A missing start or end time during a clock change is rejected. Missing minutes inside a window count zero. Repeated clock times include both occurrences and may produce separate overlaps. Offsets distinguish them; elapsed minutes may differ from the wall-clock span. Results use your browser's time-zone database. Confirm future plans after rule changes.
Winter example: on 15 January 2026, London 19:00-23:00 and New York 18:00-22:00 only touch at an excluded endpoint. There is no call window.
Enter or edit availability, then choose Find overlap.
Use the planner on this page to compare two dated availability windows, then choose a time together. It calculates when both windows overlap, not how much either partner cares. If one window ends exactly when the other starts, the answer is zero minutes. Protect sleep, work, and the right to decline before treating any calculated slot as an agreement.
The inputs are deliberately small: a timezone, local start date, start time, and end time for each person. You do not need an account, a calendar connection, or private relationship messages. Enter the hours you are actually willing and able to use, not the whole evening you wish were free.
There may be a useful overlap, a short one, or none. Each is a valid scheduling result. A tool that quietly adds an hour after someone's stated bedtime has not found time. It has changed the agreement without asking.
The Contact-Window Calculator
The calculation compares actual instants, which matters when local clocks differ or change. You can also work a simple example by hand: convert both windows to a shared clock, take the later start and earlier end, and check that the end is later than the start. Equal endpoints give no usable duration.
One free window per person is supported in each calculation. If a day has a morning break and a separate evening opening, run separate comparisons. Do not include the working hours between them as if they were free. A longer input is not more accurate merely because it produces an answer you prefer.
Enter the date, not just the city
Choose timezone names such as Europe/London and America/New_York. The suggestions are starting points; another valid IANA zone can be entered. Avoid ambiguous abbreviations such as EST. A city's offset can vary by date, while a fixed offset may miss those changes.
The IANA Time Zone Database records local time rules and is updated for changes to offsets, boundaries, and daylight-saving policy. The planner uses your browser's timezone data. Keep your software current and confirm future plans after rule changes rather than assuming a result is a permanent promise.
Use each person's own local start date. For a late-night call across a large offset, those dates can be different. A Monday where you are does not necessarily mean Monday where your partner is. Read the date as well as the hour in the result before suggesting a call.
The planner accepts dates from 2000 to 2099 and works at one-minute precision. That is the tool's calculation range, not a forecast that civil-time rules will remain unchanged. A result for a future year depends on the rules currently available to the browser.
Define availability before looking for overlap
Subtract work, sleep, commuting, care responsibilities, and time either person wants to keep uncommitted. Being awake is not the same as being available. Being off work is not consent to spend all of that time on a call.
Ask your partner for their window rather than inferring it from online status, a shared location, or when they last replied. A break at work may allow a brief message but not a private conversation. Enter it as a call window only if the person says it is usable for that purpose.
If the end time is earlier than the start time, the planner treats the end as the following local day. For example, a 22:30-01:00 window begins on the entered date and ends after midnight. Equal start and end times are not interpreted as a full day; choose a real nonzero window.
If an input is blank or invalid, correct the marked field and choose Find overlap again. Editing a value clears the previous result until you recalculate. That prevents an old answer from looking like the result of your new hours.
Winter example: an endpoint is not a call
Use 2026-01-15 for both local start dates, Europe/London for one person, and America/New_York for the other. London is on GMT, UTC+00:00; New York is on standard time, UTC-05:00. This example assumes those specific dates and rules, not a five-hour difference throughout the year.
| Person | Entered availability | On the New York clock |
|---|---|---|
| London | 19:00-23:00 | 14:00-18:00 |
| New York | 18:00-22:00 | 18:00-22:00 |
There are zero minutes of overlap. At 18:00 in New York, the London window has ended. You cannot fit a short call into a boundary with no duration, and you cannot extend the London window to midnight without changing the input and getting agreement.
The Load winter example button supplies this no-overlap case. Choose Find overlap to see the result. It is included to make the boundary visible, not to suggest that these are the hours a couple should keep. If the result disappoints you, change the plan together rather than reinterpreting the arithmetic.
A genuinely available hour and a matching message
For a separate illustrative example, keep London at 19:00-23:00 on 2026-01-15, but suppose the New York person confirms they are available from 17:00-22:00 that day. This is a new availability assumption, not time discovered in the previous example.
Now the shared window is 17:00-18:00 in New York and 22:00-23:00 in London, lasting 60 minutes. A proposed call from 17:15 to 17:45 in New York is therefore 22:15 to 22:45 in London. It stays inside both windows and leaves time before each boundary.
FOR THAT REVISED EXAMPLE, YOU COULD ASK
On 15 January, would 17:15-17:45 New York time, 22:15-22:45 London time, work for a call? If that feels too late, let's pick another day or exchange a voice note instead.
The message offers a time, duration, date, and alternative. It does not turn the available hour into a daily obligation. If either person says no, the next step is another proposal, not a conclusion about their affection. A window is an option until both people agree to it.
Recalculate around daylight-saving changes
According to GOV.UK's clock-change dates, UK clocks change on 29 March and 25 October in 2026. NIST's US daylight-saving rules give 8 March and 1 November for US locations that observe the change. New York and London therefore do not keep the same difference during every week of the year.
That is why the planner asks for dates and not just cities. A recurring Thursday call can move on one person's clock before it moves on the other's. Recheck the specific date around transitions, and decide which local time should remain fixed. Do not silently make the other person responsible for noticing the change.
Clock changes can also create a local time that never occurs, or one that occurs twice. The planner rejects a missing start or end time. Missing minutes inside a window add no elapsed time. Repeated clock times include both occurrences and can produce separate overlapping intervals, with offsets shown to distinguish them.
Read those intervals carefully. A wall-clock span is not always the same as elapsed duration. If an answer is ambiguous for your plans, choose a time outside the transition or confirm the exact offset and date together. The tool does not create or synchronize calendar invitations for you.
No overlap is a scheduling result, not a verdict
When there is no overlap, discuss a different day, a genuinely available break, or an asynchronous exchange. Agree on what a response expectation means for both people. A voice note sent while someone sleeps need not demand an immediate reply.
Do not assume weekends are free or that rotating late nights makes sleep loss harmless. Each person can protect rest and decline a slot. If every proposed live window is unworkable, the useful conversation is about what arrangement is sustainable, not how to make the calculator display a positive number.
The guide to no overlap in long-distance work schedules explores that conversation. For an agreed window, planning virtual dates across time zones and discussing call frequency offer further prompts. None supplies a universal minimum number of minutes a couple must spend together.
Private inputs and the limits of the result
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The calculator cannot verify the availability entered, assess a relationship, or know why a call was missed. Use the tools hub for other planning aids, and dating across time zones for work for context. The result is a possible time to discuss, not evidence that either person owes it to the other.