Calculator Inputs
Use test dates if available; add exposure range for planning.
Example Data Table
These examples show how the calculator summarizes windows and intervals.
| Scenario | Exposure | Last Negative | First Positive | Marker | Expected Range (days) | Estimated Window | Point Estimate |
|---|---|---|---|---|---|---|---|
| A | 2026-01-02 | 2026-01-10 | 2026-01-18 | Total | 7–30 | 2026-01-10 → 2026-01-18 | 2026-01-14 |
| B | 2026-02-01 | — | — | IgG | 10–35 | 2026-02-11 → 2026-03-08 | 2026-02-22 |
| C | 2026-01-05 | 2026-01-20 | 2026-02-10 | IgM | 7–21 | Overlap may be narrow or absent | Review inputs |
Formula Used
- WindowStart = LastNegativeDate
- WindowEnd = FirstPositiveDate
- PointEstimate = midpoint(WindowStart, WindowEnd)
- WindowStart = ExposureDate + LowDays
- WindowEnd = ExposureDate + HighDays
- PointEstimate = ExposureDate + MedianDays
- HybridStart = max(TestStart, ExposureStart)
- HybridEnd = min(TestEnd, ExposureEnd)
- AdjDays = round((1 - Sensitivity/100) × MaxLagDays)
- AdjustedStart = WindowStart - AdjDays
- AdjustedEnd = WindowEnd + AdjDays
How to Use This Calculator
- Choose a condition preset and antibody marker, then review the expected day range.
- Enter the last negative and first positive test dates when you have them.
- If you know the exposure date, keep the expected day range enabled.
- Set assay sensitivity and max lag to widen the adjusted window if needed.
- Click Calculate to see results above the form, below the header.
- Use CSV or PDF downloads to share results with your team.
For clinical decisions, confirm with appropriate testing guidelines and professional advice.
Seroconversion timing and immune markers
Seroconversion is the point when antibodies become detectable after exposure. Early responses are often reflected by IgM, followed by IgG and broader total‑antibody signals. Because assays, pathogens, and hosts vary, timing is best expressed as a window rather than a single date. Real‑world windows can span multiple weeks, depending on immune status and assay cutoff.
Date inputs captured by this calculator
Two evidence streams can be entered. The test‑window method uses the last documented negative result and the first documented positive result to bound when seroconversion likely occurred. The exposure‑based method uses an estimated exposure date plus an expected low, median, and high range in days. When both are provided, the hybrid overlap highlights where the two streams agree. If dates are entered out of order, the calculator normalizes the window.
Calculated window, midpoint, and day offsets
The calculator outputs a raw start and end date, plus a point estimate based on the midpoint of the selected window. It also reports the number of days from exposure and symptom onset to the point estimate when those dates are supplied. These offsets help compare cohorts, align sample collection times, and standardize reporting across repeat visits. For research logs, midpoint reporting supports consistent aggregation without hiding the underlying bounds.
Sensitivity adjustment and confidence flag
To reflect imperfect detection, the adjusted window widens the raw interval by an amount derived from sensitivity and a user‑set maximum lag. Lower sensitivity increases the widening, acknowledging that a true positive may appear later than expected. Confidence is summarized using the gap between tests: tighter gaps generally yield higher confidence, while wide gaps broaden uncertainty. Treat the label as a summary, not a guarantee of accuracy.
Practical reporting and audit trail
For sharing and record keeping, results can be exported as CSV or PDF. The included example table shows how scenarios are summarized with dates, marker choice, ranges, and estimates. Use the outputs to plan retesting, document study timelines, and communicate uncertainty clearly. Always interpret results alongside clinical context and laboratory guidance. When in doubt, repeat testing at an appropriate interval and record assay type for comparability.
FAQs
1) What does seroconversion mean?
It means antibodies have risen above an assay’s detection threshold after exposure or infection, turning a previously negative serology result into a positive one.
2) What if I do not know the exposure date?
Use the test‑window method by entering your last negative and first positive test dates. The calculator will bound the likely interval and provide a midpoint estimate.
3) Why does sensitivity change the adjusted window?
Lower sensitivity increases the chance of delayed detection. The tool widens the interval by a small, capped number of days to reflect that uncertainty.
4) How is the confidence label determined?
It summarizes how tight the evidence is, mainly from the gap between the last negative and first positive tests, then modestly downgraded when sensitivity is low.
5) Can I use this for vaccination antibody responses?
Yes, for planning and documentation. Enter the vaccination date as the exposure date and tune the expected day range to match the assay and protocol you are using.
6) Does this calculator replace medical advice?
No. It provides an estimated timing window for discussion and follow‑up planning. Interpretation should follow clinical evaluation, test limitations, and local guidelines.