20 × 25 × 5 is not one unique filter.

Different filter systems can share the same nominal size but use different replacement parts. Enter the number on the current filter or the model on the filter cabinet so we do not guess.

Next step

What model is printed on the filter cabinet or media air cleaner?

Use the label on the filter cabinet or media air cleaner, not the furnace model unless that is the only label available.

Use a different detail instead

Choose the detail you can identify confidently. FilterFound will keep what you already told us.

Not sure where to look? See exactly what to copy

Use the label you can reach safely. Start with the filter already in place, if you can reach it through a normal filter slot or return grille. You may also find a separate filter cabinet near the equipment. Copy exactly what is printed; FilterFound will say when another detail is needed.

Best starting point

Current filter

Read the frame of the filter already installed. Keep every letter, number, dash, and suffix.

Copy: full part or model number

Strong alternative

Filter cabinet or media air cleaner

Look on the outside of the housing around the filter slot or door. This label is often different from the furnace label.

Copy: cabinet or air-cleaner model

If that is all you can find

Furnace or air handler

Use the model from the equipment exterior. It can start the lookup, but it may not identify one installed filter by itself.

Copy: equipment model, not the serial number

Fallback

Filter size

Read the nominal size printed on the filter edge. Several different filters can share the same nominal size.

Copy: the full size, for example 20 × 25 × 5

How do I change the filter once I find the correct replacement?

Read the filter and equipment instructions. Turn the system off before opening its normal user-access filter slot or return grille.
Before removing the old filter, note or photograph the full part number, size, and airflow arrow. Check the cabinet label too, if present.
Use the replacement verified for your installed filter and cabinet. Follow the manufacturer's instructions for its frame, rails, and airflow direction; do not force it into place.
Close the filter cover and restart the system only when the filter is securely installed. If the filter is not safely accessible or the instructions are unclear, consult a qualified HVAC professional.

Generic steps do not replace model-specific instructions. A matching nominal size or MERV rating alone does not prove compatibility.

Do not remove electrical or service panels to find a label. Use only the filter or exterior labels you can reach safely.