Advanced gold explorer Alto Metals is already plotting its next resource update after its March upgrade nearly doubled its gold inventory.

The company's Sandstone Gold Project in Western Australia now has an indicated and inferred resource of 12.4 million tonnes at 1.6 grams per tonne gold for 635,000 ounces, using a 0.5gpt cut-off and constrained within a A$2500 an ounce pit shell.

The upgrade was the result of 60,000m of drilling in 2021.

The resource is shallow with more than 90% sitting within 160m of surface.

Alto estimates the discovery cost equates to less than $14/oz of gold.

The resource estimate was independently prepared by leading consultants Snowden Optiro.

The estimate incorporates the Lord Nelson, Lord Henry, Havilah Camp and Vanguard Camp, which all remain open along strike and at depth.

Importantly, the latest figure excluded an update for the 74,000oz Indomitable Camp, where Alto reported strong results in February.

Results from Indomitable included 21m at 2gpt gold from 46m, including 1m at 14.9gpt gold and 1m at 6.3gpt gold and 15m at 2.2gpt gold from 44m, including 2m at 13.2gpt gold.

Alto managing director Matthew Bowles said the latest estimate was very much an interim upgrade, with significant scope to add additional shallow, high-grade ounces.

"The company remains focused on adding further ounces with extensional drilling and plans to mobilise additional rigs to fast-track this resource growth and also test a number of our high-priority regional targets," he said.

Alto's 2022 exploration campaign kicked off in early March.

The company plans to continually drill all year, with up to 60,000m budgeted.

An initial 18,000m reverse circulation program is underway, targeting resource growth and high-grade depth extensions at Lord Nelson, Indomitable and Vanguard.

At least one RC rig has been secured for the rest of 2022, but Alto will seek to secure further rigs to accelerate exploration and resource growth.

The company is planning to update the resource again in the second half of the year, which should include an update to the Indomitable resource.

Preliminary metallurgical test work indicated gold recoveries averaging 96% in Lord Nelson primary zone mineralisation and over 93% in oxide and transitional zones.

Test work on samples from the Vanguard Camp, Indomitable Camp, Havilah and Ladybird deposits returned an average recovery of more than 92%.

The work will be built on as part of early study work.

Alto remains well-funded with cash of $6.1 million at the start of the year after a $7 million capital raising in late 2021.

With the speed at which Alto is adding ounces and the scale of the +900sq.km Sandstone Gold Project, it is clear to see why the company is confident in its strategy of progressing towards developing a stand-alone gold operation.